Moreover, different kinds of clay will differ in elasticity. Even purple clay has been used in limited fashion to render rectilinear designs, but this type of clay has a shrinkage rate of 6 %. As the metallic content decreases, the shrinkage rate can rise to 15 %. "This means that sometimes a teapot and its lid are wildly mismatched in terms of size," he says.
再說，不同土質有不同收縮率，中國紫砂壺雖也有少數方型設計，但用的是含鐵量高的陶土，收縮率為 6 %，而瓷土含鐵量少，收縮率高達 15 %，「燒出來壺蓋與壺底的天、地比例都不一樣，」他說。