There are any number of souls that have the idea that the reason the glass in old colonial homes as well as in old stained glass windows is thicker at the bottom is because that glass having been described as a “super cooled liquid” is still actually flowing. The idea that glass is actually “flowing” is an urban legend! This paper by Dr. Robert Brill of the CMoG should help clarify this oft held belief.
This page contains downloadable pdf files that may be of interest to you. Just click on the pdf icon to the left of the info and you will receive a file with the information
This is one page from Glass Notes and it depicts two views of building the Skamol Annealer. There is a complete set of drawings in the book that I believe are easy to follow. For those of you that do not know, Skamol is material that is not carcinogenic like fiber insulation and has excellent insulating qualities. It is rigid and easily cut and routed. It is very popular these days for ease of use and the health benefits it offers over fiber.
I receive a good number of phone calls asking if I know what the skin temperature of an annealer is if given the internal oven temperature. This chart supplied by the Skamol Co. gives the skin temperature for an oven with an internal temperature of 1700° F. with a wall thickness of 2 inches of Skamol V1100 (600) slabs and a back-up of 2 inches Super 1100E calcium silicate slabs. Page 2 gives the results in an easy to read diagram. I used 1700° F as an extreme temperature. If you build one of these beauties and you have a lower internal temperature you will have a cooler skin temperature.
This is the formula that was in the 3rd edition of Glass Notes but was not included in the 4th. It was rarely used and the materials were very hard to find. I have been told there is a small interest in it so I’m posting it here with a caveat: Use at your own risk. The materials found in this formula can cause sever burns. It must be used in a well ventilated area and you should wear a protective face mask. The formula can only polish lead based glass but will give a frosted sheen to soda/lime glass. Don't call me and ask where to get the chemicals. I have no idea.
Every once in awhile I receive an inquiry on the feasibility of using pop and beer bottle cullet in the small studio. I usually send two pdf documents, one prepared in 1997 by Norm Courtney, for the CWC (Clean Washington Center) located in Seattle WA, and the next report on beer/pop bottles. Norm’s final report was titled, Post-Consumer Container Glass, Remelting Process Assessment. It was very thorough and included, among other things the processes incorporated by three small studios in the use of post-consumer recycled glass products in their glass melts. The report outlined the chemical additions needed to make the bottle cullet workable. Norm's conclusion at the end of his report stated: “Depending on the application, the use of recycled glass (cullet) can also dramatically reduce energy and raw material costs.” This is an excellent document for any studio interested in using bottle cullet.
This report is based on the late great Norm Courtney. His research concluded with the benefits and drawbacks of using pop bottle cullet. Before going and clearing the beer bottles off the tables at your local bar to melt in your furnace it should be noted that there are some caveats involved with the melting of post-consumer cullet. It should also be noted that the reports are over ten years old and although the costs of materials outlined have changed a good deal the processes outlined remain pretty much the same.
If you have an interest in the use of post-consumer glass in your glass process then these reports should be a great help.