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"Snow White 04-6" Bag-o-powder


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#1 blacknapkins

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Posted 31 January 2013 - 06:57 PM

Hello! I have just taken about 30 lbs of powder home from an estate sale labeled "Snow White 04-6".

Is there any way of finding out who makes this glaze? I have checked the whole bucket and plastic bag inside and there isn't anything else written but the above.

My questions is— Is this going to be food safe?

I guess I need to ask first if lead or cadmium or anything else nasty are common constituents of a white glaze that fires at cone 6? What is the probability that this glaze is going to be safe?

Second, maybe there is the possibility that this is some well-known formulation that can be safely IDd?

Third, perhaps I could conduct some sort of test that will help me identify harmful compounds??

I would hate to waste 30 dry lbs of glaze (and I will not), and I am just a beginning ceramicist but I am making mostly mugs/teacups/teapots and wares to come in contact with food.

If you can help me troubleshoot at all I would really appreciate it!!

Thank you!!
Eric

#2 JBaymore

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Posted 31 January 2013 - 07:28 PM

Eric,

Sorry to be a bit of a bearer of bad news.

It is also possible that the glaze is not a commercial production but was made by an individual potter from some recipe he/she had. Usually if it is a commercial type product... the packaging has a LOT more info on it. (That being said, it still might be a commercial product that was re-packaged by someone else.)

Lead and cadmium CAN be in most anything. "Snow White" implies (but does not guarantee) a white glaze...... so that might rule out cadmium. (But "Snow White" eats an apple doesn't she? Could even actually be a red glaze.) But it does not rule out lead. Lead is certainly not necessary at cone 6......... but it used to be very common at cone 04. There used to be a wide-range glaze called "Tizzy" that had lead in it and was rated for cone 04 to 9...... the lead boiled out at the higher temperatures. Cone 04 to 6 is pretty abnormal a range; glazes just don't DO that. I'd instantly suspect lead in there....for the same reasons as "Tizzy".

As to the probability of it being "food safe" (please see other threads on this subject...complicated)....... probably at best 50/50.

The testing of the dry glaze powder will be costly. Any commercial industrial lab could do it. You can buy a lot of new glaze for what that will likely cost you.

You could apply it to a couple small cups and fire it to cone six and then do a commercial acetic acid leach testing for a whole series of potential leachable constituients you'd need to rule out for sure for "food safe-ness). This will rapidly cost you $100. Again... you can buy a lot of brand new dry glaze for that.

Since that powder is "unknown" chemistry... what you grabbed yourself is technically a bucket of 30 pounds of "hazardous waste". In fact you are pretty much assuming that it is correctly labeled to start with. It could be mislabeled pool chlorine or something.


As a non-pro potter you can dispose of that powder at a household hazardous waste day. I'd personally "move on" from the idea.

best,

..............john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#3 Mark C.

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Posted 31 January 2013 - 07:28 PM

after a google search there are many Snow White glazes but if its this one by spectrum you are fine.Is this a new or old bag? I think maybe its an o6 glaze as the range of 04-6 is to large.
http://www.axner.com...hite-glaze.aspx

without more info its a guess.
Mark
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www.liscomhillpottery.com

#4 blacknapkins

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Posted 31 January 2013 - 07:57 PM

Thanks to both of you guys. I'll tun a test on it and see if I like the look. If I like it, I'll use it for sculpture. I wonder if there's something I could react it with to find out if there's lead content...

edit: looks like a number of commercial lead testing products are available. Would there be any other additives I need to look out for?

etc https://www.google.c...chrome&ie=UTF-8

#5 Mark C.

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Posted 31 January 2013 - 08:18 PM

I,m with John on the move on as you really do not have enough info you know much-
I would make my own white and then you know what's in it and whites are pretty easy to make.
Mark
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www.liscomhillpottery.com

#6 blacknapkins

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Posted 31 January 2013 - 09:33 PM

I,m with John on the move on as you really do not have enough info you know much-
I would make my own white and then you know what's in it and whites are pretty easy to make.
Mark


Cads are for low-fire reds and oranges right? So it would be ridiculous to have it in a "snow white" glaze correct?

Lead is a possibility for fluxing, but I can test for it easily.

What other toxic additives are in glazes other than metals and oxides used for colourants?

#7 JBaymore

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Posted 31 January 2013 - 10:07 PM

What other toxic additives are in glazes other than metals and oxides used for colourants?


This is a highly complex subject with no absolute answers.

For example most people can deal with copper leaching out of glazes into food with only slight taste changes.... but people with Wilson's disease will have real issues. Even uncontrolled iron in the diet can be an issue for some people. In the dry powdered form, certain gum additives used for making glaze applications harder in the raw state cause some people terrible alergic reactions. Lots to this business.

(Get "Keeping Claywork Safe and Legal" by Mononna Rossol and "Artist Beware" by Dr. Michael Mcann.)

The more obvious candidates for potential leaching "issues" would include lead compounds, barium compounds, lithium compounds, and arsenic compounds. Strontium is the usual subsitiute for barium compounds... but to my knowledge it is purely an assumption that it offers less potential toxicity....haven't seen any actual studies.

I've been teaching ceramic materials chemistry at the college level for over 30 years...... and personally I'd just ditch the stuff. I wouldn't want to handle such an unknown material in the studio myself, and the time I'd have to put into figuring it out isn't worth it. Glaze materials are cheap.

How do you know that it is actually even glaze? If it is simply a white powder.... it could be a bucket of barium carbonate, EPK, alumina hydrate, lithium carbonate, white lead, G-200 feldspar or any of countless other things. Could be garden pesticides. You have no idea if that name label on the bucket is for what is in there .... or for what USED to be in there. Not everyone is careful about such things.

best,

..............john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#8 blacknapkins

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Posted 31 January 2013 - 10:10 PM


What other toxic additives are in glazes other than metals and oxides used for colourants?


This is a highly complex subject with no absolute answers.

For example most people can deal with copper leaching out of glazes into food with only slight taste changes.... but people with Wilson's disease will have real issues. Even uncontrolled iron in the diet can be an issue for some people. In the dry powdered form, certain gum additives used for making glaze applications harder in the raw state cause some people terrible alergic reactions. Lots to this business.

(Get "Keeping Claywork Safe and Legal" by Mononna Rossol and "Artist Beware" by Dr. Michael Mcann.)

The more obvious candidates for potential leaching "issues" would include lead compounds, barium compounds, lithium compounds, and arsenic compounds. Strontium is the usual subsitiute for barium compounds... but to my knowledge it is purely an assumption that it offers less potential toxicity....haven't seen any actual studies.

I've been teaching ceramic materials chemistry at the college level for over 30 years...... and personally I'd just ditch the stuff. I wouldn't want to handle such an unknown material in the studio myself, and the time I'd have to put into figuring it out isn't worth it. Glaze materials are cheap.

How do you know that it is actually even glaze? If it is simply a white powder.... it could be a bucket of barium carbonate, EPK, alumina hydrate, lithium carbonate, white lead, G-200 feldspar or any of countless other things. Could be garden pesticides. You have no idea if that name label on the bucket is for what is in there .... or for what USED to be in there. Not everyone is careful about such things.

best,

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




Good call, knocked out on round two. Conceding to pitch it.

I don't even eat vegetable oils, idk what I'm talking about risking even having this stuff in my house. ; )

Thanks guys

#9 neilestrick

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Posted 31 January 2013 - 10:23 PM

Even if this is a good glaze, a 30 pound bag will make about 7 gallons. You can make 7 gallons of white glaze for $30. So not at all worth the danger.
Neil Estrick
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