wet plate chemistry shelf life

[Jersey Vic]

Hey wet-platers;

It's been a couple of years since I mixed up any collodion, developer, varnish etc and I'm wondering which if any of my unmixed chemsitry might have gone bad?

Also, what are the chances I can still use my mixed varnish and (please God) silver bath?

Thanks in advance for your knowledge and help.

Victor

 

[smieglitz]

Salted collodion can go bad and the color gives an indication. "Old red" collodion loses speed and gains contrast. It will either work or not, depending on the formula. Cadmium-based formulas hold up the longest, ammonium the least. If it works, OK then. If not, it may improve results with fresh collodion if you add a bit (10% or so) to the new stuff.

Ether has a shelf life due to the potential formation of explosive peroxides. Under ideal conditions, many institutions have 3-6 months listed as maximum storage periods before the stuff should be disposed of.

The developer might oxidize over time. That could be a good thing. Try it. Or, don't worry and toss it. It is the cheapest part of the process.

If any alcohol has evaporated from the varnish, you might have to add a little to bring it back to the proper viscosity, but otherwise it should be OK AFAIK.

I'd suspect the silver bath would also hold up. Some strength may have been lost if it plates out on the bottle, but otherwise get the specific gravity back to normal and it should be OK. The silver nitrate is only light-sensitive in the presence of organics, so filter it and bring it back to a 9% solution and you should be good to go.

 

[nawagi]

Chuck everythiing except raw chemicals, the varnish and your silver bath. I've been using two silver baths alternately since 1999 (with sunning, AgNO3 replenishment) and they are fine. I have used varnish well over a year old - also fine. Smi. is right about possible evaporation from the varnish- though mine was sealed in a canning jar it it was ok. Old ether is the real hazard- peroxides may explode. Old collodion can be used to age your new mix, but don't go crazy- I add 50 ml to a 450 ml batch tops.

NWG

 

[Jersey Vic]

This is excellent info. Just to clarify, my collodion and ether are unmixed. I transfered from the Artcraft cans to brown glass bottles. I'll chuck the ether but shouldn't the unsalted collodion be OK?