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

[Robarb]

Nick J C Mullster how many 100L bags of vermiculite have you ended up using in total?

thanks

[Nick J C]

Less than 2, but I used Thermolite blocks for base

[Nick J C]

Nick, have you considered tiles for the outer shell? Is it possible to waterproof tiles? It could look pretty.

I have, but I will probably end up constructing a roof (with no walls)

[Nick J C]

time lapse showing sandcastle construction, homebrew, and vermicrete of my build

[david s]

Nice work, thanks for doing that. There is a problem when having no blanket layer over the dome as it means your vermicrete layer is much thicker. This means that the large amount of water added to the mix (around 70 litres if you used 2 bags) needs to be eliminated. When the surface goes white you will think it’s dry, but it won’t be deeper in. This is why I recommend doing it in layers around 1.5” thick and allowing it to dry before creating subsequent layers. If you push out the water too fast the vermicrete will swell and crack. Get a cheap garden moisture meter and push it deep into the vermicrete about half way down the dome. This will tell you how moist it is against the inner casting.

[Nick J C]

Hi david s was playing with a new video editing app. I have 2 inches of ceramic blanket, and approx the same of Vermicrete....will take a little longer to dry I guess, so I won't be rendering it for a while

[david s]

Ok, my apologies I wasn't viewing it in full screen and missed the blanket. so you can largely disregard my cautionary post. With the blanket between the inner dome and vermicrete layer you won’t have wet vermicrete in contact with the inner dome. In your case the blanket also acts as an expansion joint. All good.

If you are considering a roof, which is the best solution imo, it may end up costing you more than the oven. This is my solution for my kiln. A bit over the top.
https://community.fornobravo.com/for...137#post394137

[Mullster]

Nick J C Mullster how many 100L bags of vermiculite have you ended up using in total?

thanks

Robarb I’m a small way into my second having done a 4inch base underneath the floor. Hoping the remainder of the bag will be enough for the layer after the blanket on the dome.

[Nick J C]

more work on door whist waiting for dome to dry out. Added glass fibre rope seal, and welded up a storage bracket. Keep it away from small hands

[Nick J C]

First curing fire, probably a bit too much flame but no cracks spotted on cooling..... Bit Smokey....hopefully just because not fully dry yet. Only got seasoned softwood at the moment, and understand this isn't the best when it comes to eventual proper fires. Also got the thermometer into the door, and some aluminium trim to help prevent it chipping

[david s]

Your inner casting has had sufficient damp curing and the strength of the vermicrete layer doesn't really matter as it's really weak and is only there to provide a bit more insulation and to provide a firm substrate to render against. You could use the oven in its present state for weeks provided you keep rain off it. Don't get too excited with the fires, rush things and risk damage. The 7 fires in 7 days getting progressively bigger is a simple and practical guide. Read the whole of the curing thread.
https://community.fornobravo.com/for...curing#post833

Tou've done a great job.

[Nick J C]

Thanks for your, and the forums help....the wonders of modern connectivity

[Nick J C]

It's a themed birthday... Mullster style.... Must be getting close

[Nick J C]

Day 4 curing fires, less gentle. Interesting that there is obvious moisture coming out of the Vermicrete, which was pale all over, but darker moist patches emerge on the top of the dome Vermicrete after I leave the oven hot with the door sealed. No cracks to report yet (famous last words)

[UtahBeehiver]

There is an amazing amount of water in these builds, I have seen water seeping out of the bottom of ovens during the curing stage, Remember when water sublimates from liquid to gas the volume of water increase by factor of 1500 plus times so if not released slowing, pressure builds up and cracks the vcrete.