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tb001

Old Chemicals

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I'm finally nearing the end of the renovation of my studio space and starting to dig through the boxes of old materials I have in storage. Right before I packed everything up, I also bought a used kiln and ton of supplies on craigslist from a potter who was shutting down her studio.

 

As I'm opening up boxes and boxes of glaze chemicals, I'm wondering if any of the basics have a shelf life. Everything looks ok, with the exception of the zinc oxide being a little chunky...

 

Also, I know things can change in a mine over time. My chemicals are at least 5+ years old. The ones I bought from her I'm guessing could be 5-10 yrs old. Have there been any major changes in particular chemicals over that time? I'll be doing a ton of glaze testing and would prefer not to optimize a glaze for a chemistry I can't get anymore!

 

So excited to finally be close to having a functional studio again!

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I'm using materials I got in the 70's still-They work great. Your materials do not go bad.

The zinc just absorbed moisture and will be fine. You can beat it up  in chunks and what I use when mixing zinc in glazes is a junker shop blender.Blend some water with the zinc and add into the mix after blending the zinc and water.

Yes as the earth is mined the materials change slightly. No worries

There are a few exceptions like Custar feldspar has changed some but use up what you have.Its not rocket science just glaze.

The shelf life is a few lifetimes or longer for most materials.

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I agree with Mark. I have a lot of chemicals that are 15, 20 40 years old. They seem to be fine to me. Cornwall stone has changes but fires the same IMO.

Zinc , as mark says, can absorb moisture. Some glazes change after they have been put into liquid , if they are water soluble. But that is not from age, it is from the soluable chemicals evaporating.

 

Marcia

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Ah, Custer feldspar is the one I was thinking of I think. Any idea roughly when this changed? Any others I should be aware of? Love to experiment w glaze formulations, but just don't want to end up having a glaze I love that I can't replicate because I can't get one of the components anymore.

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you have not said how much of the chemicals you recieved?  a few pounds or a nearly full 50 lb bag?

 

chemists among us, would mixing the old with the new and stirring it around help balance out any changes between old and new?

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Ah, Custer feldspar is the one I was thinking of I think. Any idea roughly when this changed?     1999, and again in  late 2008. Was 10% potassium: runs 5-7 now.

Calcine your zinc to 1800F, burn off the molecular water as well. Sieve back to dust.

 

Nerd

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Thanks glazenerd--this is exactly what I was trying to figure out! Once I get fully up and running will try calcining the zinc as well.

 

I used to be a scientist in a former life, so am used to the concept of most chemicals not going bad, with the exception of those that absorb water or are light sensitive or especially unstable, but I'm also used to the chemical composition being exactly what it says on the bottle!

 

I love glaze testing and plan on doing a fair bit of experimenting, so want to be able to repeat my experiments when I need to refresh ingredients. I'd love to try some of the crystalline glazes and, if it's anything like lab experiments, the fewer variables the better.

 

Old lady, I mostly have 5-10lb bags, other than the basics like silica. So enough to do a fair amount of testing. For most things it sounds like probably doesn't matter too much, which is great!

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Guest JBaymore

...............but I'm also used to the chemical composition being exactly what it says on the bottle!

 

Studio ceramics is going to drive you nuts!  ;)

 

best,

 

...............john

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rocks are millions of years old already, a few more won't matter

 

 

But how can you be sure?  What if One million and one years is the limit?!!!...Hehe....

 

 

You can tell a rock is out of date if it has turned into clay ;) but then it is in date for clay  

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rocks are millions of years old already, a few more won't matter

 

Does granite decompose and turn into china clay because it is too old to stay as granite, or is it because it was poorly made in the first place?

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rocks are millions of years old already, a few more won't matter

 

Does granite decompose and turn into china clay because it is too old to stay as granite, or is it because it was poorly made in the first place?

 

 

It is something to do with slightly acidic water disassociating the KNa and some Si from the feldspars and making/leaving kaolin.

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