Does anybody know if old patina can go bad in the bottle? I've got a few universals and traditionals, etc. that haven't been used for a few years. Some have never even been opened. I know some like liver of sulfur go bad after they are mixed.
Would depend on the chemicals, and its heat,lights air tolerance. They do have shelf lives when as you say are mixed and the then the clock starts ticking. Mostly do to exposure and the start of the oxidation or decomposition of the chemicals once they are introduced to air/oxygen/ nitrogen,heat and light. If the bottles are tightly capped, and kept in a cool dark place they will be good for a while. With out knowing the exact materials or mixes. A general rule can only apply,
When mixed depending on the above and the strength of the solution. They do have a shorter shelf life, dark bottles to keep out sunlight, and good seal in the cap and a moderate temperature storage. just like in the Goldie locks story. not to hot not to cold but just right. So don't leave them in the unheated studio.
If they haven't been opened, I would try them out on some test panel strips. And see what happens, always cap them after pouring out what you need. As not only the liquid materials are at risk but the solid or lump materials can start to decompose too.
I have some I've been using for years. Some of the liquid ones can certainly separate and be difficult to mix back up. Guess you should try them and see how they work!
Yes... I nominate Tony to be the official "old patina tester" and get back to us on their performance. I have quite a few bottles that fall into that category also and have wondered about it.
(03-28-2010 07:18 AM)Scratch Wrote: [ -> ]Yes... I nominate Tony to be the official "old patina tester" and get back to us on their performance. I have quite a few bottles that fall into that category also and have wondered about it.
Yes, send them to me. In the old days I loved to experiment with chemicals.
.gif "Laugh")
Here are a couple of PDF files, that will throw, so light on the subject.
A letter from Fisher chemicals
This next one will probably more useful as it list some chemicals and also the acceptable definitions of the assorted terms used in the chemical industries.
6 page PDf download list of chemical shelf life
Now the storage color code is based on families of chemicals/materials that are safe to store together.
It also lists it if it hazardous, and what the hazard is.
And by the common name.
Here is the parent site that the above came from.
It has other safety info, as it is an Irish teachers site.
Here is their Material Safety Data Sheets
Tony, I bought one of the sample kits over 10 years ago. Most of the labels on the bottles have faded so kind of guessing what is in them. They still work but as Shawn said they are tough to get mixed up because of separation. Might have little chunkies in them.
Thanks all. I'm not really having a problem with them yet. It's just something I thought of the other night while browsing the cabinet. Guess I won't try to use them up just because they may go bad.