Castable refractory - any experiences with Ciment Fondu?

Thanks. jaCK - I have builder's buckets and the SDS mixing paddle, can't be worse than than mixing about half a ton of lime mortar to point the walls I guess!

ndiy - thanks for the technical info, I like to hear that stuff. There's no end of people on t'internet saying Portland's no good, but not backing it up with the chemistry. However, as Mike's Mix has stood up to 50 firings there's something good going on there - maybe the Portland decays, but the cat litter holds it all together? Anyhow, I'll be giving it a try - often things which shouldn't work actually do, witness the endless debates about HSS vs carbide indexable tooling.

I mentioned this to a bloke in the pub (a ceramic artist for whom I occasionally do metalworking) and he's going to pick up a bag of the fondu for me. So I have 100 litres of Perlite,, 40 litres of cat litter, 25kg of Portland, and 25kg of Ciment Fondu ( on the way). I shall experiment and post results!

Robin

The ability of any cement to withstand temperature depends on the ratio of alkali to aluminum/ silicon oxides. Portland cement is not the best because of the high alkali (lime) content. Adding additional clayeffectively reduces the lime content and thus increases the temperature resistance.

Mike

Unfortunately the guy who was going to pick up the ciment fondu for me hasn't made contact after his initial enthusiasm, so no pics of the project yet. I think I'll just go ahead with Mike's mix and see what happens. Because this is a a bit bigger than the furnace Mike described in his article I can't make the internal form with a paint bucket or whatever, so I'm thinking to make it from hardboard/plywood and just burn it off when the refractory has set. Is there any reason to think that wouldn't work?

Ta, Rob.

Hi All, I have some experience of furnace making and have made my own wheel castings in iron. I have tried several of the home recipes and found that they were no good for high temperatures and did not last even for aluminium. Buy the castable refractory , I used 1550 degree C which I got from a chimney lining specialist. It only cost about £30 for a bag and that was enough. I used the waste oil furnace design from the Artful Bodger's Waste Oil furnace and found it worked well.