Hicham:I have a pair of Camphor bowls from Kurokigoishi. But after two years they lost a bit of their lustre. What is the best method to make look like new again?
Bob McGuigan: I don't know the answer to your question but why not contact Mr. Kuroki (by email) and ask him. From what I've read elsewhewre he is responsive to questions like this.
I just send him a mail. I'll post his anwer here for futher reference.
Answer from Kurokigoishi: "To shine gosu or regain luster, please clean it carefully with dry cotton cloth, but I don't think it will look like totally new. Gosu craftsman knows how to make it with special technique but it requires a special skill and it is impossible that amateur people to do it.
With respect to white clamshell stones, please clean it carefully with dry cotton cloth one by one, too. But again I don't think it will look new. Go stone craftsman knows how to do it, but again it needs a special skill and amateur people cannot do it."
Not the answer I was hoping for ofcourse. If anyone has an idea what the professinals do to the bowls or to the white stones, let me know. Or what product I could use to just make it shine, if I can not make them look new again.
from Kuroki-san's response, it is my guess that the gosu craftsmen buff the bowls at high speed. This would be one explanation why no product was offered to return the bowls to their original state. It would seem likely that the dulling of the finish is caused by miniscule scratches in the surface.
Bob McGuigan: You haven't said how much wear your bowls have. If they are scratched through the finish to bare wood than it might be hard to restore them. If they are just a little dirty and scuffed maybe some standard furniture polish might work. I guess the worry might be that it would change the color or appearance. If you want to take this route try out whatever wax or polish you are using on an inconspicuous part of the bowl, say the bottom.
Bob McGuigan: Museum conservators use microcrystalline wax to preserve wooden items. Here is a web page about it. It sounds like it might be good for go bowls or boards. Try it on an inconspicuous place first, though. http://www.woodfinishsupply.com/RenWax.html