Oven Curing Firing Your Oven Discuss Oven Curing in the Oven Management forums; My curing fires went well. But I do not think that I got my baking fire hot enough. How much ...

[jayjay]

My curing fires went well. But I do not think that I got my baking fire hot enough. How much wood does it take to heat a 3 x 4 foot oven with a wall thickness of about 8 inches. What size wood to most folks use? I am sure I am not using enough wood from what the post on this site are indicating.
I did not notice any cracks in the dome or in the oven walls. I did not see any cracks even near the chimney. I did notice that the smoke came out of the front of the oven, we have no door yet, and not up the chimney,
When the flames died down the smoke went mostly up the chimney, rather
than out the door.
I have been using light weigh dried mango wood. We did put a few good size
trunk peices in the fire, but most of the wood was on the smaller side, about an inch or more in diameter and about 12 to 18 inches long.
I have never seen a wood fired oven before. I never heard the term (wood fired oven) before and today I ''are one'', part of the old joke. You talk about being a dumb as a box of rocks, we I am that box of rocks when it comes to running this new oven. Help Please, the holiday of Thanksgiving is comming and I do not want to have an undercooked Turkey.
JJ
Philippines

[mgraban]

Originally Posted by james

Hey Fio,

Just reach the temperature, then let it cool down. You fires will get a little longer, but the idea is to go up and down without stressing anything.
James

By "let it cool down", do you mean to knock the fire down so it goes out right away?

[james]

Hi Mark,
Happy Holidays. Just let the fire burn itself out and the oven will cool down naturally. You don't really have to "do" anything, just let nature take over. I always say this, but toward the end, your oven will be getting into the 400-500º's, so you can start experimenting with roastings and grilling. Enjoy.
James

[Xabia Jim]

Cement is exothermic, meaning it puts out heat to cure.

firing a cement product too soon will damage the cement so the longer you can "cure" it before firing the better.

Also, the wetter you can keep your cement initially, the better. I am constantly wetting new cement, concrete etc. so it cures, not dries. Drying cement will cause it to crack whereas keeping it wet will allow it to cure and it will become stronger.

Rember, concrete continues to set up for years! Old concrete is much tougher to drill or break up than younger products.

...in my experience!

Now, I was told by a Spanish builder to use the "yeso" which I think is plaster of paris or gypsum. He said this will strengthen with the heat of the fire. Time will tell.

Happy holidays.....the oven is warming for the weekend cooking!!!

[Hendo]

All useful information here. From my experience, enough emphasis cannot be placed on the importance of keeping newly poured concrete moist. Two things affect concrete strength more than most people realise – water in the mix, and water (or lack of it) during the curing process.

Additional water in the mix makes the concrete easier to pour but decreases its strength. Concrete delivery drivers seem to love adding water when they pull up at a site, sometimes without even asking. So the strength guaranteed by the concrete supplier goes out the window!

On curing, the Cement and Concrete Association of Australia, in its publication entitled Design, Control and Characteristics of Concrete states:

“The increase of concrete strength with age continues so long as drying of the concrete is prevented. When the concrete is permitted to dry, the chemical reactions cease. It is, therefore, desirable to keep concrete moist as long as possible. The best practice is to moist cure the concrete continuously from the time it is placed until it has attained the desired quality – usually a minimum period of seven days is required.”

An interesting graph in this referenced publication shows that 28 days after pouring, concrete allowed to dry out will have a compressive strength of about 70% of concrete which has been continually moist cured.

After the concrete has firmed up after the pour, it should ideally be covered entirely with a plastic film to prevent it drying, and it will moist cure naturally. This is preferable to hosing with water periodically, as the concrete will cycle between wet and dry, rather than simply retaining the moisture present in the original mix when encased in plastic film.

[CanuckJim]

Hendo,

I agree entirely with the notes on keeping fresh concrete damp. This is particulaly true with refractories. When I poured the refractory slab (LaFarge Fondue and aggregate) for my oven, I bought a roll of burlap, covered the slab with it and kept it damp for about a week. This method adds strength and also retards shrinkage. Followed the same procedure with the cladding.

Jim

[Hendo]

In terms of heat curing the refractories, as opposed to moist curing the mortar, I’ve found the following spec sheet for heat-up procedures for refractory products, albeit in degrees Centigrade, rather than Fahrenheit (I’ll leave it to you to do the conversions).

Quite interesting (and hopefully useful), but note the caveat in the top left text box!

[CanuckJim]

Hendo,

Interesting stuff. I ran into something similar for kiln curing. It would probably be difficult for us to use the procedure under such controlled conditions, though. You'd have to be out there constantly for hours on end. Still, it's probably the best way for ultimate strength.

Jim

[jengineer]

The chart starts out at ambinet conditions. You then ramp up at ~120 F/hour until you hit 400 F. (it might be easier to ramp up at 100/hour to 400 F = 4 hours). From 400 F you then ramp up at no more than 400 F / hour until you hit the max operating temp say 2190 F. Getting you oven equlized at 2190 is a snit on the hot side.

[RTflorida]

I hope to complete my dome this weekend, my question - does it make sense to go through the curring process BEFORE insulating?? I thought that I read somewhere early in my research that curring the dome prior to insulating allows you to "patch" any cracks that occur in the dome and refractory mortar layer...then insulate/finish and cure again.

Does this make sense, or should I just go through the curring process once, after insulation?? I'm doing an igloo with 2" blanket, 4" perlite/cement, then either stucco or mosaaic tile.

RT