Record of my 32" Homebrew cast oven, on a brick base - West Midlands, UK

[Nick J C]

Ceramic board over Thermolite blocks, and fire bricks cut. (Soaked in water and diamond angle grinder cut surprisingly easily.)Hoping for some good weather tomorrow to build sand castle form and get casting.....home made tools at the ready

[sergetania]

Looking very good! Good luck with the casting!

[UtahBeehiver]

That homemade trowel looks very familiar you can use it to install the vcrete as well.

[Nick J C]

Worked a treat

[sergetania]

Shame it's just a temporary form because it looks amazing! Waiting to see the dome.

[WoodywWun]

How are things going on your build Nick?

[Nick J C]

Layer of cling film over paper. Homebrew standard mix with polypropylene fibres and stainless fibres. Went up readily over a couple hours. Used concrete mixer to dry mix large batches and mix up with water for each smaller batch. Forgot rubber gloves under building gloves for first batch..... Won't forget again....lime nasty stuff
in barrow. Curved tool makes smoothing easy

[WoodywWun]

Thanks for the reply, Nick. It looks very good! Have you tried firing it up yet? Can I ask where you got your needles from?

[Nick J C]

I suspect 24 hours after casting, firing up would end badly.... Plan to get the insulation on first and give it a few weeks to dry it as per most advice

stainless needles.....only able to find one supplier but good price and service....

https://rockbond.co.uk/products/rock...-steel-fibres/

[WoodywWun]

Thanks for your reply Nick. So you decided to wait before firing? There seems to be various advice about but it looks like the consensus is 1 week to cure then gradually build the firing on a daily basis from 300 upwards? ...and fire it up with the blanket on but not any Vcrete?

I've just found that Victas do the needles as well.

[david s]

I think it’s better to do the drying fires around a week after applying the vermicrete layer. Why lock in a whole lot of extra water in the insulation layer after you’ve just purged the inner parts of it.

[WoodywWun]

Thanks for your reply David. So the best method might be as follows?

1. Make the castings (two parts);
2. Take out the sand mould after 24 hours (if all appears stable)
3. Leave for one week, with maybe a plastic sheet over it if the weather is hot and dry (or in any event?);
4. Wrap with the ceramic blanket;
5. Apply Vermicrete
6. Leave for one week;
7. Start a daily firing, starting at 300ͦͦ C and letting it heat/cool gradually, then building a progressive increase in heat over one week.
8. Apply the final render/stucco layer.

How does that sound?

Also, can a hole be drilled in the oven casting to allow a probe thermometer to be installed or is this asking for trouble?

[david s]

Thanks for your reply David. So the best method might be as follows?

1. Make the castings (two parts);
2. Take out the sand mould after 24 hours (if all appears stable)
3. Leave for one week, with maybe a plastic sheet over it if the weather is hot and dry (or in any event?);
4. Wrap with the ceramic blanket;
5. Apply Vermicrete
6. Leave for one week;
7. Start a daily firing, starting at 300ͦͦ C and letting it heat/cool gradually, then building a progressive increase in heat over one week.
8. Apply the final render/stucco layer.

How does that
Also, can a hole be drilled in the oven casting to allow a probe thermometer to be installed or is this asking for trouble?

Yes to all. Good luck, you’ve prepared well.

[Nick J C]

Form work and sand removed....looks pretty smooth inside....just a bit of filling required.....on to the concrete cast arch

[Nick J C]

Polishing concrete to expose embedded glass, and testing the fit....Will lie a few mm from the oven to heat break as per david s advice.