Last Updated: Jul 19, 2016     Views: 113

Thank you very much for your question. I suggest you read the chapter on "Annealing and Compatibility" in: 

Bray, Charles. Ceramics and Glass: A Basic Technology. Sheffield, England: Society of Glass Technology, 2000, pp.146-152. 

"If pieces of glass [or glass and ceramics] of different expansion are fused together it is inevitable that some strain will be created when expansion or shrinkage occurs. If the coefficients are close then the glass may be able to withstand this strain but more often than not, cracking or breakage will develop." Bray also describes other reasons for difficulties with annealing and discusses lead glasses that have a high coefficient of expansion. Cast glass is more difficult to anneal than blown glass, but Bray has some general suggestions. 

In his book, Techniques of Kiln Formed Glass, Keith Cummings publishes a variety of annealing schedules for cast glass based on the thickness of the glass, the annealing point of specific glass, and the strain point of specific glass. [London: A & C Black; Philadelphia: University of Pennsylvania Press, 1997] The supplier of your batch or cullet (if you are using a standard mix) can provide annealing schedules as well as the annealing point and strain point. 

Another excellent discussion is Dr. Frank Wooley's chapter on "Annealing Cast Glass," in Lucartha Kohler's book Glass: An Artist's Medium (Iola, WI: Krause Pubilcations, 1998, pp. 212-217). He includes a chart for "Annealing Schedules for Casting Glasses 
(Conservative Schedules for All Soda-Lime and Lead Glasses)" p. 217. 

If you wish to obtain copies of any of these items, please contact your local library. The Rakow Research Library is a member of OCLC; your library can contact us through OCLC or they may mail an Interlibrary Loan form to us. You may request up to five items at a time. We send photocopies of articles and microfiche copies of our books (if they have been microfilmed) through Interlibrary Loan for four weeks use. 

The books are also in-print and available from book dealers. 

I am also sending our bibliographies for annealing glass and coefficient of expansion. 

I hope this helps and thank you again for your question. 


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