Wet Plate Collodion Chemistry Reference
This page covers the chemicals used in wet plate collodion, their hazards, preparation, and disposal requirements.
Collodion — The Carrier
Nitrocellulose dissolved in ether and alcohol — flammable, handle carefully.
Collodion — The Carrier
Collodion is a solution of guncotton (nitrocellulose) in diethyl ether and ethanol. It is highly flammable — keep all flame and sparks away. Store in a sealed glass bottle away from heat. Salted collodion has potassium iodide and potassium bromide added to sensitize it to the silver nitrate bath. Buy pre-salted from a wet plate supplier.
Silver Nitrate — The Sensitizer
10% solution in distilled water — stains everything permanently.
Silver Nitrate — The Sensitizer
Dissolve 100g of silver nitrate in 900ml of distilled water for a 10% bath. Use only glass containers — metal reacts with AgNO3. Maintain the bath pH at 4 to 5 with a small amount of nitric acid. Test with pH strips before each session. A bath that has been used many times accumulates contaminants — filter periodically through a coffee filter. Store in a dark bottle away from light.
Pyrogallic Acid Stains Permanently Pyrogallic acid (the developer) oxidizes rapidly on skin contact and stains brown-black permanently. Wear gloves at all times when handling it. Mix fresh developer for each session — it degrades rapidly once diluted. Prepared pyrogallic acid solution keeps only a few hours.