Originally Posted by
kaliayev
But a big drawback is that they hide severe damage very well
Do what the QC guy at Kohler does. After every porcelain toilet bowl and sink comes out of the firing oven, a guy with a large steel ball, about 2 inches in diameter, taps each product in several places. If teh ring is clear, the product is good. If the ring is deadened, there is a crack and the product is rejected.