Using Benzotriazole

[rjphil]

I have been processing a large number of b/w film from a photographer's estate for a retrospective, some of which is high speed (TMZ 3200) and some older Tri-x which is fogging. Mixed up some fresh Benzotriasole and found a test time/dilution in HC110 dilution B that works well. After the Benzo sat for about 2 hours, a white precipitate? formed that looks like cotton wool. It will not dissolve back. Any ideas what this might be? Thought about filtering it out. I have ordered some Moerdsch Restrainer (liquid) in the meantime. Thanks

[PRJ]

That is the Benzo. If you heat it you can get it to dissolve again, but it will separate again.

I am having the same issue with the last batch of Benzo I got from the formulary. I think next time I mix it I'll put it in alcohol. Right now I just shake it up and use it. It works well enough.

[Drew Wiley]

Just how much of it were you mixing in? It doesn't take much to get the job done. A 1% solution is plenty strong as a stock solution; and it only takes a small amount of that in the actual developer.

[rjphil]

I mixed 10 grams of Benzo in 500ml of hot water per directions for stock solution, then used 15ml in a liter of developer (HC110, dil B). The "cotton wool" was in the remaining stock solution, not the developer.

[Doremus Scudder]

It would appear that your benzotriazole is coming out of solution. The "cotton wool" state is common for benzotriazole.

Try mixing a weaker solution, i.e., 5 grams benzotriazole in 500ml total solution (a 1% solution) and see if that doesn't help. Also, be sure to use distilled water; any impurities in tap water can cause it to hold less dissolved chemical, especially when making strong solutions.

Best,

Doremus