Sticky/Tacky Residue on New Yunzi Stones

[Synergist969]

To whom it may concern/those willing to assist...:

I am new to the game of Go, but purchased several items from Yellow Mountain Imports, including a goban and Yunzi stones for my nephews, as well as a different set of both for myself. The Yunzi stones that I purchased for my nephews were just as stated/expected...lightly coated with a fine white powder, which washed off without any problems.
Along with a floor standing goban, I purchased a NEW set of size 41 Yunzi stones for myself from Yellow Mountain Imports. They arrived in plastic bags, within the bowls I had ordered.
HOWEVER, the surface of these stones are coated with a somewhat sticky/tacky, rubbery(?), hydrophobic clear residue, not totally unlike a soft wax, or gummy aging/oxidizing vegetable oil. I do not know what this residue is, and if it is expected that it should dry as a protective coating, or should be washed off. I did attempt to wash off one white stone, beginning with just tap water, then with a common dish detergent, resulting in some cleaning of the residue, perhaps as much from the drying it with a paper-towel as the dish detergent. I have repeatedly requested instructions from Janie at Y.M.I., and received only one responce, addressing WHITE POWDER removal from new stones. So...:
(1) What is the composition of this residue?
(2) What is its purpose, (if any)?
(3) If it requires removal from the stones, what do I use to remove it without harming the Yunzi stones?
(4) Any other instructions as needed for the prolonged enjoyment of this equipment? (Yes, I did receive the minimal pamphlet which arrived with the stones).

Thank you for your help in advance.

Sincerely,
T.A.Kogstrom

[xed_over]

They're just glass stones. Wash them.

[Bonobo]

(Sorry, no help from me :-S)

They're just glass stones. Wash them.

Synergist wrote “hydrophobic” and “sticky”. Even detergent resulted only in “some cleaning”. Methinks it would need some solvent, alcohol perhaps. Don’t know whether that’s good for the material.

And no, Yunzi is NOT »just glass stones«, cf. http://en.wikipedia.org/wiki/Sintering# ... _sintering

Greetings, Tom

[lemmata]

WHITE POWDER

Short story: It may be lead. Buy a home test for surface lead.

Long story:

Yunzi stones might have lead content; it may oxidize and appear as white powder. YMI had a recall of Yunzi stones due to surface lead content. They claim that they were able to track down the source of the contamination and that the new manufacturing process does not introduce lead. They offered free exchanges of old Yunzi stones (with lead) for their new Yunzi stones (presumably without lead).

I purchased a set of Yunzi stones from YMI a couple years ago. Following a blog post by someone (Chiyo dad? something like that) I read, I purchased a home test for surface lead and tried it on my stones. The test was performed after a year of usage and several washes. The stones tested positive for surface lead. I contacted YMI, and they offered to send me replacement stones. Unfortunately, they claimed that there was an e-mail server problem, which made them fall behind on their orders and prevented them from making good on the promise in a timely manner. I was told that they would get to my request, but it's been more than a year now and there has been no communication. Of course, this is 99% their fault (1% my fault because I have been too busy with life to remind them...this reminded me so I will write them again today).

YMI seems to be run by good people (given how easily they agreed to replace my stones), but they might not be the most organized.

Anyhow, I would buy from YMI again (after they replace my stones), but I would not buy Yunzi stones from anyone because I am paranoid about lead.

[zslane]

I would be very surprised if it was lead. They stopped making yunzi stones with lead many years ago. I bought a set of size 41 yunzi stones from YMI a few weeks ago and they did not have any residue covering them. You might want to contact YMI and arrange for an exchange.

[pwaldron]

I can't offer information on why it's there, but if you are looking to remove it I would try various solvents in this order

• Isopropyl Alcohol (IPA)
• Acetone (nail polish remover)
• Gasoline
• NMP, can be found in car engine cleaners

All of this should be done out of doors, with a basket or something that will keep the solvents away from your skin. Use IPA, then water to rinse clean.

[Bonobo]

[..]

All of this should be done out of doors, with a basket or something that will keep the solvents away from your skin. Use IPA, then water to rinse clean.

… and don’t smoke while doing it

Also, I’d let the stones dry very thoroughly before rinsing with water b/c Yunzi seems to be somewhat porous and thus may keep some of the solvent inside.

It’s also said to be a good idea to use some mineral oil on the stones (explained elsewhere in L19) but this would be after the cleaning.

[bogiesan]

Weird that the boys form YMT are not responding quickly and thoroughy. Call them instead of using email?

Whatever yunzi is, it's been through a kiln at several hundred degrees. I doubt there's much you can do them with household chemicals that will affect the surface properties negatively. Put two of each color through the dishwasher maybe.

but please keep us posted. Photos would also be appreciated.

[Synergist969]

Dear ALL:

Thank you for your individual/collective input...somewhere within there there IS a good solution to my dilema. Incidentally, the one e-mail response I DID receive from Janie at Yellow Mountain Imports provided my a link to the standard way that one washes off the while powder with water, dry them and then oil them...possibly suggesting that MY particular situation, (the sticky residue), was not even read or understood, such that Janie simply provided a pat answer to new stones...

I am not sure who is responsible for reading and really addressing purchasers' questions/issues, but if I had the telephone number for Yellow Mountain Imports, I would really love to ask them to provide to me answers to my questions, as I HAVE asked ALL of the essential questions to them that I have asked on this forum...

Thank you.

Peace/Namaste,
T.A. Kogstrom

[palapiku]

Just throw solvents at them until something works. Then wash off.
Yunzi is basically crystal glass fortified with rock, you're not going to damage them with chemicals.