2 Clear: bath of de-chlorinated water (10 l) + citric acid 2-5 mins
It is very important to avoid chlorinated water at this stage, when the silver nanoparticles are still highly vulnerable; use rainwater or water that has been passed through an activated charcoal filter, or been boiled and allowed to stand. Add a tablespoonful (ca. 25 g) of citric acid to each 10 litres of water to scavenge any traces of chlorine, and to provide slight acidity (pH 4). Alternatively use two baths of smaller volume. Change the first bath for each print. Immerse until the yellow stain is cleared.