Wednesday, January 02, 2008

Lead check for Yunzi stones

A Lead Check kit from Home Depot for about $6.

I was recently alerted by a reader about the surface-accessible lead content (chemical symbol = Pb) of his Yunzi stones that he had purchased in October of 2007 from Yellow Mountain Imports. All the hullabaloo about lead in children's toys from China piqued his curiousity so he initially tested his stones with a kit similar to the one pictured above. The test came out positive.

The old recipe for Yunzi included lead oxide which helped reduce the brittleness of the white stones but current formulas are no longer supposed to use this.

My reader had access to x-ray fluorescence testing to confirm the kit results. The white stones contain almost 200 times the amount of lead allowed by US law in paint, and the black stones about 5 times.

My Own Test

I picked-up a Lead Check kit from the local Home Depot to do my own test. As some of you might recall, I had purchased my set in late 2005.

Sadly, the results were positive and showed that my stones did have surface-accessible lead.

Here's a close-up of the test-swab which turned pinkish-red after being rubbed on a white Yunzi stone for less than thirty seconds.

Educating yourself on the risks of lead

The risks from dermal contact (through the skin) are low. Children under the age of six are the most vulnerable to lead exposure because their bodies and nervous systems are still developing rapidly and because they are most likely to place objects in their mouths (thus maximizing exposure).

To better understand the risks and concerns of lead, please see the following links:

YMI responds to take care of its customers

The reader and I had corresponded with YMI regarding these findings. YMI was caught off-guard as they had received assurances from the Yunnan Weiqi Company (YWC) that their shipments of Yunzi were lead-free. The images below are from documentation provided in 2006 certifying that the stones had no lead content.

Certification from the Yunnan Weiqi Factory showing zero lead content.

Test results from the Yunnan Weiqi Factory

YMI conducted its own tests and found surface-accessible lead on samples of their Yunzi.

YMI brought this matter up with the Yunnan Weiqi Company. The YWC received two new official lab results of the most recently produced Yunzi, confirming 0.19% lead in the white stones and 0% in the black. They were rather baffled because they had taken lead out of the formulation in early 2006. The lead had occurred somewhere in their supply chain and they eventually narrowed it down to their zinc supplier. The zinc supplied for use in the Yunzi contained lead. The YWC will be switching zinc suppliers and will also try making Yunzi without zinc.

In the meantime, YMI is working to put together an exchange program for their customers who have concerns about surface-accessible lead. Obviously, because the YWC is still sorting-out its sourcing, it may take as long as a month before YMI has lead-free Yunzi available. Pong Yen at YMI has advised that if anybody is immediately concerned and does not want to wait until then, they can send in their set of Yunzi stones (without their bowls) and YMI will send them a set of marble stones as a replacement.

A complete set of stones and shipping address should be sent to:

Yellow Mountain Imports
Yunzi for Marble Exchange
227 S. Raymond Ave.
Alhambra, CA 91801

You can also contact them via their website.

ADDENDUM (Jan 3, 2008):
Yunzi stones from the Yunnan Weiqi Company are sold all around the world by many vendors. If you did not acquire your stones from Yellow Mountain Imports and have concerns about the stones' lead content, please contact the vendor who sold you your set. Regretfully, other vendors may have their own policies with regards to safety-issue exchanges.

A discussion on this matter is also active on Click here to go directly to that topic.


At 8:13 AM, January 02, 2008, Blogger Oolong4Go said...

did you test the Jade luster stones you reviewed in your last blog post? and if so did they contain lead also?

Thanks Eric

ps > I am not very concerned about the lead in go stones as I don't allow people to put them in there mouth and this is just more incentive to not allow eating while playing go with my set.

but this is very important info for anyone with small children at home.

At 9:10 AM, January 02, 2008, Blogger You Haven't Heard of Him said...

Excellent find! Who would have known? Thank you for the post. I will link you in my Go blog.

At 12:08 PM, January 03, 2008, Blogger ChiyoDad said...

Thanks Eric and ramatheson. The Jade luster stones are with another family member so I haven't been able to test those. I may not be able to get to them until later next month. I suspect however that those may test negative.

At 4:53 PM, January 03, 2008, Anonymous Anonymous said...

This may not be a big problem for personal sets, but I expect that Go clubs may have some issues here (especially those with beginning Go programs for children...)

At 7:14 PM, January 03, 2008, Blogger Zac said...

Hey, that's actually pretty interesting, and a ripe time for a new post! I'm glad to see how well YMI is handling this (I actually bought a set of Yunzis from them in November), even though I'm not personally concerned with the lead. Hope your daughter never tasted your set!

At 12:29 PM, January 04, 2008, Anonymous Anonymous said...

One more reason to go straight for the KGT slate an shell stones!

At 12:39 PM, January 08, 2008, Blogger frankiii said...

Thank you, ChiyoDad. I've just begun playing with my kids on the YMI board and yunzi.

I'll be sending them back soon.

At 7:36 PM, January 09, 2008, Blogger DC said...

Hey guys, I have a set of the Jade luster stones and I'm trying to get to the store tomorrow and pick up one of those tests, more out of curiosity than anything else, but if I can get one I'll let you guys know how it turns out.

At 5:45 PM, January 11, 2008, Blogger DC said...

Sorry guys, couldn't make it to the store but it sounds like the tests from the company will be out soon anyway.


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