My first attempt for 42" oven / changed to 36"

[George_M]

Hi,
A week to wait is it enough time before start curing fires?

[George_M]

I made a door just for the curing fires and then i will upgrade it for better view.

[George_M]

I made 2 videos from the construction.

[George_M]

Hi,
Today i start curing my oven.
Temperature fire was 100-140F.
I had some cracks but i think it is from the thin layer of cement coat outside.
Inside i didn't see anything but i will check it again when it cool down.
No smoke or heat comes outside.

[Lburou]

I still remember the good feeling during the first fire in my oven! I had some cracks too. Bigger than those...smoke came out. Your oven will be fine. Congratulations! Be sure to keep it dry until you are finished with the weatherproofing.

[George_M]

I inspect it inside and I didn't see any cracks neither hairlines..
It's a good start !
My oven is under a wooden roof so i wil not have problem from rain.
I will continue with the second fire in few next days.
How much time required to keep the fire ?Need only to go for the required temperature or to keep it for long time ?
Thanks Lburou!

[George_M]

The second fire with woods finished today.
I saw little smoke outside of dome on the top but i don't know where it comes because i didn't see any crack from inside..
I have cracks only outside witch is the cement layer.

The only crack that i get today is in the entry.
The fire reach 200-250F in the oven but the bricks at the center of the dome was almost 600F.
I have a question here.
I read the oven curing topic and the tempratures that required is for the oven inside or for the center dome that the fire heats first?

[George_M]

Here is the crack at the entry.
If you see the 4th photo the crack is only outside of the dome and as it comes to the entry arc i get a real crack.
Any ideas what to do?
When it cool down,i will search insde again for cracks.

[david s]

The crack in the position you describe is quite common in ovens that have no thermal break or expansion joint between the oven and the flue gallery. This expansion joint allows the expanding oven to move a little without putting stress on the outer arch of the flue gallery. The other problem is the uninsulated flue gallery itself. Stress on the refractory is increased when the inside gets hot but the outside remains cool. By insulating around it this temperature difference is reduced and thereby reduces cracking tendency.
Don't worry about the crack, it probably won't get worse. As they say there are two kinds of ovens, those with cracks and those with owners who lie about their ovens having no cracks.

[George_M]

David,is good idea to stop the curing fires and to insulate my oven to avoid big difference in the temperature between inside and outside?
My oven is almost two months when I finished the dome until my first fire.
Or to continue the curing until full fire ?
Thanks

[George_M]

Today i finished the cover with ceramic blanket.
I made 2 layers of it.
It's time to make the perlcrete insulation layer now.Which ratio is good for dome insulation?
Maybe 8:1 or to go 10:1??

[david s]

I use 10:1 which is about as lean as you can go, but still being a workable mix. I also add a handful of powdered clay for every litre of cement which helps make it more workable.

[George_M]

Can I use chamotte sand in the mix instead of fireclay ?
It is fine sand not grains ..
How much need to add in the perlcrete mix?
10-1-0.5 bucket is it good enough ?
Thanks David!

[david s]

No, sand or chamotte will make the mix stronger, but will reduce the insulating capacity of the mix. Use powdered clay which will impart some stickiness which helps in the application. For every 10 litres of vermiculite add 1 litre cement and a handful of powdered clay. Mix well together dry then add 3 litres of water.

[George_M]

Ok david,i will buy clay to use..
Btw, Chimney ready!