G\u00e9latine-Diazo : L’Alchimie Pictorialiste<\/title>\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=DM+Sans:wght@400;500;600&family=EB+Garamond:ital,wght@0,400;0,600;1,400&display=swap\" rel=\"stylesheet\">\n<style>\n:root {\n --c-bg: #ffffff;\n --c-surface: #ffffff;\n --c-border: #e2ddd6;\n --c-border-md: #cec8be;\n --c-text: #1a1714;\n --c-muted: #6b6560;\n --c-faint: #9c958d;\n --c-accent: #2c4a3e;\n --c-accent-lt: #e8f0eb;\n --c-warm: #f5f0e8;\n --c-amber: #7a4e0a;\n --c-amber-lt: #fdf0d5;\n --font-body: 'EB Garamond', Georgia, serif;\n --font-ui: 'DM Sans', system-ui, sans-serif;\n --r: 10px;\n}\n*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }\n\n\/* \u2500\u2500 Wrapper \u2500\u2500 *\/\n.gd {\n background: var(--c-bg);\n border: 1px solid var(--c-border);\n border-radius: var(--r);\n padding: 24px 18px 28px;\n font-family: var(--font-ui);\n color: var(--c-text);\n max-width: 100%;\n}\n\n\/* \u2500\u2500 Hero header \u2500\u2500 *\/\n.gd-hero {\n background: var(--c-accent);\n border-radius: 8px;\n padding: 22px 20px 20px;\n margin-bottom: 24px;\n position: relative;\n overflow: hidden;\n}\n.gd-hero::before {\n content: '';\n position: absolute;\n top: -30px; 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}\n.stxt em { color: var(--c-muted); font-style: italic; font-size: 12px; }\n\n\/* \u2500\u2500 Recette \/ dosage \u2500\u2500 *\/\n.recette {\n background: var(--c-surface);\n border: 1px solid var(--c-border);\n border-radius: 8px;\n overflow: hidden;\n margin-bottom: 14px;\n}\n.recette-head {\n background: #f2ede6;\n padding: 8px 14px;\n font-size: 10px; font-weight: 600;\n letter-spacing: .07em; text-transform: uppercase;\n color: var(--c-muted);\n border-bottom: 1px solid var(--c-border-md);\n}\n.recette-row {\n display: flex; align-items: flex-start;\n gap: 10px; padding: 10px 14px;\n border-bottom: 1px solid var(--c-border);\n}\n.recette-row:last-child { border-bottom: none; }\n.r-qty {\n font-family: monospace; font-size: 13px;\n font-weight: 600; color: var(--c-accent);\n min-width: 60px; flex-shrink: 0; padding-top: 1px;\n}\n.r-desc { font-size: 13px; color: var(--c-text); line-height: 1.5; }\n.r-desc em { color: var(--c-muted); font-size: 12px; font-style: italic; }\n\n\/* \u2500\u2500 Pigment selector (visual) \u2500\u2500 *\/\n.pigments { display: flex; flex-direction: column; gap: 8px; margin-bottom: 14px; }\n.pig-row {\n display: flex; align-items: center; gap: 12px;\n padding: 10px 12px;\n border: 1px solid var(--c-border);\n border-radius: 8px; background: var(--c-bg);\n}\n.pig-dot {\n width: 32px; height: 32px; border-radius: 50%;\n flex-shrink: 0;\n border: 1px solid rgba(0,0,0,.12);\n}\n.pig-name { font-weight: 600; font-size: 13.5px; color: var(--c-accent); }\n.pig-effect { font-size: 12px; color: var(--c-muted); margin-top: 2px; }\n.pig-badge {\n margin-left: auto; flex-shrink: 0;\n font-size: 10px; font-weight: 600;\n padding: 2px 8px; border-radius: 20px;\n background: var(--c-accent-lt); color: var(--c-accent);\n}\n\n\/* \u2500\u2500 Temps expo visuel \u2500\u2500 *\/\n.expo-bars { display: flex; flex-direction: column; gap: 8px; margin-bottom: 14px; }\n.expo-row { display: flex; align-items: center; gap: 10px; }\n.expo-lbl { font-size: 12px; color: var(--c-muted); width: 130px; flex-shrink: 0; }\n.expo-bar-wrap { flex: 1; height: 14px; background: #ede8e0; border-radius: 7px; overflow: hidden; }\n.expo-bar { height: 100%; border-radius: 7px; background: var(--c-accent); }\n.expo-val { font-size: 11px; font-weight: 600; color: var(--c-text); width: 55px; text-align: right; flex-shrink: 0; }\n\n\/* \u2500\u2500 Checklist vrai\/faux \u2500\u2500 *\/\n.checks { display: flex; flex-direction: column; gap: 7px; margin-bottom: 14px; }\n.chk {\n display: flex; align-items: flex-start; gap: 9px;\n padding: 9px 11px;\n border: 1px solid var(--c-border);\n border-radius: 7px; background: var(--c-bg);\n}\n.cico {\n width: 20px; height: 20px; border-radius: 50%;\n flex-shrink: 0; margin-top: 1px;\n display: flex; align-items: center; justify-content: center;\n}\n.cico.ok { background: #d4e8d8; }\n.cico.ko { background: #f0d8d8; }\n.cico svg { width: 10px; height: 10px; stroke-width: 2.5; stroke-linecap: round; stroke-linejoin: round; fill: none; }\n.cico.ok svg { stroke: #2a6a3a; }\n.cico.ko svg { stroke: #8a2a2a; }\n.chk-txt { font-size: 13.5px; color: var(--c-text); line-height: 1.55; }\n.chk-txt em { color: var(--c-muted); font-style: italic; font-size: 12px; }\n\n\/* \u2500\u2500 Couches superpos\u00e9es (sch\u00e9ma) \u2500\u2500 *\/\n.layers-schema {\n background: var(--c-surface);\n border: 1px solid var(--c-border);\n border-radius: 8px; overflow: hidden;\n margin-bottom: 14px;\n}\n.layer-row {\n display: flex; align-items: center; gap: 12px;\n padding: 10px 14px;\n border-bottom: 1px solid var(--c-border);\n}\n.layer-row:last-child { border-bottom: none; }\n.layer-color {\n width: 36px; height: 18px; border-radius: 4px;\n flex-shrink: 0; border: 1px solid rgba(0,0,0,.1);\n}\n.layer-num {\n width: 22px; height: 22px; border-radius: 50%;\n font-size: 11px; font-weight: 600; color: #fff;\n display: flex; align-items: center; justify-content: center;\n flex-shrink: 0;\n}\n.layer-title { font-weight: 600; font-size: 13px; color: var(--c-accent); }\n.layer-detail { font-size: 12px; color: var(--c-muted); margin-top: 2px; }\n\n\/* \u2500\u2500 S\u00e9parateur interne \u2500\u2500 *\/\n.inner-sep { border-top: 1px solid var(--c-border); margin: 14px 0; }\n\n\/* \u2500\u2500 Footer \u2500\u2500 *\/\n.gd-footer {\n margin-top: 20px; padding-top: 16px;\n border-top: 1px solid var(--c-border);\n display: flex; flex-wrap: wrap; gap: 10px;\n align-items: center;\n}\n.foot-badge {\n font-size: 11px; font-weight: 500;\n padding: 4px 12px; border-radius: 20px;\n border: 1px solid var(--c-border-md);\n color: var(--c-muted);\n}\n.foot-badge.green { background: var(--c-accent-lt); color: var(--c-accent); border-color: #b8d4c0; }\n<\/style>\n<\/head>\n<body>\n\n<div class=\"gd\">\n\n \n <div class=\"gd-hero\">\n <div class=\"gd-hero-kicker\">Proc\u00e9d\u00e9s alternatifs \u2014 Pictorialisme<\/div>\n <h1>L’Alchimie Pictorialiste :<br>G\u00e9latine-Diazo (DAS)<\/h1>\n <div class=\"gd-hero-sub\">Recr\u00e9er la profondeur mystique des tirages de Steichen \u2014 sans bichromate<\/div>\n <div class=\"gd-hero-tags\">\n <span class=\"hero-tag\">Multicouche<\/span>\n <span class=\"hero-tag\">Contact UV<\/span>\n <span class=\"hero-tag\">Non toxique<\/span>\n <span class=\"hero-tag\">Niveau interm\u00e9diaire<\/span>\n <\/div>\n <\/div>\n\n \n <div class=\"steichen-box\">\n <strong>Contexte historique :<\/strong> En 2007, l’analyse scientifique du chef-d’\u0153uvre de Steichen <em>Midnight \u2013 Lake George<\/em> \u2014 longtemps cru \u00eatre un simple tirage au platine \u2014 r\u00e9v\u00e8le un secret : une <strong>superposition de cyanotype et de gomme bichromat\u00e9e<\/strong>. Ce bloc vous guide pour recr\u00e9er cette profondeur en rempla\u00e7ant le bichromate toxique par le <strong>DAS (Diazidostilbene)<\/strong>, plus s\u00fbr et plus stable.\n <\/div>\n\n<div style=\"margin: 14px 0; border-radius: 8px; overflow: hidden; border: 1px solid #e2ddd6;\">\n <img decoding=\"async\"\n src=\"https:\/\/nicolaslouis.com\/wordpress\/wp-content\/uploads\/2026\/03\/Edward_Steichen-_Road_into_the_Valley_-_Moonrise.webp\"\n alt=\"Autochrome Lumi\u00e8re \u2014 description de l'image\"\n style=\"width: 100%; height: auto; display: block;\"\n \/>\n <div style=\"padding: 8px 14px; font-size: 12px; color: #9c958d; font-style: italic; background: #f5f0e8;\">\n Edward Steichen Road into the Valley Moonrise\n <\/div>\n<\/div>\n \n <div class=\"sections\">\n\n \n <div class=\"sec open\" id=\"s0\">\n <button class=\"sec-trigger\" onclick=\"toggle('s0')\">\n <span class=\"sec-num\">1<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">Le mat\u00e9riel n\u00e9cessaire<\/span>\n <span class=\"sec-sub\">Chimie, liants, pigments & outillage<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">La g\u00e9latine-diazo repose sur trois composants principaux : le liant (g\u00e9latine), le sensibilisateur (DAS) et le pigment (aquarelle). Ces produits sont disponibles chez des fournisseurs sp\u00e9cialis\u00e9s comme Disactis ou Labo Argentique.<\/p>\n\n <div class=\"slabel\">Chimie et liants<\/div>\n <div class=\"params\">\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M9 3H5a2 2 0 0 0-2 2v4m6-6h10a2 2 0 0 1 2 2v4M9 3v18m0 0h10a2 2 0 0 0 2-2V9M9 21H5a2 2 0 0 1-2-2V9m0 0h18\"\/><\/svg><\/div>\n <div><div class=\"pkey\">G\u00e9latine<\/div><div class=\"pval\">Photographique 250 Bloom ou alimentaire neutre <em>\u2014 en feuilles (2 g\/feuille) ou en poudre<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M19.428 15.428a2 2 0 00-1.022-.547l-2.387-.477a6 6 0 00-3.86.517l-.318.158a6 6 0 01-3.86.517L6.05 15.21a2 2 0 00-1.806.547M8 4h8l-1 1v5.172a2 2 0 00.586 1.414l5 5c1.26 1.26.367 3.414-1.415 3.414H4.828c-1.782 0-2.674-2.154-1.414-3.414l5-5A2 2 0 009 10.172V5L8 4z\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Sensibilisateur DAS<\/div><div class=\"pval\">Diazidostilbene en poudre <em>\u2014 diluer \u00e0 10% dans de l’eau distill\u00e9e avant usage<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><circle cx=\"12\" cy=\"12\" r=\"5\"\/><path d=\"M12 1v4M12 19v4M4.22 4.22l2.83 2.83M16.95 16.95l2.83 2.83M1 12h4M19 12h4M4.22 19.78l2.83-2.83M16.95 7.05l2.83-2.83\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Pigments<\/div><div class=\"pval\">Aquarelles haute qualit\u00e9 en tube <em>\u2014 Noir de fum\u00e9e, Bleu de Prusse, Terre d’Ombre<\/em><\/div><\/div>\n <\/div>\n <\/div>\n\n <div class=\"slabel\">Pourquoi l’aquarelle en tube ?<\/div>\n <div class=\"tip\"><strong>Pigments broy\u00e9s fins :<\/strong> l’aquarelle contient des pigments extr\u00eamement fins d\u00e9j\u00e0 m\u00e9lang\u00e9s \u00e0 de la gomme arabique. Cela permet une dissolution parfaite dans la g\u00e9latine chaude, sans grains ni grumeaux qui g\u00e2cheraient la nettet\u00e9 de l’image. Les gouaches ou peintures acryliques sont \u00e0 \u00e9viter.<\/div>\n\n <div class=\"slabel\">Choix du pigment \u2014 teinte & atmosph\u00e8re<\/div>\n <div class=\"pigments\">\n <div class=\"pig-row\">\n <span class=\"pig-dot\" style=\"background:#2a2a2a\"><\/span>\n <div><div class=\"pig-name\">Noir de fum\u00e9e<\/div><div class=\"pig-effect\">Rendu neutre et velout\u00e9 \u2014 profondeur maximale<\/div><\/div>\n <span class=\"pig-badge\">Ombres<\/span>\n <\/div>\n <div class=\"pig-row\">\n <span class=\"pig-dot\" style=\"background:#1a3a6a\"><\/span>\n <div><div class=\"pig-name\">Bleu de Prusse \/ Outremer<\/div><div class=\"pig-effect\">Atmosph\u00e8re nocturne froide \u2014 esprit pictorialiste<\/div><\/div>\n <span class=\"pig-badge\">Ambiance<\/span>\n <\/div>\n <div class=\"pig-row\">\n <span class=\"pig-dot\" style=\"background:#6b4a2a\"><\/span>\n <div><div class=\"pig-name\">Terre d’Ombre<\/div><div class=\"pig-effect\">Aspect s\u00e9pia \/ ancien \u2014 proche du tirage platine chaud<\/div><\/div>\n <span class=\"pig-badge\">Vintage<\/span>\n <\/div>\n <\/div>\n\n <div class=\"tip\"><strong>Le m\u00e9lange Steichen :<\/strong> ne mettez pas 2 g de noir pur. Essayez <strong>1,5 g de Noir de fum\u00e9e + 0,5 g de Bleu de Prusse<\/strong>. C’est ce m\u00e9lange qui donne cette profondeur \u00ab\u00a0nuit profonde\u00a0\u00bb si caract\u00e9ristique de Midnight \u2013 Lake George.<\/div>\n\n <div class=\"inner-sep\"><\/div>\n <div class=\"slabel\">Support et outillage<\/div>\n <div class=\"params\">\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><rect x=\"3\" y=\"3\" width=\"18\" height=\"18\" rx=\"2\"\/><path d=\"M3 9h18M3 15h18\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Papier aquarelle<\/div><div class=\"pval\">300 g\/m\u00b2 minimum <em>\u2014 Arches, Fabriano ou Saunders Waterford<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M3 3l7 7M10 10l4 4M14 14l7 7\"\/><path d=\"M5 5a10 10 0 0 1 14 14\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Application<\/div><div class=\"pval\">Pinceau large Spalter ou tige en verre (Puddle Pusher) <em>\u2014 \u00e9viter les pinceaux synth\u00e9tiques fins<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><circle cx=\"12\" cy=\"12\" r=\"9\"\/><path d=\"M12 7v5l3 3\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Source UV<\/div><div class=\"pval\">Insoleuse \u00e0 tubes actiniques ou LED UV <em>\u2014 ou soleil direct (moins reproductible)<\/em><\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s1\">\n <button class=\"sec-trigger\" onclick=\"toggle('s1')\">\n <span class=\"sec-num\">2<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">La recette de la solution sensible<\/span>\n <span class=\"sec-sub\">Dosages pr\u00e9cis pour 100 ml de solution<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">La pr\u00e9cision du dosage est d\u00e9terminante. Pr\u00e9parez toujours votre solution sous lumi\u00e8re att\u00e9nu\u00e9e (lumi\u00e8re tungst\u00e8ne ou ambre) \u2014 le DAS est sensible aux UV d\u00e8s sa dissolution.<\/p>\n\n <div class=\"slabel\">\u00c9tape A \u2014 Pr\u00e9parer la g\u00e9latine (10%)<\/div>\n <div class=\"recette\">\n <div class=\"recette-head\">Base : 100 ml de solution<\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">90 ml<\/div><div class=\"r-desc\">Eau distill\u00e9e froide <em>\u2014 verser en premier dans le r\u00e9cipient<\/em><\/div><\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">10 g<\/div><div class=\"r-desc\">G\u00e9latine <em>\u2014 saupoudrer, laisser gonfler 20\u201330 min sans remuer<\/em><\/div><\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">40\u201345\u00b0C<\/div><div class=\"r-desc\">Bain-marie <em>\u2014 fondre doucement en remuant pour \u00e9viter les bulles<\/em><\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">\u00c9tape B \u2014 Colorer et sensibiliser<\/div>\n <div class=\"alert\"><strong>Lumi\u00e8re att\u00e9nu\u00e9e obligatoire<\/strong> \u2014 r\u00e9aliser cette \u00e9tape sous lumi\u00e8re tungst\u00e8ne ou ambre uniquement. Le DAS r\u00e9agit aux UV ambiants.<\/div>\n <div class=\"recette\">\n <div class=\"recette-head\">Ajouts \u00e0 la g\u00e9latine fondue (40\u00b0C)<\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">1 \u00e0 2 g<\/div><div class=\"r-desc\">Aquarelle en tube <em>\u2014 1g = gris subtil (premi\u00e8re couche), 2g = noir dense (ombres)<\/em><\/div><\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">10 ml<\/div><div class=\"r-desc\">Solution DAS \u00e0 10% <em>\u2014 ajouter en dernier, m\u00e9langer doucement<\/em><\/div><\/div>\n <\/div>\n\n <div class=\"tip\"><strong>Ratio pigment \/ g\u00e9latine :<\/strong> trop de pigment bloque les UV \u2014 la base ne durcit pas et l’image se d\u00e9colle au d\u00e9veloppement. Trop peu de pigment = image plate sans vigueur dans les noirs. La fen\u00eatre 1\u20132 g \/ 100 ml est votre zone de travail.<\/div>\n\n <div class=\"slabel\">Encollage pr\u00e9alable (secret des blancs purs)<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">Pr\u00e9parer une solution de <strong>g\u00e9latine pure \u00e0 3%<\/strong> (sans pigment ni DAS)<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">Appliquer sur le papier sec avant toute sensibilisation <em>\u2014 cela bouche les fibres et emp\u00eache le pigment de tacher les zones qui doivent rester blanches<\/em><\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">Laisser s\u00e9cher compl\u00e8tement avant le couchage sensible<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s2\">\n <button class=\"sec-trigger\" onclick=\"toggle('s2')\">\n <span class=\"sec-num\">3<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">Le processus de cr\u00e9ation<\/span>\n <span class=\"sec-sub\">Couchage, exposition UV, d\u00e9veloppement<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">Trois phases distinctes : le couchage (en obscurit\u00e9), l’exposition UV (avec le n\u00e9gatif contact), et le d\u00e9pouillage \u00e0 l’eau chaude qui r\u00e9v\u00e8le l’image en faisant fondre la g\u00e9latine non durcie.<\/p>\n\n <div class=\"slabel\">Couchage & s\u00e9chage<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">\u00c9talez votre m\u00e9lange g\u00e9latine + pigment + DAS sur le papier sec avec le Spalter. <strong>Travaillez rapidement<\/strong> \u2014 la g\u00e9latine fige vite.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">S\u00e9chage en <strong>obscurit\u00e9 totale<\/strong>, \u00e0 plat ou suspendu. Ne pas utiliser de s\u00e8che-cheveux (cr\u00e9e des bulles).<\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">Temps d’exposition UV \u2014 r\u00e9f\u00e9rences<\/div>\n <div class=\"expo-bars\">\n <div class=\"expo-row\">\n <div class=\"expo-lbl\">Insoleuse UV (actinique)<\/div>\n <div class=\"expo-bar-wrap\"><div class=\"expo-bar\" style=\"width:55%\"><\/div><\/div>\n <div class=\"expo-val\">8\u201315 min<\/div>\n <\/div>\n <div class=\"expo-row\">\n <div class=\"expo-lbl\">Plein soleil \u00e9t\u00e9 (11h\u201315h)<\/div>\n <div class=\"expo-bar-wrap\"><div class=\"expo-bar\" style=\"width:35%\"><\/div><\/div>\n <div class=\"expo-val\">5\u201310 min<\/div>\n <\/div>\n <div class=\"expo-row\">\n <div class=\"expo-lbl\">Soleil voil\u00e9 \/ hiver<\/div>\n <div class=\"expo-bar-wrap\"><div class=\"expo-bar\" style=\"width:90%\"><\/div><\/div>\n <div class=\"expo-val\">20\u201345 min<\/div>\n <\/div>\n <div class=\"expo-row\">\n <div class=\"expo-lbl\">Couche \u00e9paisse +30%<\/div>\n <div class=\"expo-bar-wrap\"><div class=\"expo-bar\" style=\"width:70%;background:#854f0b;opacity:.6\"><\/div><\/div>\n <div class=\"expo-val\">+30%<\/div>\n <\/div>\n <\/div>\n <div class=\"tip\"><strong>Pigment noir :<\/strong> le Noir de fum\u00e9e bloque davantage les UV que les pigments bruns ou bleus. Augmentez le temps de 20 \u00e0 30% si votre m\u00e9lange est tr\u00e8s sombre.<\/div>\n\n <div class=\"slabel\">La bande d’essai (m\u00e9thode indispensable)<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">D\u00e9coupez une bande de papier sensibilis\u00e9. Placez votre n\u00e9gatif dessus.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">Cachez 80% de la bande avec un carton opaque. Exposez <strong>4 minutes<\/strong>.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">D\u00e9calez le carton pour d\u00e9couvrir une nouvelle section. Exposez <strong>4 minutes de plus<\/strong>. R\u00e9p\u00e9tez jusqu’\u00e0 la fin.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">4<\/div><div class=\"stxt\">Apr\u00e8s d\u00e9veloppement : vous avez des zones \u00e0 4, 8, 12, 16, 20 min. La zone id\u00e9ale = hautes lumi\u00e8res d\u00e9taill\u00e9es sans bavures dans les noirs.<\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">D\u00e9pouillage (d\u00e9veloppement)<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">Immerger dans l’<strong>eau froide 2 minutes<\/strong> \u2014 \u00e9vacue le surplus de DAS non expos\u00e9.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">Passer dans une cuvette d’<strong>eau chaude 38\u201340\u00b0C, face vers le bas<\/strong> \u2014 la g\u00e9latine non durcie fond et r\u00e9v\u00e8le les hautes lumi\u00e8res.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">Rin\u00e7age final \u00e0 l’eau froide. S\u00e9chage \u00e0 plat sur une surface non absorbante.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s3\">\n <button class=\"sec-trigger\" onclick=\"toggle('s3')\">\n <span class=\"sec-num\">4<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">Obtenir le rendu Steichen<\/span>\n <span class=\"sec-sub\">Cyanotype de fond, multicouche, aspect mat<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">La profondeur l\u00e9gendaire de Midnight \u2013 Lake George vient de trois techniques superpos\u00e9es. Chacune apporte une dimension distincte : la vibration chromatique, le relief physique et la matit\u00e9 velout\u00e9e.<\/p>\n\n <div class=\"slabel\">1 \u2014 Le fond cyanotype : la vibration chromatique<\/div>\n <div class=\"tip\"><strong>Pourquoi \u00e7a fonctionne :<\/strong> le cyanotype s’impr\u00e8gne dans les <em>fibres<\/em> du papier, alors que la g\u00e9latine reste en <em>surface<\/em>. Cela cr\u00e9e une sensation de profondeur spatiale : le bleu semble venir de \u00ab\u00a0derri\u00e8re\u00a0\u00bb l’image. Dans les ombres port\u00e9es par la g\u00e9latine noire, des \u00e9clats de Bleu de Prusse apparaissent \u2014 l’atmosph\u00e8re de nuit \u00e9lectrique typique de Steichen.<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">R\u00e9alisez un tirage cyanotype classique (Citrate de fer ammoniacal + Ferricyanure de potassium) <em>\u2014 proc\u00e9d\u00e9 d\u00e9crit dans notre article sur les virages<\/em><\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\"><strong>Sous-exposez volontairement<\/strong> \u2014 on cherche une image fantomatique, tr\u00e8s claire, qui servira de guide color\u00e9<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">Rincez et laissez s\u00e9cher <strong>24h minimum<\/strong> \u2014 le bleu fonce l\u00e9g\u00e8rement en s’oxydant \u00e0 l’air<\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">2 \u2014 La multicouche : relief et densit\u00e9<\/div>\n <div class=\"layers-schema\">\n <div class=\"recette-head\">Ordre de superposition des couches<\/div>\n <div class=\"layer-row\">\n <div class=\"layer-num\" style=\"background:#1a3a6a\">C<\/div>\n <div class=\"layer-color\" style=\"background:#1d4a7a\"><\/div>\n <div>\n <div class=\"layer-title\">Fond cyanotype<\/div>\n <div class=\"layer-detail\">Dans les fibres \u2014 vibration bleue des ombres<\/div>\n <\/div>\n <\/div>\n <div class=\"layer-row\">\n <div class=\"layer-num\" style=\"background:#4a6a55\">1<\/div>\n <div class=\"layer-color\" style=\"background:#8a9a8a\"><\/div>\n <div>\n <div class=\"layer-title\">Couche 1 \u2014 D\u00e9tails (gris-bleu)<\/div>\n <div class=\"layer-detail\">0,5 g pigment \u2014 exposition longue (12 min) \u2014 hautes lumi\u00e8res et gris moyens<\/div>\n <\/div>\n <\/div>\n <div class=\"layer-row\">\n <div class=\"layer-num\" style=\"background:#2c4a3e\">2<\/div>\n <div class=\"layer-color\" style=\"background:#2a2a2a\"><\/div>\n <div>\n <div class=\"layer-title\">Couche 2 \u2014 Noirs profonds<\/div>\n <div class=\"layer-detail\">2 g Noir de fum\u00e9e \u2014 exposition courte (6 min) \u2014 ombres uniquement<\/div>\n <\/div>\n <\/div>\n <\/div>\n <div class=\"tip\"><strong>Le relief physique :<\/strong> en ajoutant de la mati\u00e8re (g\u00e9latine + pigment) uniquement dans les noirs, votre tirage aura une \u00e9paisseur physique diff\u00e9rente entre les blancs (papier nu) et les noirs (couche \u00e9paisse). C’est ce qui donne l’aspect \u00ab\u00a0objet d’art\u00a0\u00bb caract\u00e9ristique du pictorialisme.<\/div>\n\n <div class=\"slabel\">3 \u2014 Aspect mat : casser la brillance<\/div>\n <div class=\"checks\">\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\">Ajouter <strong>2 \u00e0 5% d’amidon de ma\u00efs (Ma\u00efzena)<\/strong> directement dans le m\u00e9lange liquide \u2014 cr\u00e9e des micro-rugosit\u00e9s invisibles qui diffusent la lumi\u00e8re<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\">Alternative : <strong>silice fumed<\/strong> \u2014 m\u00eame effet, r\u00e9sultat tr\u00e8s proche du tirage platine-palladium<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ko\"><svg viewBox=\"0 0 12 12\"><line x1=\"2\" y1=\"2\" x2=\"10\" y2=\"10\"\/><line x1=\"10\" y1=\"2\" x2=\"2\" y2=\"10\"\/><\/svg><\/div>\n <div class=\"chk-txt\">Vernis mat en finition \u2014 fonctionne mais le fini est moins organique et moins int\u00e9gr\u00e9 \u00e0 la fibre que l’amidon interne<\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s4\">\n <button class=\"sec-trigger\" onclick=\"toggle('s4')\">\n <span class=\"sec-num\">5<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">Le calage \u2014 rep\u00e9rage entre les couches<\/span>\n <span class=\"sec-sub\">Le d\u00e9fi technique de la multicouche<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">Le probl\u00e8me central de la multicouche : entre deux couches, le papier est mouill\u00e9 puis s\u00e9ch\u00e9, ce qui provoque retrait et d\u00e9formation. Repositionner le n\u00e9gatif exactement au m\u00eame endroit est le d\u00e9fi technique principal de la technique Steichen.<\/p>\n\n <div class=\"slabel\">Strat\u00e9gie 1 \u2014 Pr\u00e9-mouillage du papier<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">Avant de commencer quoi que ce soit, <strong>trempez le papier dans l’eau chaude 30 minutes<\/strong><\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">Laissez s\u00e9cher \u00e0 plat <em>\u2014 les fibres sont d\u00e9sormais \u00ab\u00a0stabilis\u00e9es\u00a0\u00bb : le papier ne bougera plus (ou presque) lors des prochains mouillages<\/em><\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">Strat\u00e9gie 2 \u2014 Syst\u00e8me de trous (m\u00e9thode d’atelier)<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">Fixez votre n\u00e9gatif sur le papier avec du ruban adh\u00e9sif repositionnable<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">\u00c0 l’aide d’une grosse aiguille, percez <strong>deux trous dans les marges<\/strong> (haut gauche + bas droit), traversant \u00e0 la fois le n\u00e9gatif et le papier<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">Pour chaque couche suivante : alignez les trous du n\u00e9gatif sur ceux du papier \u00e0 l’aide de <strong>deux \u00e9pingles<\/strong> \u2014 le recalage est imm\u00e9diat et pr\u00e9cis<\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">Deux approches du n\u00e9gatif<\/div>\n <div class=\"checks\">\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Approche expert \u2014 plusieurs n\u00e9gatifs :<\/strong> un n\u00e9gatif dense pour les hautes lumi\u00e8res (avec g\u00e9latine peu pigment\u00e9e) + un n\u00e9gatif contrast\u00e9 pour les ombres (g\u00e9latine tr\u00e8s pigment\u00e9e). Contr\u00f4le math\u00e9matique du contraste, sans risque de boucher les blancs.<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Approche Steichen \u2014 un seul n\u00e9gatif :<\/strong> on fait varier le <em>temps d’exposition<\/em> et la <em>charge en pigment<\/em> entre les couches. Plus simple, plus organique, couches qui se fondent naturellement.<\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s5\">\n <button class=\"sec-trigger\" onclick=\"toggle('s5')\">\n <span class=\"sec-num\">6<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">S\u00e9curit\u00e9 & environnement<\/span>\n <span class=\"sec-sub\">Avantages du DAS vs bichromate<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">L’avantage majeur du DAS est qu’il n’est pas class\u00e9 canc\u00e9rig\u00e8ne, contrairement au dichromate de potassium ou d’ammonium utilis\u00e9 dans la gomme bichromat\u00e9e historique.<\/p>\n\n <div class=\"checks\">\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Non canc\u00e9rig\u00e8ne<\/strong> \u2014 contrairement au bichromate (class\u00e9 CMR : canc\u00e9rig\u00e8ne, mutag\u00e8ne, reprotoxique)<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Plus stable<\/strong> \u2014 le DAS se conserve mieux que le bichromate en solution. Moins de d\u00e9gradation \u00e0 la lumi\u00e8re ambiante (sauf UV directs)<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Gants obligatoires<\/strong> pour \u00e9viter les taches de pigment. Manipuler la poudre DAS avec pr\u00e9caution (masque recommand\u00e9 lors de la pes\u00e9e)<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ko\"><svg viewBox=\"0 0 12 12\"><line x1=\"2\" y1=\"2\" x2=\"10\" y2=\"10\"\/><line x1=\"10\" y1=\"2\" x2=\"2\" y2=\"10\"\/><\/svg><\/div>\n <div class=\"chk-txt\">Temps d’exposition plus long qu’avec le bichromate <em>\u2014 8\u201315 min vs 3\u20135 min au bichromate : la patience est le prix de la s\u00e9curit\u00e9<\/em><\/div>\n <\/div>\n <\/div>\n\n <div class=\"tip\"><strong>\u00c9limination des bains :<\/strong> les eaux de d\u00e9veloppement (DAS dilu\u00e9 + pigment) peuvent \u00eatre \u00e9limin\u00e9es dans les eaux us\u00e9es domestiques en petites quantit\u00e9s. Pour des volumes importants, consulter votre d\u00e9chetterie locale.<\/div>\n <\/div>\n <\/div>\n\n <\/div>\n\n \n <div class=\"gd-footer\">\n <span class=\"foot-badge green\">DAS \u2014 non canc\u00e9rig\u00e8ne<\/span>\n <span class=\"foot-badge\">Proc\u00e9d\u00e9 alternatif<\/span>\n <span class=\"foot-badge\">XIXe si\u00e8cle revisit\u00e9<\/span>\n <span class=\"foot-badge\">Contact UV<\/span>\n <\/div>\n\n<\/div>\n\n<script>\nfunction toggle(id) {\n var s = document.getElementById(id);\n s.classList.toggle('open');\n}\n<\/script>\n\n<\/body>\n<\/html>\n","protected":false},"excerpt":{"rendered":"<p>G\u00e9latine-Diazo : L’Alchimie Pictorialiste Proc\u00e9d\u00e9s alternatifs \u2014 Pictorialisme L’Alchimie Pictorialiste :G\u00e9latine-Diazo (DAS) Recr\u00e9er la profondeur mystique des tirages de Steichen \u2014 sans bichromate Multicouche Contact UV Non toxique Niveau interm\u00e9diaire Contexte historique : En 2007, l’analyse scientifique du chef-d’\u0153uvre de Steichen Midnight \u2013 Lake George \u2014 longtemps cru \u00eatre un simple tirage au platine \u2014…<\/p>\n","protected":false},"author":1,"featured_media":4870,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"hide","_kad_post_layout":"normal","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"hide","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[150],"tags":[149],"class_list":["post-4865","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-procedes-photographiques-anciens","tag-gelatine-diazo"],"yoast_head":"\n<title>L'Alchimie Pictorialiste : G\u00e9latine-Diazo - NICOLAS LOUIS<\/title>\n<meta name=\"description\" content=\"D\u00e9couvrez comment recr\u00e9er la profondeur mystique des tirages de Steichen avec la G\u00e9latine-Diazo (DAS). 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Soumis \u00e0 des bains chimiques sp\u00e9cifiques, le bleu de Prusse \u2014 pigment de coordination form\u00e9 lors de l'exposition \u2014 peut \u00eatre partiellement ou totalement transform\u00e9, substituant ses ions fer par d'autres agents complexants, ou converti en compos\u00e9s enti\u00e8rement diff\u00e9rents. C'est\u2026","rel":"","context":"Dans "proc\u00e9d\u00e9s photographiques anciens"","block_context":{"text":"proc\u00e9d\u00e9s photographiques anciens","link":"https:\/\/nicolaslouis.com\/wordpress\/category\/procedes-photographiques-anciens\/"},"img":{"alt_text":"cyanotype d'anne Atkins, extrait du livre algae en 1843","src":"https:\/\/i0.wp.com\/nicolaslouis.com\/wordpress\/wp-content\/uploads\/2026\/03\/Anna_Atkins_algae_cyanotype.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/nicolaslouis.com\/wordpress\/wp-content\/uploads\/2026\/03\/Anna_Atkins_algae_cyanotype.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/nicolaslouis.com\/wordpress\/wp-content\/uploads\/2026\/03\/Anna_Atkins_algae_cyanotype.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/posts\/4865","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/comments?post=4865"}],"version-history":[{"count":6,"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/posts\/4865\/revisions"}],"predecessor-version":[{"id":4891,"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/posts\/4865\/revisions\/4891"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/media\/4870"}],"wp:attachment":[{"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/media?parent=4865"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/categories?post=4865"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nicolaslouis.com\/wordpress\/wp-json\/wp\/v2\/tags?post=4865"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

{"id":4865,"date":"2026-03-30T15:50:14","date_gmt":"2026-03-30T13:50:14","guid":{"rendered":"https:\/\/nicolaslouis.com\/wordpress\/?p=4865"},"modified":"2026-04-12T23:31:49","modified_gmt":"2026-04-12T21:31:49","slug":"alchimie-pictorialiste-gelatine-diazo","status":"publish","type":"post","link":"https:\/\/nicolaslouis.com\/wordpress\/2026\/03\/30\/alchimie-pictorialiste-gelatine-diazo\/","title":{"rendered":"L’Alchimie Pictorialiste : G\u00e9latine-Diazo"},"content":{"rendered":"\n\n\n\n\n\nG\u00e9latine-Diazo : L’Alchimie Pictorialiste<\/title>\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=DM+Sans:wght@400;500;600&family=EB+Garamond:ital,wght@0,400;0,600;1,400&display=swap\" rel=\"stylesheet\">\n<style>\n:root {\n --c-bg: #ffffff;\n --c-surface: #ffffff;\n --c-border: #e2ddd6;\n --c-border-md: #cec8be;\n --c-text: #1a1714;\n --c-muted: #6b6560;\n --c-faint: #9c958d;\n --c-accent: #2c4a3e;\n --c-accent-lt: #e8f0eb;\n --c-warm: #f5f0e8;\n --c-amber: #7a4e0a;\n --c-amber-lt: #fdf0d5;\n --font-body: 'EB Garamond', Georgia, serif;\n --font-ui: 'DM Sans', system-ui, sans-serif;\n --r: 10px;\n}\n*, *::before, *::after { box-sizing: border-box; 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}\n.layer-color {\n width: 36px; height: 18px; border-radius: 4px;\n flex-shrink: 0; border: 1px solid rgba(0,0,0,.1);\n}\n.layer-num {\n width: 22px; height: 22px; border-radius: 50%;\n font-size: 11px; font-weight: 600; color: #fff;\n display: flex; align-items: center; justify-content: center;\n flex-shrink: 0;\n}\n.layer-title { font-weight: 600; font-size: 13px; color: var(--c-accent); }\n.layer-detail { font-size: 12px; color: var(--c-muted); margin-top: 2px; }\n\n\/* \u2500\u2500 S\u00e9parateur interne \u2500\u2500 *\/\n.inner-sep { border-top: 1px solid var(--c-border); margin: 14px 0; }\n\n\/* \u2500\u2500 Footer \u2500\u2500 *\/\n.gd-footer {\n margin-top: 20px; padding-top: 16px;\n border-top: 1px solid var(--c-border);\n display: flex; flex-wrap: wrap; gap: 10px;\n align-items: center;\n}\n.foot-badge {\n font-size: 11px; font-weight: 500;\n padding: 4px 12px; border-radius: 20px;\n border: 1px solid var(--c-border-md);\n color: var(--c-muted);\n}\n.foot-badge.green { background: var(--c-accent-lt); color: var(--c-accent); border-color: #b8d4c0; }\n<\/style>\n<\/head>\n<body>\n\n<div class=\"gd\">\n\n \n <div class=\"gd-hero\">\n <div class=\"gd-hero-kicker\">Proc\u00e9d\u00e9s alternatifs \u2014 Pictorialisme<\/div>\n <h1>L’Alchimie Pictorialiste :<br>G\u00e9latine-Diazo (DAS)<\/h1>\n <div class=\"gd-hero-sub\">Recr\u00e9er la profondeur mystique des tirages de Steichen \u2014 sans bichromate<\/div>\n <div class=\"gd-hero-tags\">\n <span class=\"hero-tag\">Multicouche<\/span>\n <span class=\"hero-tag\">Contact UV<\/span>\n <span class=\"hero-tag\">Non toxique<\/span>\n <span class=\"hero-tag\">Niveau interm\u00e9diaire<\/span>\n <\/div>\n <\/div>\n\n \n <div class=\"steichen-box\">\n <strong>Contexte historique :<\/strong> En 2007, l’analyse scientifique du chef-d’\u0153uvre de Steichen <em>Midnight \u2013 Lake George<\/em> \u2014 longtemps cru \u00eatre un simple tirage au platine \u2014 r\u00e9v\u00e8le un secret : une <strong>superposition de cyanotype et de gomme bichromat\u00e9e<\/strong>. Ce bloc vous guide pour recr\u00e9er cette profondeur en rempla\u00e7ant le bichromate toxique par le <strong>DAS (Diazidostilbene)<\/strong>, plus s\u00fbr et plus stable.\n <\/div>\n\n<div style=\"margin: 14px 0; border-radius: 8px; overflow: hidden; border: 1px solid #e2ddd6;\">\n <img decoding=\"async\"\n src=\"https:\/\/nicolaslouis.com\/wordpress\/wp-content\/uploads\/2026\/03\/Edward_Steichen-_Road_into_the_Valley_-_Moonrise.webp\"\n alt=\"Autochrome Lumi\u00e8re \u2014 description de l'image\"\n style=\"width: 100%; height: auto; display: block;\"\n \/>\n <div style=\"padding: 8px 14px; font-size: 12px; color: #9c958d; font-style: italic; background: #f5f0e8;\">\n Edward Steichen Road into the Valley Moonrise\n <\/div>\n<\/div>\n \n <div class=\"sections\">\n\n \n <div class=\"sec open\" id=\"s0\">\n <button class=\"sec-trigger\" onclick=\"toggle('s0')\">\n <span class=\"sec-num\">1<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">Le mat\u00e9riel n\u00e9cessaire<\/span>\n <span class=\"sec-sub\">Chimie, liants, pigments & outillage<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">La g\u00e9latine-diazo repose sur trois composants principaux : le liant (g\u00e9latine), le sensibilisateur (DAS) et le pigment (aquarelle). Ces produits sont disponibles chez des fournisseurs sp\u00e9cialis\u00e9s comme Disactis ou Labo Argentique.<\/p>\n\n <div class=\"slabel\">Chimie et liants<\/div>\n <div class=\"params\">\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M9 3H5a2 2 0 0 0-2 2v4m6-6h10a2 2 0 0 1 2 2v4M9 3v18m0 0h10a2 2 0 0 0 2-2V9M9 21H5a2 2 0 0 1-2-2V9m0 0h18\"\/><\/svg><\/div>\n <div><div class=\"pkey\">G\u00e9latine<\/div><div class=\"pval\">Photographique 250 Bloom ou alimentaire neutre <em>\u2014 en feuilles (2 g\/feuille) ou en poudre<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M19.428 15.428a2 2 0 00-1.022-.547l-2.387-.477a6 6 0 00-3.86.517l-.318.158a6 6 0 01-3.86.517L6.05 15.21a2 2 0 00-1.806.547M8 4h8l-1 1v5.172a2 2 0 00.586 1.414l5 5c1.26 1.26.367 3.414-1.415 3.414H4.828c-1.782 0-2.674-2.154-1.414-3.414l5-5A2 2 0 009 10.172V5L8 4z\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Sensibilisateur DAS<\/div><div class=\"pval\">Diazidostilbene en poudre <em>\u2014 diluer \u00e0 10% dans de l’eau distill\u00e9e avant usage<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><circle cx=\"12\" cy=\"12\" r=\"5\"\/><path d=\"M12 1v4M12 19v4M4.22 4.22l2.83 2.83M16.95 16.95l2.83 2.83M1 12h4M19 12h4M4.22 19.78l2.83-2.83M16.95 7.05l2.83-2.83\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Pigments<\/div><div class=\"pval\">Aquarelles haute qualit\u00e9 en tube <em>\u2014 Noir de fum\u00e9e, Bleu de Prusse, Terre d’Ombre<\/em><\/div><\/div>\n <\/div>\n <\/div>\n\n <div class=\"slabel\">Pourquoi l’aquarelle en tube ?<\/div>\n <div class=\"tip\"><strong>Pigments broy\u00e9s fins :<\/strong> l’aquarelle contient des pigments extr\u00eamement fins d\u00e9j\u00e0 m\u00e9lang\u00e9s \u00e0 de la gomme arabique. Cela permet une dissolution parfaite dans la g\u00e9latine chaude, sans grains ni grumeaux qui g\u00e2cheraient la nettet\u00e9 de l’image. Les gouaches ou peintures acryliques sont \u00e0 \u00e9viter.<\/div>\n\n <div class=\"slabel\">Choix du pigment \u2014 teinte & atmosph\u00e8re<\/div>\n <div class=\"pigments\">\n <div class=\"pig-row\">\n <span class=\"pig-dot\" style=\"background:#2a2a2a\"><\/span>\n <div><div class=\"pig-name\">Noir de fum\u00e9e<\/div><div class=\"pig-effect\">Rendu neutre et velout\u00e9 \u2014 profondeur maximale<\/div><\/div>\n <span class=\"pig-badge\">Ombres<\/span>\n <\/div>\n <div class=\"pig-row\">\n <span class=\"pig-dot\" style=\"background:#1a3a6a\"><\/span>\n <div><div class=\"pig-name\">Bleu de Prusse \/ Outremer<\/div><div class=\"pig-effect\">Atmosph\u00e8re nocturne froide \u2014 esprit pictorialiste<\/div><\/div>\n <span class=\"pig-badge\">Ambiance<\/span>\n <\/div>\n <div class=\"pig-row\">\n <span class=\"pig-dot\" style=\"background:#6b4a2a\"><\/span>\n <div><div class=\"pig-name\">Terre d’Ombre<\/div><div class=\"pig-effect\">Aspect s\u00e9pia \/ ancien \u2014 proche du tirage platine chaud<\/div><\/div>\n <span class=\"pig-badge\">Vintage<\/span>\n <\/div>\n <\/div>\n\n <div class=\"tip\"><strong>Le m\u00e9lange Steichen :<\/strong> ne mettez pas 2 g de noir pur. Essayez <strong>1,5 g de Noir de fum\u00e9e + 0,5 g de Bleu de Prusse<\/strong>. C’est ce m\u00e9lange qui donne cette profondeur \u00ab\u00a0nuit profonde\u00a0\u00bb si caract\u00e9ristique de Midnight \u2013 Lake George.<\/div>\n\n <div class=\"inner-sep\"><\/div>\n <div class=\"slabel\">Support et outillage<\/div>\n <div class=\"params\">\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><rect x=\"3\" y=\"3\" width=\"18\" height=\"18\" rx=\"2\"\/><path d=\"M3 9h18M3 15h18\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Papier aquarelle<\/div><div class=\"pval\">300 g\/m\u00b2 minimum <em>\u2014 Arches, Fabriano ou Saunders Waterford<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M3 3l7 7M10 10l4 4M14 14l7 7\"\/><path d=\"M5 5a10 10 0 0 1 14 14\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Application<\/div><div class=\"pval\">Pinceau large Spalter ou tige en verre (Puddle Pusher) <em>\u2014 \u00e9viter les pinceaux synth\u00e9tiques fins<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><circle cx=\"12\" cy=\"12\" r=\"9\"\/><path d=\"M12 7v5l3 3\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Source UV<\/div><div class=\"pval\">Insoleuse \u00e0 tubes actiniques ou LED UV <em>\u2014 ou soleil direct (moins reproductible)<\/em><\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s1\">\n <button class=\"sec-trigger\" onclick=\"toggle('s1')\">\n <span class=\"sec-num\">2<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">La recette de la solution sensible<\/span>\n <span class=\"sec-sub\">Dosages pr\u00e9cis pour 100 ml de solution<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">La pr\u00e9cision du dosage est d\u00e9terminante. Pr\u00e9parez toujours votre solution sous lumi\u00e8re att\u00e9nu\u00e9e (lumi\u00e8re tungst\u00e8ne ou ambre) \u2014 le DAS est sensible aux UV d\u00e8s sa dissolution.<\/p>\n\n <div class=\"slabel\">\u00c9tape A \u2014 Pr\u00e9parer la g\u00e9latine (10%)<\/div>\n <div class=\"recette\">\n <div class=\"recette-head\">Base : 100 ml de solution<\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">90 ml<\/div><div class=\"r-desc\">Eau distill\u00e9e froide <em>\u2014 verser en premier dans le r\u00e9cipient<\/em><\/div><\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">10 g<\/div><div class=\"r-desc\">G\u00e9latine <em>\u2014 saupoudrer, laisser gonfler 20\u201330 min sans remuer<\/em><\/div><\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">40\u201345\u00b0C<\/div><div class=\"r-desc\">Bain-marie <em>\u2014 fondre doucement en remuant pour \u00e9viter les bulles<\/em><\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">\u00c9tape B \u2014 Colorer et sensibiliser<\/div>\n <div class=\"alert\"><strong>Lumi\u00e8re att\u00e9nu\u00e9e obligatoire<\/strong> \u2014 r\u00e9aliser cette \u00e9tape sous lumi\u00e8re tungst\u00e8ne ou ambre uniquement. Le DAS r\u00e9agit aux UV ambiants.<\/div>\n <div class=\"recette\">\n <div class=\"recette-head\">Ajouts \u00e0 la g\u00e9latine fondue (40\u00b0C)<\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">1 \u00e0 2 g<\/div><div class=\"r-desc\">Aquarelle en tube <em>\u2014 1g = gris subtil (premi\u00e8re couche), 2g = noir dense (ombres)<\/em><\/div><\/div>\n <div class=\"recette-row\"><div class=\"r-qty\">10 ml<\/div><div class=\"r-desc\">Solution DAS \u00e0 10% <em>\u2014 ajouter en dernier, m\u00e9langer doucement<\/em><\/div><\/div>\n <\/div>\n\n <div class=\"tip\"><strong>Ratio pigment \/ g\u00e9latine :<\/strong> trop de pigment bloque les UV \u2014 la base ne durcit pas et l’image se d\u00e9colle au d\u00e9veloppement. Trop peu de pigment = image plate sans vigueur dans les noirs. La fen\u00eatre 1\u20132 g \/ 100 ml est votre zone de travail.<\/div>\n\n <div class=\"slabel\">Encollage pr\u00e9alable (secret des blancs purs)<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">Pr\u00e9parer une solution de <strong>g\u00e9latine pure \u00e0 3%<\/strong> (sans pigment ni DAS)<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">Appliquer sur le papier sec avant toute sensibilisation <em>\u2014 cela bouche les fibres et emp\u00eache le pigment de tacher les zones qui doivent rester blanches<\/em><\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">Laisser s\u00e9cher compl\u00e8tement avant le couchage sensible<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s2\">\n <button class=\"sec-trigger\" onclick=\"toggle('s2')\">\n <span class=\"sec-num\">3<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">Le processus de cr\u00e9ation<\/span>\n <span class=\"sec-sub\">Couchage, exposition UV, d\u00e9veloppement<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">Trois phases distinctes : le couchage (en obscurit\u00e9), l’exposition UV (avec le n\u00e9gatif contact), et le d\u00e9pouillage \u00e0 l’eau chaude qui r\u00e9v\u00e8le l’image en faisant fondre la g\u00e9latine non durcie.<\/p>\n\n <div class=\"slabel\">Couchage & s\u00e9chage<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">\u00c9talez votre m\u00e9lange g\u00e9latine + pigment + DAS sur le papier sec avec le Spalter. <strong>Travaillez rapidement<\/strong> \u2014 la g\u00e9latine fige vite.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">S\u00e9chage en <strong>obscurit\u00e9 totale<\/strong>, \u00e0 plat ou suspendu. Ne pas utiliser de s\u00e8che-cheveux (cr\u00e9e des bulles).<\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">Temps d’exposition UV \u2014 r\u00e9f\u00e9rences<\/div>\n <div class=\"expo-bars\">\n <div class=\"expo-row\">\n <div class=\"expo-lbl\">Insoleuse UV (actinique)<\/div>\n <div class=\"expo-bar-wrap\"><div class=\"expo-bar\" style=\"width:55%\"><\/div><\/div>\n <div class=\"expo-val\">8\u201315 min<\/div>\n <\/div>\n <div class=\"expo-row\">\n <div class=\"expo-lbl\">Plein soleil \u00e9t\u00e9 (11h\u201315h)<\/div>\n <div class=\"expo-bar-wrap\"><div class=\"expo-bar\" style=\"width:35%\"><\/div><\/div>\n <div class=\"expo-val\">5\u201310 min<\/div>\n <\/div>\n <div class=\"expo-row\">\n <div class=\"expo-lbl\">Soleil voil\u00e9 \/ hiver<\/div>\n <div class=\"expo-bar-wrap\"><div class=\"expo-bar\" style=\"width:90%\"><\/div><\/div>\n <div class=\"expo-val\">20\u201345 min<\/div>\n <\/div>\n <div class=\"expo-row\">\n <div class=\"expo-lbl\">Couche \u00e9paisse +30%<\/div>\n <div class=\"expo-bar-wrap\"><div class=\"expo-bar\" style=\"width:70%;background:#854f0b;opacity:.6\"><\/div><\/div>\n <div class=\"expo-val\">+30%<\/div>\n <\/div>\n <\/div>\n <div class=\"tip\"><strong>Pigment noir :<\/strong> le Noir de fum\u00e9e bloque davantage les UV que les pigments bruns ou bleus. Augmentez le temps de 20 \u00e0 30% si votre m\u00e9lange est tr\u00e8s sombre.<\/div>\n\n <div class=\"slabel\">La bande d’essai (m\u00e9thode indispensable)<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">D\u00e9coupez une bande de papier sensibilis\u00e9. Placez votre n\u00e9gatif dessus.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">Cachez 80% de la bande avec un carton opaque. Exposez <strong>4 minutes<\/strong>.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">D\u00e9calez le carton pour d\u00e9couvrir une nouvelle section. Exposez <strong>4 minutes de plus<\/strong>. R\u00e9p\u00e9tez jusqu’\u00e0 la fin.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">4<\/div><div class=\"stxt\">Apr\u00e8s d\u00e9veloppement : vous avez des zones \u00e0 4, 8, 12, 16, 20 min. La zone id\u00e9ale = hautes lumi\u00e8res d\u00e9taill\u00e9es sans bavures dans les noirs.<\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">D\u00e9pouillage (d\u00e9veloppement)<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">Immerger dans l’<strong>eau froide 2 minutes<\/strong> \u2014 \u00e9vacue le surplus de DAS non expos\u00e9.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">Passer dans une cuvette d’<strong>eau chaude 38\u201340\u00b0C, face vers le bas<\/strong> \u2014 la g\u00e9latine non durcie fond et r\u00e9v\u00e8le les hautes lumi\u00e8res.<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">Rin\u00e7age final \u00e0 l’eau froide. S\u00e9chage \u00e0 plat sur une surface non absorbante.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s3\">\n <button class=\"sec-trigger\" onclick=\"toggle('s3')\">\n <span class=\"sec-num\">4<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">Obtenir le rendu Steichen<\/span>\n <span class=\"sec-sub\">Cyanotype de fond, multicouche, aspect mat<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">La profondeur l\u00e9gendaire de Midnight \u2013 Lake George vient de trois techniques superpos\u00e9es. Chacune apporte une dimension distincte : la vibration chromatique, le relief physique et la matit\u00e9 velout\u00e9e.<\/p>\n\n <div class=\"slabel\">1 \u2014 Le fond cyanotype : la vibration chromatique<\/div>\n <div class=\"tip\"><strong>Pourquoi \u00e7a fonctionne :<\/strong> le cyanotype s’impr\u00e8gne dans les <em>fibres<\/em> du papier, alors que la g\u00e9latine reste en <em>surface<\/em>. Cela cr\u00e9e une sensation de profondeur spatiale : le bleu semble venir de \u00ab\u00a0derri\u00e8re\u00a0\u00bb l’image. Dans les ombres port\u00e9es par la g\u00e9latine noire, des \u00e9clats de Bleu de Prusse apparaissent \u2014 l’atmosph\u00e8re de nuit \u00e9lectrique typique de Steichen.<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">R\u00e9alisez un tirage cyanotype classique (Citrate de fer ammoniacal + Ferricyanure de potassium) <em>\u2014 proc\u00e9d\u00e9 d\u00e9crit dans notre article sur les virages<\/em><\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\"><strong>Sous-exposez volontairement<\/strong> \u2014 on cherche une image fantomatique, tr\u00e8s claire, qui servira de guide color\u00e9<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">Rincez et laissez s\u00e9cher <strong>24h minimum<\/strong> \u2014 le bleu fonce l\u00e9g\u00e8rement en s’oxydant \u00e0 l’air<\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">2 \u2014 La multicouche : relief et densit\u00e9<\/div>\n <div class=\"layers-schema\">\n <div class=\"recette-head\">Ordre de superposition des couches<\/div>\n <div class=\"layer-row\">\n <div class=\"layer-num\" style=\"background:#1a3a6a\">C<\/div>\n <div class=\"layer-color\" style=\"background:#1d4a7a\"><\/div>\n <div>\n <div class=\"layer-title\">Fond cyanotype<\/div>\n <div class=\"layer-detail\">Dans les fibres \u2014 vibration bleue des ombres<\/div>\n <\/div>\n <\/div>\n <div class=\"layer-row\">\n <div class=\"layer-num\" style=\"background:#4a6a55\">1<\/div>\n <div class=\"layer-color\" style=\"background:#8a9a8a\"><\/div>\n <div>\n <div class=\"layer-title\">Couche 1 \u2014 D\u00e9tails (gris-bleu)<\/div>\n <div class=\"layer-detail\">0,5 g pigment \u2014 exposition longue (12 min) \u2014 hautes lumi\u00e8res et gris moyens<\/div>\n <\/div>\n <\/div>\n <div class=\"layer-row\">\n <div class=\"layer-num\" style=\"background:#2c4a3e\">2<\/div>\n <div class=\"layer-color\" style=\"background:#2a2a2a\"><\/div>\n <div>\n <div class=\"layer-title\">Couche 2 \u2014 Noirs profonds<\/div>\n <div class=\"layer-detail\">2 g Noir de fum\u00e9e \u2014 exposition courte (6 min) \u2014 ombres uniquement<\/div>\n <\/div>\n <\/div>\n <\/div>\n <div class=\"tip\"><strong>Le relief physique :<\/strong> en ajoutant de la mati\u00e8re (g\u00e9latine + pigment) uniquement dans les noirs, votre tirage aura une \u00e9paisseur physique diff\u00e9rente entre les blancs (papier nu) et les noirs (couche \u00e9paisse). C’est ce qui donne l’aspect \u00ab\u00a0objet d’art\u00a0\u00bb caract\u00e9ristique du pictorialisme.<\/div>\n\n <div class=\"slabel\">3 \u2014 Aspect mat : casser la brillance<\/div>\n <div class=\"checks\">\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\">Ajouter <strong>2 \u00e0 5% d’amidon de ma\u00efs (Ma\u00efzena)<\/strong> directement dans le m\u00e9lange liquide \u2014 cr\u00e9e des micro-rugosit\u00e9s invisibles qui diffusent la lumi\u00e8re<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\">Alternative : <strong>silice fumed<\/strong> \u2014 m\u00eame effet, r\u00e9sultat tr\u00e8s proche du tirage platine-palladium<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ko\"><svg viewBox=\"0 0 12 12\"><line x1=\"2\" y1=\"2\" x2=\"10\" y2=\"10\"\/><line x1=\"10\" y1=\"2\" x2=\"2\" y2=\"10\"\/><\/svg><\/div>\n <div class=\"chk-txt\">Vernis mat en finition \u2014 fonctionne mais le fini est moins organique et moins int\u00e9gr\u00e9 \u00e0 la fibre que l’amidon interne<\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s4\">\n <button class=\"sec-trigger\" onclick=\"toggle('s4')\">\n <span class=\"sec-num\">5<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">Le calage \u2014 rep\u00e9rage entre les couches<\/span>\n <span class=\"sec-sub\">Le d\u00e9fi technique de la multicouche<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">Le probl\u00e8me central de la multicouche : entre deux couches, le papier est mouill\u00e9 puis s\u00e9ch\u00e9, ce qui provoque retrait et d\u00e9formation. Repositionner le n\u00e9gatif exactement au m\u00eame endroit est le d\u00e9fi technique principal de la technique Steichen.<\/p>\n\n <div class=\"slabel\">Strat\u00e9gie 1 \u2014 Pr\u00e9-mouillage du papier<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">Avant de commencer quoi que ce soit, <strong>trempez le papier dans l’eau chaude 30 minutes<\/strong><\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">Laissez s\u00e9cher \u00e0 plat <em>\u2014 les fibres sont d\u00e9sormais \u00ab\u00a0stabilis\u00e9es\u00a0\u00bb : le papier ne bougera plus (ou presque) lors des prochains mouillages<\/em><\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">Strat\u00e9gie 2 \u2014 Syst\u00e8me de trous (m\u00e9thode d’atelier)<\/div>\n <div class=\"steps\">\n <div class=\"step\"><div class=\"snum\">1<\/div><div class=\"stxt\">Fixez votre n\u00e9gatif sur le papier avec du ruban adh\u00e9sif repositionnable<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">2<\/div><div class=\"stxt\">\u00c0 l’aide d’une grosse aiguille, percez <strong>deux trous dans les marges<\/strong> (haut gauche + bas droit), traversant \u00e0 la fois le n\u00e9gatif et le papier<\/div><\/div>\n <div class=\"step\"><div class=\"snum\">3<\/div><div class=\"stxt\">Pour chaque couche suivante : alignez les trous du n\u00e9gatif sur ceux du papier \u00e0 l’aide de <strong>deux \u00e9pingles<\/strong> \u2014 le recalage est imm\u00e9diat et pr\u00e9cis<\/div><\/div>\n <\/div>\n\n <div class=\"slabel\">Deux approches du n\u00e9gatif<\/div>\n <div class=\"checks\">\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Approche expert \u2014 plusieurs n\u00e9gatifs :<\/strong> un n\u00e9gatif dense pour les hautes lumi\u00e8res (avec g\u00e9latine peu pigment\u00e9e) + un n\u00e9gatif contrast\u00e9 pour les ombres (g\u00e9latine tr\u00e8s pigment\u00e9e). Contr\u00f4le math\u00e9matique du contraste, sans risque de boucher les blancs.<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Approche Steichen \u2014 un seul n\u00e9gatif :<\/strong> on fait varier le <em>temps d’exposition<\/em> et la <em>charge en pigment<\/em> entre les couches. Plus simple, plus organique, couches qui se fondent naturellement.<\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"sec\" id=\"s5\">\n <button class=\"sec-trigger\" onclick=\"toggle('s5')\">\n <span class=\"sec-num\">6<\/span>\n <span class=\"sec-title-wrap\">\n <span class=\"sec-title\">S\u00e9curit\u00e9 & environnement<\/span>\n <span class=\"sec-sub\">Avantages du DAS vs bichromate<\/span>\n <\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/button>\n <div class=\"sec-body\">\n <p class=\"sec-intro\">L’avantage majeur du DAS est qu’il n’est pas class\u00e9 canc\u00e9rig\u00e8ne, contrairement au dichromate de potassium ou d’ammonium utilis\u00e9 dans la gomme bichromat\u00e9e historique.<\/p>\n\n <div class=\"checks\">\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Non canc\u00e9rig\u00e8ne<\/strong> \u2014 contrairement au bichromate (class\u00e9 CMR : canc\u00e9rig\u00e8ne, mutag\u00e8ne, reprotoxique)<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Plus stable<\/strong> \u2014 le DAS se conserve mieux que le bichromate en solution. Moins de d\u00e9gradation \u00e0 la lumi\u00e8re ambiante (sauf UV directs)<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"chk-txt\"><strong>Gants obligatoires<\/strong> pour \u00e9viter les taches de pigment. Manipuler la poudre DAS avec pr\u00e9caution (masque recommand\u00e9 lors de la pes\u00e9e)<\/div>\n <\/div>\n <div class=\"chk\">\n <div class=\"cico ko\"><svg viewBox=\"0 0 12 12\"><line x1=\"2\" y1=\"2\" x2=\"10\" y2=\"10\"\/><line x1=\"10\" y1=\"2\" x2=\"2\" y2=\"10\"\/><\/svg><\/div>\n <div class=\"chk-txt\">Temps d’exposition plus long qu’avec le bichromate <em>\u2014 8\u201315 min vs 3\u20135 min au bichromate : la patience est le prix de la s\u00e9curit\u00e9<\/em><\/div>\n <\/div>\n <\/div>\n\n <div class=\"tip\"><strong>\u00c9limination des bains :<\/strong> les eaux de d\u00e9veloppement (DAS dilu\u00e9 + pigment) peuvent \u00eatre \u00e9limin\u00e9es dans les eaux us\u00e9es domestiques en petites quantit\u00e9s. Pour des volumes importants, consulter votre d\u00e9chetterie locale.<\/div>\n <\/div>\n <\/div>\n\n <\/div>\n\n \n <div class=\"gd-footer\">\n <span class=\"foot-badge green\">DAS \u2014 non canc\u00e9rig\u00e8ne<\/span>\n <span class=\"foot-badge\">Proc\u00e9d\u00e9 alternatif<\/span>\n <span class=\"foot-badge\">XIXe si\u00e8cle revisit\u00e9<\/span>\n <span class=\"foot-badge\">Contact UV<\/span>\n <\/div>\n\n<\/div>\n\n<script>\nfunction toggle(id) {\n var s = document.getElementById(id);\n s.classList.toggle('open');\n}\n<\/script>\n\n<\/body>\n<\/html>\n","protected":false},"excerpt":{"rendered":"<p>G\u00e9latine-Diazo : L’Alchimie Pictorialiste Proc\u00e9d\u00e9s alternatifs \u2014 Pictorialisme L’Alchimie Pictorialiste :G\u00e9latine-Diazo (DAS) Recr\u00e9er la profondeur mystique des tirages de Steichen \u2014 sans bichromate Multicouche Contact UV Non toxique Niveau interm\u00e9diaire Contexte historique : En 2007, l’analyse scientifique du chef-d’\u0153uvre de Steichen Midnight \u2013 Lake George \u2014 longtemps cru \u00eatre un simple tirage au platine \u2014…<\/p>\n","protected":false},"author":1,"featured_media":4870,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"hide","_kad_post_layout":"normal","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"hide","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[150],"tags":[149],"class_list":["post-4865","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-procedes-photographiques-anciens","tag-gelatine-diazo"],"yoast_head":"\n<title>L'Alchimie Pictorialiste : G\u00e9latine-Diazo - NICOLAS LOUIS<\/title>\n<meta name=\"description\" content=\"D\u00e9couvrez comment recr\u00e9er la profondeur mystique des tirages de Steichen avec la G\u00e9latine-Diazo (DAS). 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