Process · Van Dyke
Calibrate your Van Dyke — warm, toned or not.
Ferric citrate + silver nitrate, variable purple-brown tone, gold or selenium toning. Two linked `.acv` curves in one project: before toning, after toning. The toner shifts the curve — you need to know it.
Article vérifié par Tristan Sidem + Raphaël Lebas de Lacour
Le problème
Sound familiar?
- 01
Tone drifting between series and toning
The untoned print is warmer than the gold-toned one — without a dedicated curve you lose the predictability of the final rendering.
- 02
Charcoal shadows on alkaline paper
Ferric citrate destabilises in the carbonate reserve of buffered paper. The print loses 0.2 to 0.3 in Dmax in the wash.
- 03
Highlights turning yellow
Poorly calibrated fixing leaves unfixed silver traces that yellow within weeks. Software calibration does not fix this chemical defect — it reveals that it exists.
La différence sur un tirage Van Dyke
Le même fichier source, tiré sans calibration à gauche, calibré avec Calibration Flow à droite. Tu vois directement comment la calibration libère la plage tonale complète de ton procédé Van Dyke.
Spécificités du procédé
Silver purple-brown, sensitive to paper and toner.
Van Dyke (sometimes called Van Dyke brown print or simplified kallitype) produces a warm silver purple-brown print by UV reduction of silver nitrate by ferric ammonium citrate. It is a silver process in the strict sense, unlike cyanotype (pure iron) or platinum/palladium (noble metal).
The typical Dmax is 1.5 to 1.7 depending on paper and the citrate / silver ratio. The process is very sensitive to paper acidity: a buffered alkaline paper (Canson Montval for example) destabilises ferric citrate on contact with its carbonate reserve, and the print loses density in the wash. Neutral or slightly acidic papers (Hahnemühle Platinum Rag, Arches 300 g, Bergger COT 320) remain the reference.
Toning changes the curve. A Van Dyke print can be gold-toned (shift to cool purple-brown, Dmax +0.15 to +0.2), selenium-toned (contrast gain, Dmax +0.1 to +0.2), or left raw (warm brown). At each systematic toning, recalibrate — the `.acv` curve to apply to the negative is not the same whether you tone or not. Calibration Flow keeps the linked curves in a single preset library.
Double exposure (long exposure + partial development + short second exposure) is an advanced technique that raises the Dmax by 0.15 to 0.25. If you practise it systematically, calibrate on it.
Target polarity: negative, like all contact-exposure processes.
Lire en détail dans le manuel
Référence externe : Wikipedia
Génère ta mire Van Dyke maintenant
Mire 25 patchs (grille 5×5 + dégradé continu), paliers d'environ 4.2 % d'intensité, échelle L* CIELAB. Polarité négative (correspond à ce procédé). Télécharge, imprime sur transparent jet d'encre sans gestion de couleur, insole sur ton papier sensibilisé.
Version téléchargée en 1680×1410 px, adaptée à un tirage standard. Pour des dimensions et un nombre de patchs personnalisés, utilise la fonction mire sur mesure de l'app, débloquée avec le code Luminograph.
Mire générée par le même algorithme que l'app (fonction generateSingleMire). Échelle de mesure : luminance perceptuelle L* CIELAB.
Workflow en 3 étapes
Mire, insolation, courbe.
Print the 25-patch negative target
Negative polarity, no colour management. Print on the production paper (Hahnemühle Platinum Rag preferred for the test).
Sensitise, expose, fix, tone (optional)
Ferric citrate + silver nitrate sensitiser. Contact UV exposure, thiosulfate fixing, washing, optional gold or selenium toning.
Export the .acv curve for Photoshop or Affinity
One curve per mode (untoned, gold-toned, selenium-toned if needed). Calibration Flow groups the linked curves in the same project.
Ajuste la courbe en direct
Calibration Flow corrige n'importe quelle réponse non-linéaire avec trois sliders. Pas de point à dessiner à la souris, pas de Bézier à manipuler. Joue avec les valeurs ci-dessous et vois immédiatement l'effet sur la courbe et sur le rendu tonal Van Dyke.
Entrée 0–255 ↔ Sortie 0–255
Seuil d'entrée minimum. Tout ce qui est en dessous devient noir pur.
Seuil d'entrée maximum. Tout ce qui est au-dessus devient blanc pur.
Courbure des tons moyens. 1,00 = linéaire, < 1 = mid-tones sombres, > 1 = mid-tones clairs.
Dégradé source (avant correction)
Dégradé corrigé (après application de la courbe)
Cette démo applique une formule simple (points noir/blanc + exposant gamma) pour l'illustration. L'app utilise en plus un lissage par LOWESS robuste + PCHIP monotone qui arrondit les transitions sans créer d'artefacts. Tu exportes ensuite un fichier .acv chargeable dans Photoshop ou Affinity Photo en deux clics.
Preuve d'autorité
Pourquoi nous faire confiance.
« Van Dyke is the process that teaches you to calibrate in two stages: before toning, after toning. Without that double pass, you print a "before" — and discover the "after" as a surprise. That is exactly what Calibration Flow teaches you to anticipate. »
Références techniques
- Christopher James — The Book of Alternative Processes (chapter 14 on Van Dyke and kallitype)
- Dick Stevens — Making Kallitypes and Platinotypes (practitioner reference)
- Bostick & Sullivan — ferric citrate chemistry
Signé
- Tristan Sidem — founder of Calibration Flow + Vision Picturale
- Raphaël Lebas de Lacour — co-founder of Vision Picturale
Accès & tarif
Essayer Calibration Flow.
Web
Free with account
- Target, Curve, Negative and Library features active
- No credit card required
iOS
€9.90/month
- One month trial included
- iPhone capture
- Cross-device sync via the Web app
Code Luminograph
1 year of Pro included
- Shipped with the purchase of a Luminograph at Vision Picturale
- One year of Pro mode, then reverts to free
- Extended quotas and 500 MB of cloud storage
Comparatif honnête
Calibration Flow face aux alternatives.
| Dimension | Calibration Flow | QuadToneRIP | PiezoDN | Méthode manuelle |
|---|---|---|---|---|
| Toning management | 2 linked curves | Manual | Manual | None |
| Learning curve | ~15 min | ~2 days | ~1 week | Variable |
| Entry price | €0 (free) | ~$50 | ~$300 | ~€400 |
| .acv output | Native | No | No | To be drawn |
| Mobile | ✓ | — | — | — |
Quand choisir un autre outil
QTR keeps an edge for a K7 workflow with a dedicated printer and a single paper. CF stays relevant when the process needs two linked curves (before and after toning) — a case where mobile reading and the preset library make the difference.
FAQ
Questions from Van Dyke practitioners.
- Yes, appreciably. A raw Van Dyke leans towards warm brown (Dmax ~1.5). Gold-toned, it shifts to a cool purple-brown with a Dmax rising to ~1.7. Selenium-toned, it gains a more contrasty grain, with a Dmax that can reach 1.75. The practitioner rule: calibrate the untoned print for your standard production, then recalibrate a second `.acv` curve if you tone systematically. Calibration Flow keeps both curves in the same project for quick switching.
- Van Dyke uses a ferric ammonium citrate + silver nitrate sensitiser. On a buffered alkaline paper, the ferric citrate destabilises in contact with the carbonate reserve, and the image loses density in the wash. Recommended papers have a pH between 5.5 and 7: Hahnemühle Platinum Rag (excellent), Arches Aquarelle 300 g (good), Bergger COT 320 (very good). Avoid papers sized with alkaline gelatin.
- Some practitioners expose in two stages: a first long exposure that reveals the full image, then a short second exposure after partial development that densifies the deep shadows. This technique raises the Dmax by ~0.15 to ~0.25, at the cost of a doubled printing time. If you practise double exposure systematically, calibrate on it — the curve will differ from a single exposure. Calibration Flow accepts any exposure cycle: it measures the result, not the method.
- Three well-tested references: Hahnemühle Platinum Rag (neutral pH, long cotton fibre, very clean for Van Dyke), Arches Aquarelle 300 g satin grain (neutral pH, common paper, Dmax 1.55 reached), Bergger COT 320 (dedicated alt-process paper, no whitening agent). To avoid: Canson Montval (too buffered), Rives BFK (variable batch to batch for Van Dyke). Maison Picturale keeps a validated selection for this process.
- No. Van Dyke specifically uses ferric ammonium citrate, which reacts with silver nitrate to produce purple-brown metallic silver. Platinum/palladium uses ferric oxalate (sometimes iron citrate for the nearby kallitype) which in turn reduces platinum or palladium. The two sensitisers are neither interchangeable nor mixable — they are two distinct chemistries for two distinct processes.
Van Dyke Brown is not in the Vision Picturale range.
The Picturale ecosystem sells six UV-exposure processes — cyanotype, gum bichromate, carbon, bromoil, gumoil, resinotype. Van Dyke stays outside it. Calibration Flow calibrates it anyway, independently of your chemistry or paper supplier. You import your scanned target like for any alt-process, export your .acv curve, and apply it in Photoshop before your print.
A few references if you are starting Van Dyke:
- Chemistry — Bostick & Sullivan and Photographers' Formulary offer ferric ammonium citrate + silver nitrate + thiosulfate fixer kits, measured to the gram. Freestyle Photo (US) also resells ready kits.
- Paper — Arches Platine, Hahnemühle Platinum Rag, Bergger Cot 320. Prefer slightly acidic to neutral papers — an alkaline paper attacks the silver image in the wash.
- Toning — gold bath (sodium gold chloride) for stabilisation and deep purple toning, or selenium bath for warmer tones. Toning changes your curve — recalibrate after a toner change.
- Reading — Christopher James, The Book of Alternative Process Photography, the Van Dyke / Kallitype / argyrotype chapter.
- See a reference print — Maison Picturale prints in Van Dyke in its Paris workshop, with or without toning. Useful to compare your calibration print against a workshop reference.
- Calibration — open Calibration Flow, follow the step-by-step. Target print, scan, measurement,
.acvcurve — the same workflow as for a cyanotype, just a different tonal ramp.
Do you also practise a Vision Picturale process in parallel (cyanotype, gum bichromate, carbon…)? See the six ecosystem processes →
Calibrate before toning. And after, too.
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