the environmental impact balance is strongly in favor of hca.
I try to do my best, but miss it sometimes. Thanks though.
You are right, trial and error is best, and the test for Silver retention is a kit which has Sodium Sulfide in it. It turns yellow, brown or black depending on the level of retained silver.
However, I point you to a thread with the subject the yellowing of prints. This person was using the Ilford method, but had prints that turned yellow quite rapidly. This was also experienced by Ctein who wrote an article on it. You see, water varies world wide, photoproducts vary in thickness and silver level and etc. Therefore it is hard to predict.
In the US we use Chlorine to treat water, but in other parts of the world, they use Ozone for purification. This greatly complicates the situation.
You should run your own quality assurance tests, and be aware that overwashing is as bad as underwashing.
Go here for the MSDS of HCA : https://www2.itap.purdue.edu/msds/docs/9725.pdf
The working solution is up to 50 g/l Na2SO3 which has a very high COD. It ranks up there with some developers and near or below hypo itself! I don't deny it is useful, but rather I argue that if you dump a 1 L tray, you have to contend with normal hypo/silver in wash #1, HCA that you dumped, and HCA / silver in wash #2. It is the hca dumped and wash #2 that I am pointing to. These must be at least handled properly.
PE: Thanks very much, I'll look for a kit with some Na2S. ( I only had a year of chemistry in college, so I'll just follow the directions! )
Our water is from our well, run through a calcite filter and then a water softener ( with KCl instead of sodium ) and finally a reverse osmosis filter. There aren't many dissolved solids after that, but our water is probably different from other places. Testing it will be!
a normalrunning-water wash is perfectly archival, and that's my main concern!