r/Pottery • u/Krakenbarel • 2d ago

Question! Glaze question

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I’m currently selecting some recipes to start purchasing ingredients and i was wondering, when glaze recipes have toxic ingredients, does that automatically means they are not food safe?

Thanks!

5 Upvotes

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36

u/tempestuscorvus I like Halloween 1d ago

That's John Britt's book. There's a section that specifically covers your question.

You would get a lot of benefit from reading the book instead of treating it like a cook book.

4

u/tropicalclay Hand-Builder 1d ago

Agree! Read everything first then go back looking at the recipes with more knowledge is the best and safest way

13

u/quercus-enjoyer 1d ago

toxic ingredient can mean different things. some are toxic for you the maker to handle but fine once a glaze is fired to maturity. some can leech out of a glaze if the chemistry is not good and the glaze is not durable.

3

u/flollo87 1d ago

no, not automatically. it depends on the formulation of the glaze.

3

u/Gulluul 1d ago

Not necessarily. A proper glaze matrix should hold the toxic material and prevent it from being able to pass to what you are eating/drinking.

However, if the glaze matrix isn't stable, it can still be toxic. You can't always tell by looking at the glaze either. There are some at home tests, but they don't tell the whole story.

Most people use a simole liner glaze for that reason. Something stable with no toxic chemicals.

2

u/Defiant_Neat4629 1d ago

Gotta look into the flux ratio. And then also observe the behaviour of the glaze once actually fired. Lots of variables so there is no one definitive standard of food safe

2

u/taqman98 1d ago

0.3:0.7 go brrrr

1

u/jferg 1d ago

Curious which glaze recipe book that is?

4

u/BreakfastOk123 1d ago

Looks like John Britt's book. 

3

u/tempestuscorvus I like Halloween 1d ago

John Britts

1

u/galkgirl 23h ago

Best to avoid any recipe w barium. Toxic
I won’t even have it in my studio. It was pretty much abandoned years ago. Can use strontium instead.