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I have several large bags of glaze chemicals that for various unexpected and unknown reasons, have lost their labels. After narrowing down the possibilities by visual examination, can anyone suggest how I might determine more definitely what they are? 

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Fire a little glob of each on a tile and compare it to a fired glob of known materials. Some will be pretty obvious, like magnesium carbonate. Others will not, like you probably won't be able to tell the difference between different types of potash spars. If you're not 100% sure, try firing it in a glaze recipe test and see if it comes out the same.

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Color might help. If they are white or grey they could be feldspar, frits, or clay. If they are colored they might be pigments.  Try a dropping a little into a few ounces of vinegar on each one. If it fizzes a lot and completely  goes into solution, then it is probably a carbonate of some sort. If not, it could be a frit or a feldspar.

 

get a piece of of nichrome ( old kiln element wire) or iron wire and dip it in the vinegar solution of the unknown.. put it in the flame of a propane torch. If it burns red you may have lithium or strontium.  If it burns green, you have copper or barium.  Most frits and feldspar's will show a yellow sodium color. potassium feldspar might show violet tones but might be obscured by the much stronger yellow sodium color.

 

Then follow Neils advice.

 

Also hope like hell that you don't use these unknowns and come up with a glaze that is a total knockout... you may not ever be able to reproduce it after you run out of whatever you used to make it.

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Guest JBaymore

 

What are the odds that this is going to end well?

 

It would be cheaper from a time management standpoint to thrown them all out and buy new chemicals.

 

 

 

But until you know what they are.......... "throwing them out" can be a bit of a legal (or at least moral) issue.  ;)

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What are the odds that this is going to end well?

 

It would be cheaper from a time management standpoint to thrown them all out and buy new chemicals.

 

 

 

But until you know what they are.......... "throwing them out" can be a bit of a legal (or at least moral) issue.  ;)

John

 

True. Hazardous waste folks would charge a lot to do the testing to find out if they are hazardous. Start firing. I had 50 #  of frit that lost its label in my studio move.. I  test fired with a brush stroke of copper underneath and could compare the resoles with other frits fired the same way. I figured it out. Frits are expensive and worth the time.

Marcia

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I agree with Chris. This is not going to end well. Not worth the time to test everything, and a huge potential for mistakes. This is why it is important to place your chemicals in well marked plastic containers. There are so many white powders.

TJR.

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I have several large bags of glaze chemicals

Seems like you could narrow things down. If large means more than about 25 pounds, they are probably major glaze chemicals like feldspar's and whiting, or silica.

 

Did you inherit these things or did the labels of what you already had fall off? If these were materials you already had, then maybe you should determine what materials you still can identify and this will eliminate some possibilities.

 

Still, you will not really know what you have without a real chemical analysis which is out of the question. 

 

I'm all for giving it a shot and testing them out as Neil and Marcia suggested.

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Guest JBaymore

Chris,

 

If you are a pottery business... those "household hazardous waste days" are not legal to use.

 

You might get away with it.... but if not ... whopping fine.

 

My general tip on getting a nice big "donation" of a lot of old materials from someone........... don't unless in original bags or very well labeled containers.

 

Good way to get RID of some old pottery chemicals you don't want to deal with.... find someone else to take the "donation".  ;)

 

 

 

best,

 

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

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What are the odds that this is going to end well?

I too see that no good can come from this.

 

The studio I'm a member of acquired a bunch of old chemicals, fortunately 99% was clearly marked or in original packaging.(lucky)

 

I suppose if you gave the chemicals to your friends in 5 pound lots you could probably get away with household haz mat waste day....

 

Do you have any friends that are chemists?

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Thanks to all of you for taking the time to help me out with all this advice!

They mystery white powders are over 20 lbs or so and yes, that does narrow it down quite a bit. I did inherit these, though they were labeled at the time or I wouldn't have taken them. It could be they were masking tape labels that got old and fell off. I had a flood here a few years ago (somewhat alarming when the river suddenly comes through your front door on a dark night when you can't see what's happening! It turned out to be caused by a several km long ice jam but that's another story;-) and there was a mad rush of throwing large heavy sacks among other things upstairs. I kept what stayed dry but suspect that might be when the labels disappeared. I would really rather not throw them out so will try these suggestions and then probably try the narrowed down results in small batches of glaze. 

Kathy

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