Not just electronics in fact. Afaik, it applies to every lead-based material. Maybe i'm wrong about that, I didn't check. Still doesn't change my point though, unless you eat the stones, it should do you no harm

The RoHS directive took effect on 1 July 2006, and is required to be enforced and become law in each member state. This directive restricts (with exceptions) the use of six hazardous materials in the manufacture of various types of electronic and electrical equipment.

The thing is, touching the stones and then touching your lips, or eating while playing, or... can actually be a moderate risk. With long exposure, a relative risk, after all, lead does not go away, it just accumulates on human bodies.

I seriously doubt it.

Exposure to lead and lead chemicals can occur through inhalation, ingestion and dermal contact.

I wouldn't be worried by lead in glass Go stones.

Lead in paint [..] to some extent soluble. But glass is not soluble [..] So if a child swallows a glass Go stone [..]

Glass Go stones certainly don’t contain lead.

Yunzi is NOT glass, it is a ceramic, it is mostly stone powder that has been sintered, i.e. pressed and baked together with great heat, and thus it is porous.

They used to (and some perhaps still do) add lead powder for weight, and this lead can be abrased from the porous surface with skin contact. Also, it has happened that yunzi stones break, and, according to those who wrote about it, some of their broken stones contained a white-ish, powdery substance. I assume this can happen when for example the sintering was incomplete and the stones have not been “baked” long enough or with too little heat.


Greetings, Tom

[..]

its not added for weight. Its added to lower the melting point for the glass (or ceramic, which is a form of glass), to make the molten glass easier to work with.

viewtopic.php?p=90688#p90688

and the powdery substance inside broken stones is just the "stone" mixture itself from improper cooling.

Before I only knew that glass is amorphous and made from molten silica, plainly said: molten sand (plus some additions for lowering the melting point), and that ceramics are baken (burnt? kilned? It began with clay), and that they are not molten as much as glass, or better perhaps to say that they are not as liquid/fluid/ as molten glass is. And that Yunzi is a sintered ceramic made from stone meal (with a süper sikrit recipe), under pressure and heat, thus the porosity. I have a set of Yunzi with a green-ish luster which are said to be made with a certain amount of powdered green Jade.

[..]

looks pretty molten/liquid/fluid to me...
[youtube]https://www.youtube.com/watch?v=rPdk6PbFbZk[/youtube]

(just the video number, not the whole URL, then it works)

What still remains is that Yunzi is somewhat porous,

Wow, that was not obvious. Thanks.


I don't have any to test, but I have my doubts here too.

According to the Wikipedia article posted in the other thread (and a few other links in a quick Google search for lead leaching), one could probably soak their stones in whisky for a while to leach most of the lead off the surface of the stones (assuming they are not porous). Just don't drink the whisky afterwards.

And while the lead content is already far below Health and Safety regulations, then it will be even less (for the truly paranoid).

And while the lead content is already far below Health and Safety regulations....

To be honest, I don't understand the discussions.

with Yunzee stones