Enamelling explained here:
http://en.wikipedia.org/wiki/Vitreous_enamel

Crystallization in another context in relation to enamelling:

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T...

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Note added at 53 mins (2009-03-12 11:31:36 GMT)
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The crystallisation of a glass-ceramic enamel system in which two modes of crystallisation are observed is described in some detail. During the coating fusion, uncontrolled, spontaneous devitrification of kalsilite occurs throughout the glass. In a post heat treatment process a controlled, intentionally nucleated crystallisation of the matrix occurs. The preferential diffusion of iron from the substrate, through the glassy phase of the biphasal system during fusion is observed. The implication of this behaviour on adherence is noted.
http://www.springerlink.com/content/m062744m5031348g/

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Note added at 59 mins (2009-03-12 11:37:10 GMT)
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This invention is concerned with the preparation of thermally crystallizable enamels suitable for application to glass-ceramics, particularly glass-ceramics having coefficients of thermal expansion less than 15×10-7 /°C. The enamels are capable of being fired to maturity simultaneously with the precursor glass body being crystallized to a glass-ceramic.
http://www.freepatentsonline.com/4532221.html

I think maybe that 'enamelling by crystallization' would be better. I am not sure it is a specific technique though obviously unusual in enamelling techniques, which is presumably why it is mentioned specifically in this way.

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Note added at 4 days (2009-03-17 09:14:15 GMT) Post-grading
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Thanks again for the points, Mary-Ann