Oven Curing

[herridea]

Re: Oven Curing

Curing your oven is an important step in the installation of any brick oven -- whether it is a Forno Bravo precast oven, a Forno Bravo Artigiano brick oven, or a Pompeii brick oven. Heating up your oven too fast can lead to cracks. You have invested a great deal of time, money and energy in your oven, so go slow, and cure your oven properly. If at all possible, don't schedule a pizza party the weekend your dome is finished.

After you have installed your oven, there is still a great deal of moisture in the mortars, hearth concrete, vermiculite, and the oven chamber and vent themselves. Each of these oven components was recently produced using an air-drying, water-based process. Simply letting the oven stand for a week does very little to "cure" the moisture out of them oven. In fact, the Forno Bravo precast oven producer recommends letting the oven stand for a week after it has been assmebled before "starting" the curing process. Thicker sections of concrete can take many weeks to cure.

You are trying to avoid two problems. First, any mortar or concrete that dries too fast shrinks and cracks. These cracks can let hot air and/or smoke escape from the oven chamber. Second, if you bring your oven up to heat while there is still sufficient moisture in the oven dome or mortars, you will actually create steam, which can produce hairline fractures, or even cracks in your oven. I heard a story (possibly an urban legend) from one of our installers who used to work with one of our competitor's ovens, where the home owner lit such a large fire in a non-cured oven that a chunck of the oven dome actually blew out the front door. Hmmm. Maybe.

Also, using a space heater can help, but only so far. It is not an alternative to fire curing. We ran a space heater in an assembled Forno Bravo precast oven for two days, then quickly heated the oven up, (don't do this at home -- it was an experiement to see what would happen to an oven that we have here) and we found that we created a very large amount of steam from the oven, mortars and vermiculite, which went on for hours and hours.

To be safe, here is a good curing schedule.

1. Let the oven sit for a week or so after you have finished the dome.
2. Run a series of seven fires, starting with a small, newspaper-only fire.
3. Increase the size of the fire each day by about 100F
200F
300F
400F
500F
600F
700F
800F
4. Let the oven fall back to cool as soon as you reach the temperature you want. It is important to bring the oven up to heat gently, then back down to cold, each time.
5. If you don't have an infrared thermometer, try this schedule:
Newspaper only
Newspaper and a little kindling
1 stick of 2"x3"X16" wood
2 sticks of wood
3 sticks of wood
4 sticks of wood
5 sticks of wood

James

Hi James,
Should I cure before covering the dome in vermiculite or after?

I would like to cure after to ensure that I cover the blanket from the elements?
Thanks
Dean

[dimitrisbizakis]

Re: Oven Curing

Hi James,
Should I cure before covering the dome in vermiculite or after?
I would like to cure after to ensure that I cover the blanket from the elements?
Thanks
Dean

You sure want to cure before, if you cover the dome you will trap the moisture in,my opinion is to use it AFTER curing 10 times for pizza and after cover it.

[herridea]

Re: Oven Curing

Thanks. I will go with your advice and cure before covering.

[Moose4Life]

Re: Oven Curing

Quick question just finished my keystone today! And it's 40 degrees and will be 30 tonight. I have a space heater in the dome covered with a tarp/blanket/tarp. I sponged the joints before closing but I want to keep it moist while keeping it above freezing. The space heater is at its lowest setting which is probably 55' f in the dome. Think I should keep a bucket of water in the dome to keep the moisture up?

[Mdog91]

Re: Oven Curing

I would think that it would stay moist at 55f especially since you just sponged it. That being said??..a cup of water wouldn't hurt and may help the peace of mind.

[K79]

Re: Oven Curing

I don't think it's necessary to put the water in there. Mine was curing at around 80 F with no water in the summer so 55 f no prob. I had pretty tight joints in my dome.

[cobblerdave]

Re: Oven Curing

Quick question just finished my keystone today! And it's 40 degrees and will be 30 tonight. I have a space heater in the dome covered with a tarp/blanket/tarp. I sponged the joints before closing but I want to keep it moist while keeping it above freezing. The space heater is at its lowest setting which is probably 55' f in the dome. Think I should keep a bucket of water in the dome to keep the moisture up?

Gudday
if its commercial high temp mortar sorry can't comment, other than telling you to check to check with the manufacturer.
If you curing some homebrew mortar (as opposed to heat tempering the dome), I recon you being safe and prudent. the space heater will stop it from freezing and watering a cement product during curing is always a good idea.
I live in a hot climate where any cement work is usually damped daily and covered from the hot sun. protecting it from freezing is novel concept to me
go well
regards dave
PS http://www.fornobravo.com/forum/f16/....html#post3871
I think this explains things best...thanks Tszar

[Moose4Life]

Re: Oven Curing

Thanks, it's a home brew and all the joints are tight except the keystones, could never get them perfect!

[Jim Bob]

Re: Oven Curing

I wanted to ask James another question about the oven curing process. My oven is in its fifth year of operation. Recently there has been some real time gaps between cooks, mostly due to inclement weather. Anyway, is there a length of time between cooks that I should consider redoing the curing process due to accumulated moisture in the oven?? Rather than just firing it up hot to 7-800 degrees again? I haven't been doing it but thought it might be better to do so.

Thanks,

Jim Bob

[david s]

Re: Oven Curing

Just give it a couple of long burns before doing the fire from hell. You don't need to go right back to the initial curing fires.

[Moose4Life]

Re: Oven Curing

Anyone on this thread point me to a simple way of making the door for the dome? Thanks

[david s]

Re: Oven Curing

Try starting here.
http://www.fornobravo.com/forum/f9/s...tml#post157363

[Moose4Life]

Re: Oven Curing

Thanks. Also is there any merit to cutting away the excess vercrete that goes out past my dome?

[david s]

Re: Oven Curing

Yes, probably. Just remember that the vermicrete acts like a wick, so unless sealed it will suck water into itself.

[Moose4Life]

Re: Oven Curing

Will do that. Thanks. Not the seal part , suppose it's not nec after I cut the excess