DIY castable experiences

[Sgrenier35]

I’ve been lurking on this forum for a few weeks mulling over how I would like to construct my WFO. I’ve decided to go the castable route and would like to use the 3:1:1:1 home brew recipe. I’d like to hear from people who have used this method. Hopefully some of you who have done this can chime in with your experiences. I’m really curious to know how your ovens have held up over time? Thanks

[david s]

Seven years ago two customers came to me wanting to build a cheap oven. I recommended using home-brew as a castable. I never heard back from one of them but the other says his is still performing well although I don't know how frequently he uses it. The home-brew relies on portland which begins to fail at around 300 C. The lime however, doesn't begin to fail until around 500 C. The clay in the mix helps it become more refractory and in practice the brew works perfectly adequately as a mortar. That's why I recommended trying it as a castable. A proprietary castable designed for service in the 1400 C region contains calcium aluminate cement that is able to withstand those temperatures as well as high temperature aggregates, but it really only gains its true strength when fired above 1000 C when the material becomes sintered.