09-30-2015, 03:46 AM
here's a link to the tutorial
01-22-2016, 11:43 AM
Hello, I'm new to this forum and I work with glass, but about 40 years ago I did some work in iron foundries and so, being a pyromaniac, like to play in the arts of the fire. Anyway, I used to make stoppers and collars for glass furnaces - "D" shaped tiles 12" x 10" x 1.5" expendable shapes for sealing furnace mouths. Also gathering rings,that float on the surface of the glass. These things had to withstand some thermal shock, alkali batch dust, some slagging due to glass contact, and long periods at 1400 degrees Centigrade. The mix I used was 2 parts fireclay and 1 part Firebrick grog 1/8th" to dust. Mix with water and leave until stiff and pliable. Ram into wooden moulds lined with wet cloth, tip onto a board or concrete floor to dry. Once dry, warm at furnace and they are ready to use. The mix can be used for making your own custom designed blocks, bricks, burner ports, furnace lids, etc. Good for patching furnaces, or when building furnaces, as a gap filler, especially to stop flame ingress. It will shrink a bit, but if you don't need the plasticity, add more grog and it will shrink less. This is a hot face mix. It could easily be used for lining a crucible furnace or the like. In the foundries they used something similar called ganister - a silica rich clay, for patching up cupolas, lining metal receivers, bogies, ladles etc.
Now I also have a question. I'm building a kiln and a small crucible furnace, using vermiculite with sodium silicate/CO2 binder as back-up insulation shapes. Can anybody advise on the proportion of Sodium Silicate/ Vermiculite?
Bob the Slob
01-22-2016, 12:59 PM
vermiculite is really bad around foundry stuff, what you want is perlite. vermiculite is designed to hold moisture in the soil, so all it'll be is just a sponge for water/moisture in your lining, so it'll just pop and destroy the lining. perlite doesnt absorb the moisture, it's just there to airrate the soil and let more air get through it, which also makes it very good for refractory uses.
I think ckindred on youtube had a setup like what your wanting, but they added a small amount of sandblasting grit/alumina to the mix too, here's the video
I dont know how well that mix works, but it seems to be the closest to what your after.
01-22-2016, 10:41 PM
Vermiculite/Perlite with Sodium Silicate Binder
Thanks for the info. ckindred (youtube video) used 4litres Perlite plus 350 ml Sodium Silicate and 350 ml water with some Alumina powder for his forge lining. (We use a similar gas fired "Glory Hole" for reheating when glassmaking -Drum lined with ceramic fibre).
Anyway, I'm going to try a fireclay/grog shell about 1" thick. 1400 deg C ceramic fibre behind that and the vermiculite - or perlite and Sodium Silicate mix to fill the rest and gas it with CO2.
If that works I'll try making slabs of the stuff for kiln walls. Its only going up to 700 deg C.
Bob the Slob