Wednesday, September 28, 2011

Dear Cupcakes...

Berkeley Republican students yesterday sold cupcakes priced according to the buyers' ethnic identity and gender. "White cupcakes" very expensive; "others" very inexpensive.

It was meant to highlight what the Republican students see as inequalities in proposed admissions legislation that would allow the UC's to take a person's ethnicity and gender into account for purposes of admission--an important public issue that deserves intelligent debate.

Therefore, I'd like to know how much the students involved are paying for their education.   For men and women benefiting from one of the highest quality educations in the nation, and the world, the analogy they made was remarkably unsophisticated, brute, and empty of real content.

I don't think their parents are getting their money's worth.

Friday, September 9, 2011

Long Term Considerations in Ceramic: COE

I've seen more and more people putting crushed soda lime and other glass on ceramic. I've been hesitant to do so. My reasons follow.

Ceramic glazes are also "glass on ceramic." They are carefully calculated, so that they expand and contract at the same rate as the ceramic on which they are used. This is to make sure that they adhere to the clay surface over the life of the object, and don't come off. Glass can expand and contract with changes in the weather & the immediate environment (such as a warm body, pool, shower, jacuzzi, winter).

The COE (coefficient of expansion) of soda lime glass (bottle glass) is 9. The average COE of common commercial high fire clays is in the neighborhood of 7. Porcelain drops down around 4. Both bottle glass and ceramic will expand and contract over their lifetimes--but at very different rates when the COE's are disparate.

A somewhat poorly matched glaze will craze--the "crackle" effect. However, increases in mismatching between glaze and ceramic can actually result in the glaze coming off of the ceramic. This may not happen immediately; it can occur up to several years after firing, when the two materials have gone through numerous cycles of mismatched expansion and contraction. This knowledge makes me reluctant to risk using commercial glass as a glaze on ceramic pieces.