American Go E-Journal

Yunzi Stones and Lead: An Update

Friday February 14, 2014

“I bought ‘Yunzi Stones’ from Yellow Mountain Imports as a gift for my young children so we can play baduk together,” wrote EJ reader Jason Lee recently. “Later on after ordering, I saw online that this kind of stone can contain lead. So when my order arrived I got a lead test kit from the local hardware store to check them for safety. It turns out that the stones sent to me did contain lead. This is unsafe for my children to use and maybe me too. I wrote about my experience here. Thank you for the great work (the EJ does) for baduk players. I read the website every week.”

The EJ originally reported on this in 2008 (Go Review: Chinese Go Stones 2/4/2008) and we later reported (Yunzi Stones Now Lead-Free 6/23/2008 EJ) that YMI had contacted the manufacturer, who had agreed to eliminate lead from the manufacturing process of yunzi stones, which are special go pieces manufactured in the Chinese province of Yunnan. Apparently the manufacturer did not completely eliminate the lead, instead reducing it below the levels recommended by the Consumer Products Safety Commission; see below for details.

Yellow Mountain Imports responds: “Thanks for reaching out to us. We thought we had resolved this many years back when we had gone through all the reformulation and subsequent tests with the Yunnan Weiqi factory so obviously we were concerned. We take product safety seriously so when we heard these new complaints, we contacted the Yunnan Weiqi Factory immediately. They were equally concerned and arranged for a current official radio spectrometry test. The black stones tested positive at 0.005% (50 parts per million). Lead was also found in the white stones, at an even lower concentration, less than 0.002 (20 ppm). The Yunnan Weiqi Factory reformulated Yunzi stones to be within safe levels as per our request many years ago, while maintaining as much as the original qualities as possible, but it turns out that they cannot eliminate it completely. Lead makes the stones more durable and less brittle. These levels are well below the 0.009 (90 ppm) level recommended by the Consumer Products Safety Commission, but we do not claim that they are lead-free. Anyone who has purchased Yunzi stones and wants to return them can do so and should contact us.” Email with any questions or concerns.