The title is a real comment from a dear customer of us. He bought quite a few “antique/old yixings” from an online auction place. When he found us, he was puzzled “Why mine have more tea stains than yous? How can an old teapot have no stain? And how could it be possible that mine, all having beautiful patina and tea stains, are faked?“
I asked a good friend of mine in Taiwan, who is also a fervent collector of yixings, to help me answer his questions – or the questions on many people’s minds, as I don’t have convenient access to ultrasound cleaning in Houston.
He, just like me, paid quite a few “tuitions” in the road of learning yixings. He kindly did an experiment for us: he chose one early R.O.C. zhu ni xiao pin (small piece) and one “tuition” “zhu ni” teapot which he bought in Taipei’s famous Jiang-Guo Jade Market many years ago. Both have plenty of tea stains on them. And both have nice glossy surfaces.
The pictures below show the two teapots (left: genuine Early R.O.C. zhu ni, right: the “tuition” teapot) before and after ultrasound cleaning (be sure to click them to see Larger Images):

After cleaning, both were stripped off the stains. Now the result is very interesting: clearly, the genuine zhu ni still has its own beautiful almost glossy surface of glazed texture, while the other “tuition” teapot looks dull, new, lifeless.
He chose zhu ni vs. “zhu ni”, because the contrast of before-after cleaning is most obvious. Other genuine early clays will also retain most of the creaminess after ultrasound cleaning, and never degrade to that lifeless/dull conditions.
You can imagine the early zhu ni, after this cleaning, will quickly improve its surface creaminess and jewelry-grade quality after some uses/seasoning. The other faked teapot, okey, it still is a real teapot, and you paid cheap for it (hopefully!), so that’s it. But my sincere advice for such faked patina-loaded teapots: cleaning it very well, because those fakers are never shy to use whatever materials to produce those patina.
Huge amount of such faked teapots flood the antiques markets from Beijing, ShangHai, GuangZhou to Taipei, not to mention the popular online auctions sites. So now you see “tea stains does not necessary mean it is genuinely old”.
The values of genuinely early pieces are their clays (some are extinct now), craftsmanship, and of coz rarity. Stain or not stain is almost not a concern. In fact, many old stains do not contribute to the beauty of such pieces, as you can see in the above picture. Cleaning them well and carefully re-seasoning them may actually improve its aesthetics/value.
We collect good yixings, not collect stains!
Guang