I had breakfast with a Canadian Ham radio friend today who said that they used to ocassionally burn broken glasses in their coal stoves to "glassify" the chimney. He said the coal gets so hot that the glass will MELT and deposit on the chimney sides, sealing the cement between the tiles. Anyone hear of that ? Pro's/con's?
Just some speculation on my part and assuming there is glass particles in the gases.... The particles would cool well below any level they would need to adhere to the sides of the chimney plus you will already have dust and dirt particles on the sides of the chimney that will prevent adhesion.
You can certainly melt it with a coal fire though, at least to the point where it s pliable. We used to do this frequently with bottles in a wood fire. The idea was to try and make an ash tray but the bottle would usually break during the process and those that did survive were usually very brittle.