Process · Platinum/palladium
Calibrate your platinum/palladium before committing the Pt/Pd.
At €5 per A4 sheet and 300+ usable grey levels, calibrating is no longer a comfort. Fifteen minutes of measurement, a 16-point `.acv` curve, and the whole tonal range finally readable.
Article vérifié par Tristan Sidem + Raphaël Lebas de Lacour
Le problème
Sound familiar?
- 01
Tonal range crushed to 150 levels
Platinum/palladium can use 300+ levels. Without calibration your negative uses only half — you pay for palladium to get greys linearised at a loss.
- 02
Shadows blocked in the deep blacks
The 1.8 Dmax of Pt/Pd is never reached without a curve. Shadow detail is lost in a uniform black.
- 03
Cost piling up with every test
Three failed prints = €15 of chemistry + an €8 A4 cotton-rag sheet. Calibration pays for its own session from the second series.
La différence sur un tirage platinum/palladium
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 platinum/palladium.
Spécificités du procédé
Expensive, wide, slow — calibratable in advance.
Platinum/palladium printing relies on the UV reduction of ferric salts, which in turn catalyses the deposition of metallic platinum or palladium in the paper fibre. The result: a print with an exceptionally wide tonal range — about 300+ distinct grey levels used — and museum-grade permanence (several attested centuries).
The chemistry cost is very high: between €4 and €8 per A4 sheet depending on the chosen Pt/Pd ratio and sensitisation dose. At that level, printing blind is not a viable option. Calibrating before each series, or at least at every substantial change of chemistry or paper, becomes an economic condition of the process.
The typical Dmax is 1.8 on Hahnemühle Platinum Rag, a paper formulated specifically for the process. On other heavy cotton papers you get a Dmax between 1.6 and 1.75. The development bath (potassium oxalate or sodium citrate) is temperature-sensitive: 20 °C produces softer highlights, 30 °C lightens them and raises contrast. Calibrate at the temperature you will print at in production.
Target polarity: negative, like all contact-exposure processes (except resinotype). The sensitiser contains a small amount of potassium dichromate as a contrast agent — the dichromate concentration changes your curve’s slope and must be stabilised before calibration.
Lire en détail dans le manuel
Référence externe : Wikipedia
Génère ta mire platinum/palladium 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 on transparency
Negative polarity, no colour management, on the same paper as your final print (Hahnemühle Platinum Rag preferred).
Sensitise, expose, develop at controlled temperature
Pt/Pd + dichromate sensitisation, UV exposure, development at production temperature (20-30 °C). Read after stabilised drying.
Export the .acv curve for Photoshop or Affinity Photo
A 16-point Adobe `.acv` curve, exported in one click, ready to apply to your production negatives.
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 platinum/palladium.
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.
« Platinum/palladium is the process that makes software calibration legitimate. At that chemistry cost, you no longer print on instinct. Calibration Flow does not replace the practitioner’s eye — it preserves the tests you will not redo. »
Références techniques
- Christopher James — The Book of Alternative Processes (chapters 16-18 on platinum and palladium printing)
- Bostick & Sullivan — reference Pt/Pd sensitisers
- Dick Stevens — Making Kallitypes and Platinotypes
- Mark Nelson — PDN method applied to platinum
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 (€449 A4 / €699 A3+)
- 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 |
|---|---|---|---|---|
| Tonal precision | 16 .acv points | Very high | Maximal | Manual |
| 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
For very high-volume production with a closed K7 dedicated-printer flow, PiezoDN remains the reference — but at a high entry and learning cost. CF positions itself as the short path to an `.acv` curve usable in Photoshop without additional hardware.
FAQ
Questions from platinum/palladium practitioners.
- Platinum/palladium costs between €4 and €8 of chemistry per A4 print, sometimes more. At that price, calibrating is not a comfort — it is an economic condition. A Calibration Flow session consumes one A4 sheet + its chemistry (~€5) and gives you an `.acv` curve that, in practice, saves you 3 to 8 failed prints over the following weeks. The return on investment is immediate from the second printing session.
- Yes, appreciably. Pure Pt produces cool greys with a slightly higher Dmax (~1.85 on Hahnemühle Platinum Rag); pure Pd produces warm browns with a Dmax around 1.7. 50/50 or 70/30 mixes produce an intermediate curve. Recalibrate at each significantly different ratio — Calibration Flow keeps a library of ratio-linked curves for quick switching.
- Yes. Platinum development is temperature-sensitive: a 20 °C bath produces softer highlights, at 30 °C the highlights lighten and the Dmax rises slightly. The practitioner rule: calibrate at the temperature you will print at in production. If the season changes (unconditioned workshop), recalibrate. This is documented in detail in the manual page courbe/analyse-tonale.
- Platinum/palladium uses about 300 distinct grey levels between Dmin and Dmax, against 150 to 200 for most hardening processes (cyanotype, gum bichromate). It is this fineness that justifies software calibration: by eye you can place 30 to 50 patches, but Calibration Flow offers an `.acv` curve of up to 16 points that distributes them where the slope changes most — not linearly.
- Dichromate is the contrast agent of platinum/palladium. A higher concentration hardens the curve (more contrast, fewer mid-tones); a lower concentration flattens it (softer greys, less shadow separation). Calibration Flow does not drive the chemistry: it measures the result on your final negative, whatever your dichromate concentration. The generated curve compensates the actual response, not a theoretical one.
Platinum/palladium is not in the Vision Picturale range.
The Picturale ecosystem sells six UV-exposure processes — cyanotype, gum bichromate, carbon, bromoil, gumoil, resinotype. Platinum/palladium 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 Pt/Pd:
- Chemistry — Bostick & Sullivan (historical US reference, complete Pt/Pd kits) and Photographers' Formulary offer ready-to-measure sensitiser + developer kits.
- Paper — Hahnemühle Platinum Rag, Arches Platine, Bergger Cot 320. 100 % cotton, neutral pH, no optical brighteners, 300 gsm+.
- Reading — Christopher James, The Book of Alternative Process Photography, the Pt/Pd chapter with precise ratios and bath times.
- See a reference print — Maison Picturale prints in platinum-palladium in its Paris workshop. Useful to compare your calibration print against a workshop reference.
- Calibration — open Calibration Flow, follow the step-by-step. Your platinum/palladium produces the target, the app generates your curve, your workflow is calibrated within two weeks.
Do you also practise a Vision Picturale process in parallel (cyanotype, gum bichromate, carbon…)? See the six ecosystem processes →
Calibrate before committing the platinum. The economic rule.
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