#11  
Old 06-25-2007, 06:24 PM
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Location: Adelaide, South Australia
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Damon,
it sounds like you are back on track.
I didn't overlap my blanket, simply butted it close together, mainly to ensure a nice smooth semi spherical dome.
You can use a second layer of chicken wire and if putting insulation cement (vermiculite cement) over the blanket. you will need to do this if you want it to stay in place. Once you get the first layer on, it is much easier to apply the second and subsequent layers. You won't need to use anymore wire after the insulation layers are on. The final water proofing plaster/render/stucco layer will bond beatifully to the vermiculite layers and water proof it or as a good base for tiling of painting as required.
Phone Fiona at Thermal Ceramics
10-14 Toogood Avenue
Beverley S.A. 5009 Australia
Tel: +61 (8) 8243 5300
she will organise whatever you need. A very knowledgable lady and rather pleasant on the eye as well.

Neill
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  #12  
Old 06-25-2007, 07:33 PM
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Default Re: Dome stayed up this time!

Oz and all,

Had a thought. We've been dealing with the Portland/vermic mixture for so long that maybe we should step back a bit and consider. Straight Portland does not have a lot of inherent stick to it and is quite rigid. Let's at least consider using a vermic/Type S or vermic/Type N mixture. Type N is good for vertical surfaces and will provide the needed stick, so will Type S, but less so. In an insulating layer, rigidity is less of an issue than stickiness.

Addtional thoughts? Uno?

Jim
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  #13  
Old 06-25-2007, 08:06 PM
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Default Re: Dome stayed up this time!

Jim, I took your advice and used the Type N over my perlcrete insulation before doing my mosaic tile....your 110% correct on its sticky nature. I've used Type S many times but this was the first for the N....very good adhesion on vertical surfaces. Good advice.

Never mentioned this before, but I actually ran out of portland when pouring my vermiculete hearth slab. I had 1 1/2 bags of Type S leftover from another project and used it to finish the insulating slab (glad I had it, didn't want to risk wasting 45 minutes running to HD in the middle of the pour)....other than being a slightly different color grey, you could not tell the difference from the portland area.

RT
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  #14  
Old 06-26-2007, 02:50 AM
Peasant
 
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Default Re: Dome stayed up this time!

Good advice Neill and Damon. I reckon I better check Google Earth to see just how many domes are appearing in backyards around Adelaide.

The discussion on cement beyond Portland is beyond my realm of interest although I have supplies of both Portland and White cement (Brighton lite) and have wondered if they have the same qualities under heat and as an outside render.

Cheers
Steve
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  #15  
Old 06-26-2007, 03:23 PM
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Steve,
my understanding of Brighton lite cement is the same as portland cement only that is an off white cement rather than grey.
There are two basic types of cement, general purpose and Blended cement. The latter has a percentage (around 25%) of flyash in it to 'extend' it but also improves the workability of the mix and improves strength over time.
Brighton lite is a specially manufactured Off White Portland cement that has revolutionised the development of architectural concrete.
Neill
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  #16  
Old 06-26-2007, 06:49 PM
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Default Re: Dome stayed up this time!

Just an added bit with you guys about insulation. There is a product here in the US for ceramic fiber that makes it more rigid. It sprays on and you can shape the fiber, then once it sets it holds its shape. Don;t know if it has a practical use. Further on this issue I have to say that my most major mistakes in constructing my oven were to not give adequate respect to the expansion of the oven and by not insulating it enough. It is a good oven but the enclosure has cracks that have stabilized with time but I don't get a stable heat curve do to the lack of enough insulation.
Best
Dutch
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  #17  
Old 06-26-2007, 07:23 PM
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Default Re: Dome stayed up this time!

thanks Dutch .....I'm thinking of firing my oven this Sat. as a check before I do the final render(stucco).
I think I have the blanket & perlite on correctly (after reading all the great advice on here) but this firing will allow me to check if there are any parts of the outer dome where it could be "leaking" heat.

Kiss4me.....doesn't it suck dealing with all the rain and cold at the moment? - I suppose its good for cement to cure though.
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  #18  
Old 06-26-2007, 07:24 PM
Il Pizzaiolo
 
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Default Re: Dome stayed up this time!

Dutch,
good point and exactly why I used 2" blanket on my oven. After talking with a local refractory specialist (who has built several precast ovens)
I decided the extra $$ spent on a thicker blanket would be a big benefit.
His thinking was the thicker blanket would absorb more thermal expansion of the dome, resulting in less potential for cracking of the ridgid exterior of the dome. Since my plan all along was to finish with mosaic tile, I certainly wanted to minimize the chance of exterior cracks........this would be of importance to those finishing in stucco as well.
I topped the 2" blanket with 3" of perlite concrete. Not a single dome crack and I have had the inside top of the dome over 1100 degrees. No rise in temp on the exterior....Good for my tile or would be for a stucco finish.

I think many of us have beat this horse to death, but it really can't be stressed enough. Insulate your oven until you either run out of money or your supplier runs out of insulating material. MORE MORE MORE
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  #19  
Old 06-27-2007, 03:37 AM
Peasant
 
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Default Re: Dome stayed up this time!

Yeah Damon, weather at the moment is not ideal for working outside. There is something bleak about working with wet cement on a cold damp day. Still we have seen off the shortest day and those in the northern hemisphere can get their share of the cold soon (by th eeather reports lots of areas could do with it!)

Point emphasised by Dutch about the importance of getting the insulation right is taken. Amazed to read that others ovens have 'leaked' after all these layers. I could put this down to poor workmanship, but this would be a bit rich.

Steve
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  #20  
Old 07-08-2007, 03:35 AM
Peasant
 
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Default Further progress - chimney

Quick update.

Found some time today to work on chimney. See photos attached. I hope it draws well as the vertical difference between dome opening and chimney opening base is greater than I was hoping.

Cheers Steve
Attached Thumbnails
Dome stayed up this time!-chimney-progress2.jpg   Dome stayed up this time!-chimn.jpg   Dome stayed up this time!-chimney-progress.jpg  

Last edited by KISS4me; 07-08-2007 at 03:39 AM. Reason: removing duplicate photo
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