Wood fired oven corner build in Grafton NSW

[broschb]

Re: Wood fired oven corner build in Grafton NSW

Looks fantastic, just in the planning stages for mine. I really like how you have enclosed it. What did you use to cover the top?

[reccymech]

Re: Wood fired oven corner build in Grafton NSW

Pizza oven envy

[Greenman]

Re: Wood fired oven corner build in Grafton NSW

Looks good. That first food would taste great regardless but I have found the oven to be very forgiving at regular cooking temps.

Makes all of the work worthwhile.

[Wayne73]

Re: Wood fired oven corner build in Grafton NSW

The crack fairy sat on my oven!

Today I thought I should inspected the top outside of my oven.I started to push back the perlite and noticed a crack starting at the key stone going down to the center of the arch.
Crap I thought, but hey one crack I can live with that.Then I thought I should have a real good look, so I got a broom]and swept all the perlite dust away and that's when I felt sick.
Not 1,2,3 or 4 but 5 cracks! The mortar around the key stone has cracked right around it and then from there there's five cracks heading down to the base seperating the dome in five parts.

the key stone


from the top


and the inside


I know you can expect some cracking but this crackadiculous!

I only lit the five times with small fire's as I dont flue yet,the last got up to 250c maybe that was to hot. Hopefully it doesn't crack any more when I get it fully up to temp.

Should I try and fix it by grinding out the mortar and re mortar or just keep an eye on it for now?

[oasiscdm]

Re: Wood fired oven corner build in Grafton NSW

Hi Wayne sorry to here cracks forming.

My view here is fire and brick will expand and crack. While going through hearing and cooling cycles. Its unavoidable. With only perlite as loose insulating fill, the bricks although mortared in place aren't locked in.

This is partly why when I spoke to a refractory commercial oven builder, that I was told to place a 1 to 2 inch layer of shiralite, or similar and then the fire blanket. Since your oven is enclosed now not sure you have room. There was talk recently I think on damon's thread as he put a refractory render layer over his dome. I would enclose the dome with a cement based render layer. But I am no expert just looking at possible solution to lock all your good work on place I can not see loose fill doing this.

The cracks seem to follow the straight mortar seams where the bricks are not on bond
(Stretcher bond)
What do others think?

[david s]

Re: Wood fired oven corner build in Grafton NSW

When oven curing you need to avoid direct flame impingement which causes uneven heating and therefore uneven thermal expansion. As lots of your joins coincide, the stress takes the path of least resistance. Did you read the whole thread on curing? Most people go way harder than they should and wood flame is difficult to control. Unfortunately we are banned fro talking about gas.
Don't bother attempting to fix the cracks, it is usually unsuccessful and they are unlikely to get worse anyhow. The reason many kilns are built with mortarless joins is so the refractory can expand, contract and move at the joins. It is also why most floors have smaller sections or bricks that are not mortared. Just keep firing. The dome can't collapse.

[Bacterium]

Re: Wood fired oven corner build in Grafton NSW

Wayne it does get a bit disconcerting when you discover the cracks.......yet in the end expected at some level.

I tend to agree with Colin and Davids posts.

my recent experience..........
I found my cracks didn't appear until the last big firing, so this was pre the dome capping layer. And one of the cracks actually went through a brick, even though I was careful with the bond. I put it down to (my theory):
- the large temperature difference, between inside compared to outside (without insulation)
- that I built the floor inside the dome and not paid attention to a couple spots where the mortar build up between floor edge and dome side. I read the cardboard trick too late.
-using second hand bricks (eg. inconsistent or mixed batches).

So basically once it cracked it pretty much remained there (eg. they didn't open/close much between hot and cold temps.) From there I:
- re-wet the dome drizzled the last lot of hi temp mortar along the crack lines
-straight away put a 30-50mm capping render layer over the dome with chicken wire
-let it dry slowly for over a week
- then applied 3 inches blanket
-another layer of chicken wire
-vermicrete coat to bring the shape back.
-then re-cured with very slow curing fires for another week

With no final render coat (outer) on a lot of the moisture is migrating out. On the w/end I barely got it to pizza temps so no extra cracks and previous existing cracks (refilled) have not re-opened......so far so good.

.....do you "cap" your dome to lock it in?......hard to say as I have built 2 ovens as "exposed" domes and haven't experience the dog house style

......I've been in the dog house but thats another matter

[oasiscdm]

Re: Wood fired oven corner build in Grafton NSW

Lol Damon re last comment

[Wayne73]

Re: Wood fired oven corner build in Grafton NSW

Just keep firing. The dome can't collapse.

I was hoping someone would say that.


I guess I should have studied the curing oven section a bit more. Anyway I'm just going to keep an eye on it now with some heat beads for few days to make things don't any worse, to late I know.

straight away put a 30-50mm capping render layer over the dome with chicken wire
-let it dry slowly for over a week
- then applied 3 inches blanket
-another layer of chicken wire
-vermicrete coat to bring the shape back.
-then re-cured with very slow curing fires for another week

With no final render coat (outer) on a lot of the moisture is migrating out. On the w/end I barely got it to pizza temps so no extra cracks and previous existing cracks (refilled) have not re-opened......so far so good.

Thanks Damon, If the cracks get worse ill look in to it and I was thinking how do you know if your cracks have reopened with the blanket covering everthing ?

On I brighter note I ordered my flue from a local sheet metal place, only $77 for two meters of stainless steel.

[Greenman]

Re: Wood fired oven corner build in Grafton NSW

What the eye doesn't see the heart doesn't grieve.

Those who cover the dome before the first fire will never know.

[Wayne73]

Re: Wood fired oven corner build in Grafton NSW

I know I told myself I shouldn't look...but then I did

[Bacterium]

Re: Wood fired oven corner build in Grafton NSW

.....look but don't touch

I also got very worried about it either falling down or failing but hey as some of the brickies on here say........ A dome is one of the strongest self supporting shapes.

[Wayne73]

Re: Wood fired oven corner build in Grafton NSW

Installed my flue today, though I haven't sealed it, god I hope it doesn't rain tonight.

Its singled walled stainless and It ended up costing me $70



The flue sitting on the brick work.An inch on the end of the flue has been bent at a 90 degree angle then siliconed in place.Because it is going through the roof I don't think it needs to be bricked in to hold it in place, it seems solid enough.

[Wayne73]

Re: Wood fired oven corner build in Grafton NSW

Its going through Spanline so what I did was melt the Styrofoam back 4" or so with a hot air gun and Im going to fill the cavity with hebel and then seal it

[oasiscdm]

Re: Wood fired oven corner build in Grafton NSW

HI Wayne

I was thinking of square or is it rectangle ?

Looks great. Hmmmmm thinking I might go square too but double walled.