My original silver nitrate bath dates from the beginning of my collodion time; 2009. I filter the bath before and after every use, every time. A proper taking care of the bath is crucial for your images. And it’s expensive enough to want to take proper care of it. Every now and then it gets so polluted by ‘radicals’ that just filtering won’t do it anymore. I put the flask in the sunlight, cover it with a sheet of toilet paper and let all the nasty things evaporate. Measure pH and density, adjust where needed and it’s good to go. However, after having used this bath for 4 years (issues started last year) it gets so contaminated that sunning won’t do the trick as well. I got these really tiny specks on my plates which I couldn’t trace back to anything else than a heavily polluted silver bath. A conversation with Jeroen confirmed that. So, it was time for some drastic measures 🙂
Boiling! Yeah! So…when you have a solution of silver nitrate of 1 litre, you add distilled water until you have 1.5 litres. Then you boil it back to its original amount, filter, measure, adjust where needed and done! As simple as that 🙂 Well, it is really that simple! Only, where to put it in when boiling? I ordered a 2 litre erlenmeyer flask. I bought a (cheap) cooking plate with too little power. Heating up the solution took more than one hour. I’m easily bored so no thank you 🙂
Next I bought an induction plate with a little bit more balls 🙂 But induction needs inox to function, so no glass. I bought a stainless steel pot and boiled it in that. Went incredibly fast but I simply do not really trust a stainless steel pot for this. So, I decided to fill up the pot with distilled water and place the erlenmeyer holding the silver nitrate solution in it, au bain marie style, so to speak. Two good things: if the glass breaks the pot will keep it from going bye-bye. And by using distilled water for cooking the solution is preserved and not mixed with nasty tap water. It worked very well, except that the erlenmeyer had too small an opening so the boiling went really slow. Next time I will use a wide-mouth erlenmeyer or just a glass beaker that can take some heating. And the baths are perfect again- and the images speck-free!
(oh for the paranoia ones…I removed the cables in the background during the boiling 🙂 )
I’ve been tormenting my silver bath for quite some time now. Finally ought it time to fix it a little. I sunned the bath for a couple of days while having added a tablespoon of bicarb of sodium to help restoring the bath and getting rid of all the organic pollution. This resulted in a lot of sediment so I had to decant the silver nitrate first before starting the filtering. I should have made images of the filter pads before and after, especially before..they were black!
After a lot of filtering the pads finally remained in its clear white condition which told me the bath was okay now. Then it was time to measure specific gravity. It should read about 1.06 / 1.07, mine read about 1.04 / 1.05.
The image on the left is before adding silver, the one on the right after adding the silver. I actually pinched in a bit more silver nitrate after that photo so it should read about 1.07 now.
Measuring the specific gravity you use a hydrometer which reads around the value that you need. You can get one very easily at a (beer or wine) brewer shop for example.
My silver bath is working fine and looking good again!