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When a manufacturer states that a specific line of glazes is 100% mixable, and that each of these glazes is food safe on its own, can I assume that means that if I layer or mix colors in the same line the glaze is still food safe?  Applied and fired according to their instructions of course.

 

I'm really agonizing over glaze safety and no, I don't want to make my own glaze.  The prevailing wisdom, and what the manufacturer's say,  seems to be that once different food safe glazes come in contact with eachother, all bets are off as to the food safety of that glaze.  This makes sense to me, but I'm seeing all sorts of combining going on in utilitarian ware.  Beautiful combining.  I don't think everyone is sending their stuff off to the lab for testing.  Or maybe I'm wrong. At this point I'm using single glazes anywhere food touches.

 

I'd appreciate any guidance and suggestions.

 

Thanks

 

Irene, trying hard not to contaminate anyone or make any enemies

 

 

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For sure it means they can be mixed without any ill effects like bubbling or pinholing.I would assume they mean food safety, too, although I would confirm that with the manufacturer to be safe. I would imagine that they are all the same base formula or at least very similar, so if the concentration of colorants is within safe limits in the individual glazes, then mixing them will most likely still be safe.

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I would think that with the trending of layered glazes, especially at cone 6, that many manufacturers are trying to establish a line of glazes that allow layering with no ill effects. In the past, I remember problems with glazes over glazes when working with glazes within a manufacturer, and when working with glazes from a variety of manufacturers. In the long run, it was a matter of test tiles, and trial and error. Much of this came from the students trying something new, not following the warnings or the evidence as presented in test tiles.

 

 

best,

Pres

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Amaco has a symbol for "mixable". From their "celadon" line. Looks like clear pooling glazes with stains. A couple other lines from them say they are mixable also. Does look like they have the same bases with colourants/opacifiers added.

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Email the manufacturer for clarification but it sounds like you can combine it with other glazes that they make. 

 

 

I am making my own glaze from a natural source and I am using a lab to insure there are no hazardous heavy metals or anything else to worry about. Its not cheap but I'll have peace of mind. It looks like you have quite a few labs like this in New Jersey. You will be looking for a geochemical testing lab. Ask for ICP analysis of the sample material and tell them what you are concerned about- i.e. contaminants that may be able to be leached out of a silicate glaze. The products you are looking at likely had to go through this procedure in order to be labeled as non-toxic so this may be all redundant and overkill - kind of like going over the food & drug administrations work on one of their approvals! Its really meant for checking DIY made natural source glaze and clay- you should be able to trust the product details as Min described above especially if its a major manufacturer that is trying to protect itself from legal action.  https://en.wikipedia.org/wiki/Inductively_coupled_plasma_mass_spectrometry

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Email the manufacturer for clarification but it sounds like you can combine it with other glazes that they make. 

 

 

 you should be able to trust the product details as Min described above especially if its a major manufacturer that is trying to protect itself from legal action.  https://en.wikipedia.org/wiki/Inductively_coupled_plasma_mass_spectrometry

 

Except they always have a CYA line like "Tableware producers must test all finished ware to establish dinnerware status, due to possible variations in firing temperature and contamination.

terrim8 likes this

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 Min, it is the Amaco Celadons I was talking about in my post.  

 

What I've decided is that unless the glazes are 100% mixable, like the Celadons, I'm going to continue to use only single glazes on food surfaces.  The outsides can be a free for all but the insides will be pristine!    I hope you're right Pres, and manufacturers are working on other lines that are mixable.  

 

Thanks everyone, for giving me a place to talk about this out loud.  

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So terri8m,  I did email  Amaco,  (thanks for the suggestion),   and they responded that the Celadon line colors are all compatible for mixing with each other, and retain their food safe rating when mixed.  The Satin Matte line is the same, except for the Orange and Red, which have different bases and so can't be mixed with any of the other colors in the line.  

 

It's nice sometimes when the answer is either black or white.  Unless it's orange or red......   

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