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karl 07-18-2008 03:01 PM

Rockwool for insulation

I find it very difficult to get access to some of the materials recommended for insulation of the oven (ceramic fibres etc.). I did come across a 100L bag of perlite. But now I am a bit worried that this material could drizzle into the small cracks which necessarily must form.
Why could I not just use rockwool for insulation? It is claimed to withstand more than 1000 C and after some discussions on this forum I am convinced that I will never reach more than between 600 - 800 C in my oven. Any comments or advice on this thought?

regards from Karl

christo 07-18-2008 03:27 PM

Re: Rockwool for insulation
I did a wiki search on rock wool and found the name represents a wide varity of products.

One item I did note:

"All European produced rock (stone)wool and glass wool is bio soluble". This would imply that it might be affected by water" - so becareful.

Also - be careful cause you can't trust everything you hear on the internet.;)


ihughes 07-18-2008 04:00 PM

Re: Rockwool for insulation
Rockwool is oftem stocked by the same suppliers as ceramic fibre blankets, here in Australia anyway.

Have you tried talking to industrial insulation specialists. Often I've found going to the high-end of users to find what they use and where they get it from and work back to the supplier can be effective.

dmun 07-18-2008 04:04 PM

Re: Rockwool for insulation
"Bio-soluble" in this context means that the fibers will dissolve in your lungs, so they are a lesser silicosis hazard. Wear the respirator anyway.

david s 07-18-2008 08:19 PM

Re: Rockwool for insulation
For my first oven I used fibreglass insulating bats (which I think is also refered to as rockwool) It did the job ok and on inspecting it when I removed a floor firebrick, the fiberglass bat under the brick appeared not to have deteriorated in any way. Trouble I found withe the fiberglass on the outside of the dome was that it compressed very easily and it then made the job of chickenwire over it very difficult. I now prefer vermiculite/cement 10:1 which goes firm when set.

berryst 07-19-2008 05:17 AM

Re: Rockwool for insulation
Hi Karl
Purolite is mixed 5 to one with concrete. I am using it and have never heard of any spilling through the cracks. I believe that this a standard tried and true application and you won't have problems. Incidentally my son will be in Bergen Noway on the 20th...a good-guy collage kid,

christo 07-19-2008 05:30 AM

Re: Rockwool for insulation
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Good day!

If you are going with an enclosure vs igloo, you can use it loose as well and the joints in your enclosure must be pretty close to keep from spilling out. (Please don't ask me how I know!)


karl 07-19-2008 02:18 PM

Re: Rockwool for insulation
Thanks everybody for replying,

I am planning to do an enclosure rather than the igloo. Even though the igloo principle may sound very adabtable to our climate ! The rain and the snow ower here call for a proper enclosure and I was worried about using loose perlite (penetrating into cracks,- and now seeing Christo's experience ...). I agree that using it with cement should be better. But I thought that the job of mixing and "smearing (?)" it all over the oven could all be avoided by just using rockwool (I do not know the US brand name but it sound very much like the type David s was using. It is sold both as hard mats and in softer and thicker sheets).
I haven't heard anything in your comments that actually should be a "show-stopper" in that respect?!

regards from Karl

PS Laborer,-hope your son have a good time in Bergen. Just heard that Metallica had a concert there yesterday. He missed them with a couple of days. DS.

toddj 08-12-2008 10:26 PM

Re: Rockwool for insulation
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I used Rockwool ( stonewool ) 4" thick slabs when I built my powdercoat oven and I can run it up to 1000f and the metal oven is cool to the touch on the outside. I cut it to fit with an electric meat carving knife.

dmun 08-13-2008 07:06 AM

Re: Rockwool for insulation
One of the problems with insulation technology is that there is no standard vocabulary. What might be "fiberglass" in one place, might be "mineral wool" in another. After all, silica is a mineral. This doesn't mean that every type of insulation is suitable to every application. One of our members had a cracking problem when his insulation board turned out to lack water resistance, and squished when it got damp.

If you are using untested materials, you need to read material data sheets, and talk to applications engineers with the manufacturers. If those things are as difficult for you as they are for me, you need to follow the tried and true standard practice.

That said, we like to hear about experiments, and what different materials are used in different countries.

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