so - there i was mixing up a batch of van dyke sensitizer for the first time. everything was going fine. i was well warned of adding the silver nitrate to the ferric ammonium/citrate tartaric acid solution very slowly. drop by drop with constant stirring. i checked the mix when i had droped about 50ml of the silver nitrate into the ammonium/citrate tartaric acid solution. everything look fine - then some where about the 25ml mark i checked the solution again and noticed it was a lighter shade of green. i stopped stirring to let the mixture settle and noticed the parcipitate in the bottem of the beaker. i had been dripping the silver nitrate into the ammonium/citrate tartaric acid solution for at least 45minutes. where did i go wrong?
BTW - i was mixing under very low lighting in my darkroom. room and water temp was around 68f and i used distilled water to mix all the chemicals.