UK 34" rounded square Oven Progress.

[Nev Grady]

Re: UK 34" rounded square Oven Progress.

Well Mr Dmun sir, teaching grandma to suck eggs springs to mind, if you know what I mean. Undercoat plaster was used for ease of application and for its quick setting properties. There is no way that it can absorb atmospheric moisture, or any other moisture for that matter. As explained previously, it is totally covered by a waterproof render which in turn has several coats of a top quality masonry paint.

In the unlikely event of any moisture ingress and the failing of the gypsum plaster, would it matter? It was used as a thin base coat for firming up the plasterer's mesh to ensure keeping its shape before applying the cement render. If it fails nothing is going to collapse!

[dmun]

Re: UK 34" rounded square Oven Progress.

a gypsym product? I wouldn't recommend this.
Really? Why not?

Gypsum products like plaster of paris and drywall will absorb atmospheric moisture when they are outside: they swell and stress whatever is on top or underneath, loose all strength, and fail.

There's a reason that plaster (gypsum) is used inside, and stucco (portland cement) is used outside.

[Nev Grady]

Re: UK 34" rounded square Oven Progress.

I can't go much more than 2 or 3" of insulation with a render outer before I run out of platform to put it on.

Is it possible to get extra width and depth by anchor bolting precast concrete lintels, or something similar, level with your hearth? They wouldn't be carrying too much weight.

[Nev Grady]

Re: UK 34" rounded square Oven Progress.

Translation = expanded metal lath
really? a gypsym product? I wouldn't recommend this.

Really? Why not?

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

thanks for the replies guys! some good ideas for me to work with! I never thought of plasters mesh!

I already have 2 layers of 25mm blanket, and decided I needed more, but I can't go much more than 2 or 3" of insulation with a render outer before I run out of platform to put it on.

[dmun]

Re: UK 34" rounded square Oven Progress.

I bought 3 large sheets of plasterer's mesh

Translation = expanded metal lath

This was then covered in ordinary undercoat plaster

really? a gypsym product? I wouldn't recommend this.

[Nev Grady]

Re: UK 34" rounded square Oven Progress.

Yeh! The weather in the UK has been really crap for the past few weeks! Especially where I live in the northwest. Incessant heavy rain. No shortage of water here!

Is 50-75mm of dry vermiculite sufficient? Even if you do manage to form a render shell can you be sure that the dry vermiculite you pour in is spread evenly inside it?. Why not use all fibre insulation?

I first covered my dome (1 metre internal dia.) with 5 layers of heavy duty aluminium foil. This helps with any cracks which may develop and also reflects heat back into the oven. I then put on two layers of 25mm INSULFRAX. One roll was sufficient. This stuff is good up to approx 1250 Celsius. On top of that went two layers of 50mm thick ROCKSILK FLEXIBLE mineral insulation bought from B&Q (UK's Home Depot equivalent). One pack was enough. This is good up to 800 Celsius.

From the same place I bought 3 large sheets of plasterer's mesh which was cut to shape and wired together. This was then covered in ordinary undercoat plaster about 20-25mm thick followed by about 25mm of waterproof cement render. 2-3 days work should get you to the point of being ready for the waterproof render. The photo shows the insulation, mesh and oven opening not quite finished.

Works a treat. The oven heats up to temperature in about 1 hour, and with an insulated door in place it holds the heat extremely well.

[Frances]

Re: UK 34" rounded square Oven Progress.

I had the exact same problem... let me see if I can find the pics. Ok, they're right at the beginning of this thread:

http://www.fornobravo.com/forum/f9/pompeii-oven-switzerland-saga-continues-2991.html

I hope you can tell what's what, it was kind of difficult to take pics of it all. Basically I built a structure of rebar over the oven, and covered it with chicken wire and the carpet underlay bit by bit, filling with vermiculite as I went

Wiley did something similar, only 100 times more perfect:

http://www.fornobravo.com/forum/43/steel-dome-oven-3717-7.html

Actually I'd follow his version if I were you, it really is a lot nicer!

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

I really need some help, I have done nothing for a few weeks now, the weather has been terrible or I have been at work on the nice days, so I have not even had time to use the oven let alone finish the dome! very disappointing!

However, I have next week of work and intend to get a full day in finishing the oven(more fearing winter than needing to finish it). So, my plan is to finish the insulation of the dome and the render finish. What I would like to do is create a render dome and then pour in dry vermiculit to insulate rather than use the compromising vermiculit conrete.

The issue is, how to create a render shell! chicken wire, obviously comes into the equation, but how to hold it 2-3 inches away from the dome. I was thinking maybe a cardboard shell that could be carefully burnt out. Or possibly a fibre glass shell with render on-top(but would heat damage it?) as I have a roll of galls fibre that is looking for a purpose.

OR does someone else have a suggestion that may work?

[Gromit]

Re: UK 34" rounded square Oven Progress.

I really like how you did your dome. It is a lot like some of the Le Panyol ovens with "orange wedge" sections: Le Panyol Model 99 | Masonry Heaters and Wood Fired Ovens - Maine Wood Heat Co.

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

thanks dmun and nev,

to the side sounds like a good ides, I realise that I now need to make a few more cooking tools and a door too!

the oven was still warm 24 hours later, and it rained for the most of last night, with some more good insulation, it will never cool down!

[dmun]

Re: UK 34" rounded square Oven Progress.

Looking good! A hint: if you push your fire to the side, instead of the back, you can see the edge of the pizza exposed to the fire, and quickly see how it's browning up.

[Nev Grady]

Re: UK 34" rounded square Oven Progress.

I know the feeling! That first pizza is the best ever and put's a big smile on your face!

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

Tonight was the big night, I fired the oven up nice and hot, I did do it fairly slowly, as it was the first time, it took 2 hours until we started to cook.
I reckon with a bigger fire rather then I used it would heat up lots qiucker.

So, here are some pic's of the first pizza cooking and the end product! I'm really pleased, it was a long slow road, and at times I got fed up and disheartened with the whole project, but after tonight, I am so pleased I saw it through!

Now the learning of cooking starts, first off, I will keep the fire over the centre of the oven to heat the floor up more, I keep the fire at the back tonight, second, prepare the pizza's on a marble surface or similar, as we made 3 on plates, and they stuck, but they still cooked once sorted!

Last off, I was not keen on the idea of another 2-3 inchs of inculation, but after 2 hours the oven dome was very hot, still able to touch it, but this does represent a massive loss of heat, so I will be further insulating the dome!

Wood fired Pizza ovens rule!!!

[Nev Grady]

Re: UK 34" rounded square Oven Progress.

I agree with dmun, 2 inches of ceramic insulation isn't enough if you want the oven to hold it's heat for 24 hours or more. If you want to fire it up and cook pizzas etc there and then you shouldn't have a problem. If it's pizzas in the evening, bread the following morning and maybe a slow roasted joint for dinner you'll need much more insulation.

I've covered my dome with 5 layers of heavy duty aluminium foil, 2 inches of Insulfrax high density ceramic insulation then 4 inches of high performance mineral (Rocksilk) insulation. With an insulated aluminium box door containing 6 inches of vermiculite inside, the oven temperature after 24 hours, following a pizza session is as high as 190-200C (375-390F).

My advice is put 3 or 4 inches of vermiculite or perlite cement on there before your final render. It will make your oven more versatile.