DIY dome casting

[matty]

I was looking into buying a precast dome for a trailered oven but now that I saw joeys precast oven I want to do it myself!

I was thinking of using a steel mesh to hold together the dome? I would like to mix my own refractory material? or is that a bad idea? any suggestions? what would be the best DIY castable refractory mix?

thanks guys!

[david s]

The best castable refractory is one that is supplied by refractory suppliers. It will probably be a product that way exceeds a wood fired oven that only gets to about 500C. Most of their castable refractories are rated to well over 1000 C, although the fast heat up times we use tend to push the limits of their thermal shock capabilities. They contain all sorts of ingredients which include fibres that burn out leaving spaces for moisture to escape without blowing the material apart, plasticisers to help get the material more fluid without adding excess water, stable aggregates etc,etc. Good luck if you want to make up your own brew, but no guarantees how it will work. The proprietry castables are not cheap. If you want cheap try mud- has been used for centuries.

[djag12]

Take a look at this page. Gives all the resources you need to make your own. It is for a kiln but I think should work. I just plan on buying. I found a source near me for $23 for 55 lb bag.
ArtistPotters - Refractory Castable

[david s]

By all means have a go at making up your own brew, but bear in mind that a WFO does not get hot enough to create the quartz inversion that turns clay into a fired product that will not return to mud when it gets wet again. It relies on the calcium aluminate cement to make it permanent. If you have large quantities of unfired fire clay, in the form of powdered fire clay, in your mix, this will not get fired like it would in a kiln. Also take note of the very careful firing schedule to expel the water. Do not think that once you go over boiling point (100C) that you are safe. From my experience steam explosions in pottery seem to occur at around 300C.

[matty]

thanks for the info guys.

what do you think about laying a steel reinforcement mesh in the forming to make the dome stronger and less prone to cracking from vibration ect. from the road?

[david s]

I used chicken wire ( the small stuff with holes about 3/4") in the outer shell, but I don't have any reinforcing in the dome. The recommended reinforcing for castable is stainless steel needles. Both my dome and outer shell of my mobile are holding up well and the oven gets lots of use and travels a lot.