Frit question

link at Seattle pottery tells if they're leadless or not, by their frit number. Their printed catalog also has the formulas for each.Fritting is to mix materials which are either soluable in glazes or toxic, heat them to a glassy state and cool them, shattering them in the cooling process, to produce the final product.I think leaded glaze frits, while perhaps safer for studio use than straight lead, would still be unacceptable for tableware (but I could be wrong here). What I recall is that just because it's fritted, you can't predict if the finished glaze is stable enough to avoid leaching out the lead.Most of the frits used today are to make Boron available in glaze without being in the soluable borate form.Brad Sondahl

> > This link at Seattle pottery tells if they're leadless or not, by their > frit number. Their printed catalog also has the formulas for each.> Fritting is to mix materials which are either soluable in glazes or > toxic, heat them to a glassy state and cool them, shattering them in the > cooling process, to produce the final product.> I think leaded glaze frits, while perhaps safer for studio use than > straight lead, would still be unacceptable for tableware (but I could be > wrong here). What I recall is that just because it's fritted, you can't > predict if the finished glaze is stable enough to avoid leaching out the > lead.> Most of the frits used today are to make Boron available in glaze > without being in the soluable borate form.> Brad Sondahl Most fritts is stable (ie the LEAD is locked away) Lead Bisilicate/sesquisilicate etc are all OK as long as you don't use COPPER oxides as colourants.... These "unlock" the fritting process and allow the lead to leach out of the pot...

Mostly this is only a real problem on the insides of "holloware" but it can be a problem on surfaces that come in contact with the mouth...

BARIUM content is an issue for stoneware as well, best to stay clear of any glaze containing more than 20% Barium Carb for food stuff... (most of the other poisonous ones are gas long before then)

Mind you my dad used to have a pewter mug fer 'is beer that was 150 years old (90% lead 10% zinc (i think)) and he lived to his 80's... Hugs Eddie

Others have already answered. But the way you phrased your question make me think you're asking if using, say a fritted flux and lead together would make the lead insoluable and safe. No. The material has to be fritted first to be safer. As someone else wondered, I don't know how safe fritting can make various materials.

Elaine

Thanks, guys. I think I understand. Basically, to be safe, stay away from lead and barium if it comes into contact with food, drink or the mouth -- regardless whether frit was used?