I already mentioned an interesting book with a very important chapter. The authors G. Scarinci, G.Brusatin and E.Bernardo made a nice work about the history of glass foams with the focus on glass recycling.

• Different techniques are mentioned but the powder process is today the favorite method.
• They make reference to a number of patents and are describing the currently employed methods.
• A list of different starting glasses are given with emphasis on recycled glass
• The particle size of powder and foaming agent are discussed in relation to the cell structure but unrealistic thermal conductivities are given.
• Foaming temperatures and time are given with carbon black as foaming agent
• The cooling rate is discussed without taken into account the thickness, which is not logic.
• Different foaming agents are discussed based on thermal decomposition and by reaction. Even SO2 is mentioned as foaming gas.
• The different glass foam products are listed: gravel, blocks and pellets with their properties.
• Alternative processes are discussed with a chapter about foaming CRT-tubes.
• Last but not least, an impressive list of references is present with many interesting patents.

This review article is a fantastic introduction for people interested how glass foaming improves ecology.