From AI:
To achieve more contrasty results with your wet plate collodion developer, increase the ratio of acetic acid (the restrainer) to ferrous sulfate or slightly decrease your exposure while extending development. A highly concentrated or "hot" developer applied with aggressive agitation will also boost highlight contrast.
Specific techniques and formulation adjustments you can use to tailor your wet plate contrast include:
1. Adjust Your Developer Formula
- Increase Acetic Acid: The acid acts as a restrainer. Increasing the amount of 28% or glacial acetic acid in your ferrous sulfate developer holds back shadow details and creates punchier contrast.
- Reduce Water: Using less distilled water creates a more concentrated (stronger) developer.
- Standard Old Workhorse Recipe (High Contrast):
- 30 to 45 grams Ferrous Sulfate
- 30 to 45 ml Glacial Acetic Acid (or 45 to 60 ml of 28% Acetic Acid)
- 30 to 45 ml Ethanol or 190-proof Grain Alcohol
- 500 ml Distilled Water
2. Exposure and Development Tweaks (Push/Pull)
- Underexpose and Overdevelop: To get brilliant, "dead" whites and deep shadows, slightly underexpose your plate and leave it in the developer longer.
- Use a Metronome: Development time is your primary contrast control. Longer development times (e.g., pushing to 18–25 seconds) will aggressively build up highlight densities. [1]
3. Add a Restrainer (Sugar)
- Lea's Sugar Formula: Adding sugar (or honey/sucrose) to your developer acts as a powerful restrainer. This allows you to develop the plate for longer periods without the background fogging, resulting in richer, more separated tones.
4. Collodion and Bath Conditions
- Aged Collodion: Older collodion that has turned red/amber is generally less sensitive to light. If you use standard exposure times with old collodion, the plate will naturally become underexposed, resulting in a more contrasty image.
- Silver Bath: A slightly more acidic silver nitrate bath (lowered pH) yields cleaner, more contrast-rich plates (less prone to chemical fog).
