Lip on dome bricks using a tramell

[TEDFB]

[TEDFB]

Hi Guys, going back to the door, knowing that thin stainless warps more than a thicker one, my question is will a thicker one draw and therefore loose more heat through the insulated door than a thin one

[Giovanni Rossi]

Hey guys, hope you are all doing great.
Been very slow with the oven, other problems and maintenance on the property all wanting my attention.
I managed to get to the city and picked up some second hand 150mm (6") stainless flue pipes, I also needed 2 X 45 degree bends which I had to purchase new. Has anyone had experience in painting stainless.? The method and type of paint would help me a lot, remembering that this is all outside.

I researched this a fair amount in the summer of 2023 and found spray paint that worked well for stainless steel and spray paint that held up to flue temperatures. But, did not find any that would do both. Maybe there are new products or other builders who have found one.

[david s]

Try muffler paints, they may work.
Left unpainted, f it’s a single flue pipe it will not retain the shiny stainless appearance. It will go a kind of pewter grey colour that I personally don’t find unattractive, it is what it is. My oven and pipe are around 17 years old.
Another option is to use a double flue pipe and because the outer pipe doesn’t get so hot should retain its shiny stainless appearance.

[david s]

Here's an oven that's two or three years old that has a double flue and the outer pipe remains nice and shiny. Because the pipe is supported at the top where it penetrates a pergola I used a 6" pipe around the inner 5" one. There's some ceramic fibre blanket stuffed between the two pipes both at the bottom and top. This worked very well to centre the inner pipe inside the outer one as well as providing some insulation there. The normaldistance between pipes is 1", but with this oven it is only 1/2" because it's a 6" pipe surroundinh a 5" one.

[rsandler]

Hi Guys, going back to the door, knowing that thin stainless warps more than a thicker one, my question is will a thicker one draw and therefore loose more heat through the insulated door than a thin one

Probably not appreciably; my thinking with the door on my first oven (a sandwich with 14ga mild steel on the outside and Cal Sil board inside) was that the inner layer of steel would serve as an additional small bit of thermal mass, potentially handy for even cooking when baking bread. While technically that means some heat energy is in the steel rather than the air or the bricks, it isn't going to be noticeable compared to a thinner gauge shell. Note that if you are wrapping insulation in steel you probably don't have to worry quite so much about warping since you'll have some kind of structure rather than just a single sheet of steel.

[david s]

Whatever you try, use will prove it successful or not so try it and report back.
Whilst a thicker mild steel inner door panel will be less susceptible to warping it will also contribute to increased door weight. Both mild steel and stainless are very conductive, mild steel way more than stainless. The steel sides of the door also easily conduct heat from the inner panel to the outer one. Maybe this could be reduced by having the front and sides thinner with perhaps the sides perforated to reduce conduction.

[TEDFB]

A big thank you to you guys who have taken the time to share your expertise and experience in this build, my knowledge in these matters is limited.
I think that I will be using a lot of your advice and continuing with the project in the near future, and will keep you posted on what I have done.
Have a great day

[TEDFB]

Hi guys how are you doing,
I am slowly making progress with my oven. I have done the drying out of the dome with progressive fires. There were some (I think) minor cracks.
My next Question is.... After I have fitted the ceramic blanket and plaster it with Vermiculite / cement, do I make another fire to dry out the Vermiculite plaster, or is it best to leave it a couple of days to dry? Basically because I will put a final layer of waterproof plaster on as the oven is outside, and I seem to think that the Vermiculite plaster will not dry if it is covered by the waterproof layer.
Any advice on this will be appreciated.
Enjoy your day

[david s]

A lot depends on how thick you make the layer. I use around 35mm thick 10:1 layer and give it a week of drying in ideal conditions before applying the render coat. 35 mm is usually enough to restore a perfect hemisphere that evens out the lumps and bumps of the blanket. If you need to go thicker do two layers with a week drying for each.

[TEDFB]

If I have 3 layers of ceramic blanket, can I skip the Vermiculite layer on the dome

[rsandler]

You can, though it's a pain getting stucco/render/plaster to stick to ceramic blanket, particularly the large clumps necessary to smooth out bumps in the blanket. I did it, more-or-less successfully, on my first oven, but it was an exercise in frustration. I have not done an oven with a vermicrete layer (I did an enclosure on oven #2), but by all accounts, including David S's comment above, a thin vermicrete layer gives you a good base for the final plaster layer.

[TEDFB]

Once again, thank you for your valued replies