42" in Hungary by Slovak guy ;)

[alex.g]

Re: 42" in Hungary by Slovak guy

drying


and first crack appeared, in a strange place




got a tube of heat resistant putty, will fill it later

Guys, how do you prevent entrance firebricks from moisture and rain? Do you have covers or something? i think firebrick don't like moisture for a long time

[cobblerdave]

Re: 42" in Hungary by Slovak guy

G'day
Firebrick loves water and will soak it up water unlike a house brick which is designed to caste off water.
I live in the sub tropics, lots of rain in short bursts my own personal preference to the problem of a wet oven was to house brick over the whole thing. Not full thickness brick but 1/2 thickness. I worked for me.
If you don't like the look some serious rendering including a cover door to protect the entrance hearth bricks.
Regards dave

[Greenman]

Re: 42" in Hungary by Slovak guy

Cracks are pretty standard. A bit of mortar will fill them and different mortars behave differently. Just fill the cracks as it settles.

[alex.g]

Re: 42" in Hungary by Slovak guy

I know that firebricks will soak, but what about subzero night temps and wet bricks from a day?

And yes every oven will crack, but i was expecting dome crack :-) will fill it with hightemp putty

[Gulf]

Re: 42" in Hungary by Slovak guy

I know that firebricks will soak, but what about subzero night temps and wet bricks from a day?

And yes every oven will crack, but i was expecting dome crack :-) will fill it with hightemp putty

Wet bricks and green mortar will expand, spall and crack in freezing weather. I don't live in a subzero climate, but I did tarp and place heat lamps inside the oven to protect it on freezing nights. That should be done for any concrete or masonry until it is dry.

Your outer arch crack may be a result of there being no expansion joint between the clay liner and the outer arch. I can't really be sure by looking at the pictures, and that may not be true in this case. But, unlike materials expand differrently when exposed to heat. Even, like materials expand at different rates, if they are not heated at the same rate.

[cobblerdave]

Re: 42" in Hungary by Slovak guy

G'day
I expect cracks from a fired oven but not one that is unfired from what I can see.
One pic has steam rising from the back of the oven , another wood stacked in the entranceway but none can I find soot staining at the entrance or chimney pot. I live in the sub tropics but even I suspect freezing has something to do with it . A pot full of burning charcoal would go a long way to both drying and keeping any water from freezing.
Its a shame to see an unfired oven crack a real shame
Regards dave

[alex.g]

Re: 42" in Hungary by Slovak guy

exactly, i was expecting dome to crack, not the entrance.
But, it cracked after secong fire, it was not like crack before first fire

I put every brick into water when putting all together. so probably these were expanded a lot and when dried those shrinked this way.
Every brick is not the same

Yesterday put some more fire, no more cracks, strange
Will fire today again

[cobblerdave]

Re: 42" in Hungary by Slovak guy

G'day Alex.g
Pretty obvious from the green grass there is no frost.
From the smoke coming out of that pretty advanced fire I'd be guessing that oven is still very "wet" without even seeing the steam rising off the surface in the secound pic.
Go slow Alex . Visible Steam ....means 1 ltre of water becomes 1500 ltres of steam, powers electric power plants and is still a powerfull thing inside a firebrick.
Keep the same size fire. You'll find the temperature will go up as the oven drys for the same amount of wood . Try to resist making the fire bigger each time .
It seems more ovens crack without insulation than with in the "curing " process. Why? I can't explain, as much as anyone who has been on this forum for any time. Always ... Always go cautiously. None of us want to see you have more cracks if at all possible
Regards Dave

[alex.g]

Re: 42" in Hungary by Slovak guy

Thank you a lot for kind words
Im keeping the same size fire , this one was slightly bigger that first ever, after which that mentioned crack appeared.
Yes, still a lot of water inside, coz the keep vapouring.

Yesterday got few wooden briquettes from a frined, fantastic thing.. it doesnt burnt with big fire, it fires loong with pretty stable temp. Will buy some packs today to continue curing.

[cobblerdave]

Re: 42" in Hungary by Slovak guy

G'day Alex
Those things sound like a good thing, a lot like burning charcoal, little flame but good steady heat over a long time .
Regards dave

[alex.g]

Re: 42" in Hungary by Slovak guy

update from the last week

used 2 rolls of blanket
2 bags of DuoContact
probably 8m (1m wide) of the wire net

[alex.g]

Re: 42" in Hungary by Slovak guy

there were no visible cracks (after curing) on the dome
soe used grinder to wider my single crack and put hitemp puty, plus fixed ceramic chimney parts with putty + hidens wirenet over putty on the seams

[alex.g]

Re: 42" in Hungary by Slovak guy

Yesterday made insulated stainless door

[Greenman]

Re: 42" in Hungary by Slovak guy

What is the insulating material you have used in the door?

[alex.g]

Re: 42" in Hungary by Slovak guy

FB Board i used for floor insulation
why?