Homemade Perlite Board.. and Door

[asclepius]

I am about to begin constructing my oven door, and so I was wondering if anyone had used perlite or vermiculite board in their door before, and if so, did you make it at home?

I am having a hard time bringing myself around to purchasing a ceramic fire board online due to prices and shipping since I have about 40 square feet of fire blanket left. Therefore, my current plan is..

Having the outside of the door made out of hardwood. Then i would put 3 or 4 layers of my extra 1" ceramic fire blanket on top of that (and smash it down a little). Next I would put my homemade perlite board which will be around 1.5". Then those will be bolted together and I will have that covered by either steer or aluminum. Any thoughts?

[cobblerdave]

Re: Homemade Perlite Board.. and Door

Gudday

One thing to keep in mind ( as a rabid backyard "over engineer er" myself) is the weight of the finished product. Concider weighing all the parts before building otherwise you could end up with a wrist breaker.

Regards Dave

[Les]

Re: Homemade Perlite Board.. and Door

As Dave mentioned, I would keep the weight in mind. I would be more concerned that the ceramic fiber was sealed. You don't want the stuff in your food.

[asclepius]

Re: Homemade Perlite Board.. and Door

Yes, my priority is to make sure the ceramic is sealed in. I am construction an internal box of aluminum that will hold the ceramic blanket in it .

My concern was the weight in regard to my own board. I do not want to use portland/perlite for that reason, but I have searched all over the internet looking for another resin that I could use to bind the perlite together to make a board but so far no luck.

[Laku]

Re: Homemade Perlite Board.. and Door

I would use stainless steel if you can instead of aluminium, which is about 15 times as good heat conductor as ssteel.

[Les]

Re: Homemade Perlite Board.. and Door

looking for another resin that I could use to bind the perlite together to make a board but so far no luck.

I just poured loose vermiculite into my door. It works pretty well. It does conduct some heat but I am still able to cook on day three.

[Faith In Virginia]

Re: Homemade Perlite Board.. and Door

I used galvanized steel and packed 3" of vermiculite / Portland as the core. It's a bit heavy but makes a good seal. I get some heat loss through but not enough to worry about.

[asclepius]

Re: Homemade Perlite Board.. and Door

I thought galvanized steel was bad due to the zinc burnoff??

[asclepius]

Re: Homemade Perlite Board.. and Door

So I have been researching some, and I think I am going to try a different approach to a door. I play to mix plaster of paris with perlite, then on the outside of the door i will have a wooden exterior. It will all be encased in steel which will in turn be riveted to the door. I also plan to put two layers of 1 inch thick ceramic blanket in front of the plaster of paris. Overall I am hoping for a thickness of 5 inches.

My question is, has anyone used plaster of paris for a door? Mixed with perlite?

[dmun]

Re: Homemade Perlite Board.. and Door

Plaster isn't waterproof. I'd stay away from gypsum products in any potentially wet area. The first rain will reduce your insulation to a crumbly mess. If you're encasing in metal, why not use loose vermiculite? Less weight, less problems.

[david s]

Re: Homemade Perlite Board.. and Door

The problem with Plaster of Paris is that it holds moisture really well. It will still hold together when wet but if there is a substantial amount it will turn to steam really suddenly and blow it apart. Wet plaster takes about a week to dry out.

[fornax hominus]

Re: Homemade Perlite Board.. and Door

I built mine just like yours, 1'' of ceramic fibre, 2 1/2 '' of vermicrete with aluminum sheet surround bolted through to a wood exterior .. 2 years on [100+ heats] , all is well . I have staining around the bolt heads as they are the thermal conduit ... they sure get hot! but nothing else.. it is a bit heavy but I put 2 large wooden handles on so you can get a balanced grip.
I did attach a heavy woodstove gasket around the perimeter to finish the seal ..gasket glue would not hold on the wood, so I ended up holding it in place with construction staples.
happy cooking!
tim

[setman1]

Re: Homemade Perlite Board.. and Door

I'm going to cast a vermiculite/high heat morter board today with hardware cloth inside to stiffen. 1" thick to be sandwiched between two identically-sized steel door plates (one with handles, of course). I don't plan to enclose the edges with metal unless the the board starts chipping and falling apart at the edges with use.

[david s]

Re: Homemade Perlite Board.. and Door

The big problem when making your own panel is that to make it strong enough you have to use around 50% vermiculite or perlite to refractory mortar. Anything greater than 50% will be far too weak IMO. I use Stainless steel needle reinforcing to help strengthen the panel, but these also have the problem of conducting heat, so while they make it stronger they reduce the insulating capacity of the panel. I also fire the insulating panel to 1000 C to increase its strength. Reducing the vermiculite or perlite proportion in an effort to get acceptable strength starts to make the panel fairly heavy. If only 1" thick then it may not be thick enough to prevent the heat from soaking through the panel. By having steel plates on each side of the panel you will be heating it up more because the steel is so conductive. Use the smallest gauge bolts to join the steel plates together because the heat will conduct easily through them.

[setman1]

Re: Homemade Perlite Board.. and Door

Ha. My first attempt at a vermiculite board was a failure--- not enough morter in the mix and it's crumbly. I'll get to the metal shop today and get them going on the steel plate and handle pieces before I try again. I may be barking up the wrong tree with this but my thinking is that any insulation is better than a single steel plate and ceramic board is hard to get and way expensive.