Portland Cement as refractory fill?

>>971672
Bamp?

>>971684
C'mon /diy/, halp. If it's a stupid idea, then tell me. I already suspect it is but would like to have a second opinion.

diy is a very slow board, give it time.

>>971768
Good point, I forget that at times.

Portland cement starts to turn back into its original constituents and lose its strength at high temperatures, so it will break down over time in a furnace.

A better bet is to make your own water glass/sodium silicate solution (or buy it if it is easy to get in the US) and using that as a high temperature cement in a furnace.

Look up clkindred on Youtube, he has the details on how to make sodium silicate (it's made by dissolving the silica gel type of cat litter in sodium hydroxide), as well as furnace building videos.

>>971777
Thanks for this, especially the lookup. The perlite-sodium silicate-water combo is going to be easy and much cheaper (about $30 based on amazon's price list) than actual refractory cement.

>>971672
bricks are heavy so you might want to post your state. true furnace/crucible bricks are hard to find as they are made under tremendous pressure. there is a place that makes them in WV. I think there is a west coast place too. You can mix your own refractory but its largely not for direct contact with the material. I can post more info later. what state are you in? do you already have a crucible? etc. you can also order firebrick under different ratings.