Quick question.

[enzo]

After a firing of about 4-5 hours at pizza temps, should the outside surface get warm?

[Les]

Re: Quick question.

Not if you are well insulated - how warm is warm?

Les...

[enzo]

Re: Quick question.

Warm as in, nice to touch on a cold day. I can leave my hand on it for as long as i like without it getting too hot, but definately warm. I have used shiralite (an insulating cement) about 20mm thick, 2 woolen blankets and about 45-50mm of ordinary cement mortar all over.

Does that sound reasonable?

[Les]

Re: Quick question.

If the blankets are 1 inch thick - that should be plenty. My dome seems to be ambient the few times I touched it. If it retains enought heat to bake, I don't think you have a problem.

Les...

[texassourdough]

Re: Quick question.

Exterior temperature is very sensitive to the water level in your oven. When mine is wet the outside gets hot. When dry it stays pretty much ambient - warm (especially near the chimney) but otherwise not hot.
Jay

[nissanneill]

Re: Quick question.

Enzo

and about 45-50mm of ordinary cement mortar all over.

This cement mortar is also acting as thermal mass, ie. it is receiving the heat transmitted through your insulation and absorbed by the top coat of cement render.
Little you can do about it now without removing it and adding more blanket insulation and then re-cement rendering. It is not a lot of heat loss after 4 to 5 hours so put it down to experience and use more insulation on your next oven.

Neill

[david s]

Re: Quick question.

Ovens that are insulated really well can be a bit of a nuisance in that you have to wait until 2 am to put in a loaf of bread that you want to cook after pizzas. We found that we would burn a dessert pie because the oven was too hot. You probably only need really good insulation if you are baking lots of bread or are silly enough to live in a climate that gets down to below freezing. My oven gets warm on the outside and thats one of the ways I know when the temp is right. When the warmth on the outside has got right to the bottom of the dome I know she's ready.

[Frances]

Re: Quick question.

if you are baking lots of bread or are silly enough to live in a climate that gets down to below freezing.

Har har har, thanks david! ...How about "all of the above"?

enzo, I think it sounds as if you are fine, too. My oven has one warm spot, where something apparently went a bit wrong with the insulation. But I have never actually had it at pizza temps for four hours, so who knows what it would be like then?

Each oven cooks differently anyway, so instead of worrying about the insulation (which sounds fine btw), now's the time to learn about your ovens ins and outs and how best to use the enormous amount of heat it is retaining. The question isn't: did something go wrong? but rather: do you bake bread two hours or four hours after pizzas?

[RTflorida]

Re: Quick question.

Enzo, I think you are fine. On an igloo style oven it is almost certain that heat will eventually make it through to the outside surface. It does not happen often if you are well insulated, but 4-5 hrs at pizza temps WILL transmit through.
My oven has 2" of blanket and 3-3 1/2" of perlcrete, 1/2" mortar render, and finish in mosaic tile. This past spring I had a major issue with rain infiltration and spent several days driving water out (no, I did not follow the curring fire methods). I was pissed and built the biggest fires I could keep lit. by the 3rd or 4th day I was able to keep a scary fire going, and did so for several hrs each day (my IR was in error mode - over 1000 F). On those days the outside of the dome was pretty warm - the IR showed about 135-140 F. Remember this was after an all day fire, with at least 3-4 hrs of "scary" fire over 1000F.

I guess the questions to ask are - Does your oven perform to your satisfaction? get up to temp quickly? hold heat for all of your baking and roasting needs?

RT

[david s]

Re: Quick question.

" I was pissed and built the biggest fires "

In Australia the mix of being pissed and playing with fire is considered dangerous, but we do it regularly. Excessive alcohol consumption is usually referred to here as "getting pissed" rather than the American expression "being pissed".
Thus when an Australian is pissed he's usually happy, whilst the American is grumpy.

[RTflorida]

Re: Quick question.

david, I love it. Next time I will concentrate on getting pissed in order to avoid being pissed. My wife is going to love this bit of logic.

RT

[GianniFocaccia]

Re: Quick question.

David, Thank you for clarifying the American vs Aussie distinction of 'pissed'. Those unlucky few who have wives who become grumpy because our WFO obsession can tell you that getting pissed on can certainly make us pissed off.

John