Lead and teaware...Is this safe?

[JBaymore]

Thanks... didn't know that.

We are screwing up this planet pretty fast, aren't we?

best,

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

[gingkoseto]

Good to know - both about kutani containing lead and about in-glaze paint being safe.

Only Kutani (et al) that has overglaze enamels contains lead... and it is only in the composition of the overglaze itself. The high fire glazes on the porcelain that are the ground onto which overglaze is painted and fired onto do not contain lead compounds. As I mentioned elsewhere on this board, the green overglaze is more of a problem with lead release than the red or other colors.

And please don't extrapolate the concept into ".....in-glaze paint being safe". It depends a lot on what ceramic material is being painted "in-glaze", and how that material affects the chemistry of the area of glaze it "stains". Use of materials like pure or almost pure oxides as a painting medium under or over a powdered glaze layer can sometimes supersaturate the glaze in that area with colorant that the cooling melted glaze layer cannot hold in solution.

If that colorant has toxic properties, then it is possible that painted area of the piece will tend to leach that material. If you are painting with iron oxide....... well..... most people can use a bit more iron in their diet . But if you are using a non-encapsulated cadmium bearing stain, then you certainly will possibly have "issues".

Then about the paint with lead on the outside - will it cause danger by skin contact?

Good question. At a very, VERY "technicallity level" (meaning so small an issue as to likely be of no worry at all), there can/will form a minute film of white lead oxide on the surface of the lead based glaze as some of the lead which is loosely bonded into the glass matrix oxidizes from contact with the oxygen in the air. This is similar to what happens with the surface of lead paint, but the paint holds the lead far less tightly bonded than the glaze does.

Oh! Just thought of this - is the red mosquito on my avatar the lead-containing red paint?

Ginko, Can't tell from the photo precisely, but likely that is the case.

There are limited ways to produce a blood red in ceramics. One is finely ground iron and lead oxide at low temperatures. Another is a precidely formulated and reduced copper bearing glaze at high temperatures. The third (which is more "pink-ish") is a combination of chromium oxide with the exact right molecular ratio of tin oxide. And the last is a coloring stain composed of cadmium sulfide and selenium oxide.

That form of Cd stain is also availabe in what is called an "encapsulated" format. What that means is that the little, already stabilized, red particles are surrounded in a little "bubble" of zirconium glass. This prevents the cadmium compounds from leaching out of the bubble. Expensive!!!

best,

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

Wow! Thank you John for all the information! It's really good to know!

[gingkoseto]

our food is covered in pesticides and often has toxic chemicals added for various reasons like colour and to increase shelf life....I don´t think a trace of lead on the outside of our cups matters...

heck I ate tuna subway yesterday....that probably has more lead in it xD

Yeah that's true! Probably we are all more toxic-tolerant than ancient people

And the tuna and other predator fishes, that's a typical case, among many others, mentioned in Marion Nestle's book What To Eat - examples of things that FDA is supposed to post stronger safety warning to consumers, but of course there are political and monetary factors that prevent them from doing that.

[teaisme]

I love tuna

We are screwing up this planet pretty fast, aren't we?

I hear you man, but at least some things are finally moving forward. Just recently the President’s Cancer Panel put out a report promoting organics and some common sense about the use/testing of chemicals. It's about time.
Maybe in 20-30 years people won't have to be so paranoid about the basic everyday things.