Medium vs Fine grade Vermiculite?

[dmun]

Re: Medium vs Fine grade Vermiculite?

Just a side note: If you are hiring a mason the labor costs will always dwarf the material costs, making this a pricey project. The cost of a few firebricks is a relatively minor factor, if you are springing for a professional build.

[Tscarborough]

Re: Medium vs Fine grade Vermiculite?

They are rare because they are from old buildings. There are very few brick manufacturers in the US making dry pressed brick, other than for firebrick. There is one local to me, but the brick are of poor quality and are still half the price of firebrick, there is no way I would use them in an oven.

I have a bunch of handmade adobes I want to build an oven with (because I got them free), I have thrown them into bonfires with no ill effects, so they will probably work as well, but the cost is more than firebrick normally.

[aeu99217]

Re: Medium vs Fine grade Vermiculite?

That would explain why they seem to be relatively common here in Glasgow given that many of the buildings were built during empire days. Wilson and co is printed on the bricks and i was told that they used to emport them to oz in the 30s.

[Tscarborough]

Re: Medium vs Fine grade Vermiculite?

Yep, but I bet they are not tearing them down like they used to. They are still knocking down a few in Chicago where most of mine come from, but not like they were 10 years ago.

[Rolaed]

Re: Medium vs Fine grade Vermiculite?

I poured the 4" vermiculite/portland cement mixture today. Strange spongy stuff!! You cant really level it like concrete. A few bumps/waves here and there.

Do I need to put plastic over it or water it periodically? If so, how often.

How long should I wait before laying the firebrick.

Also, is refractory cement the same as fireclay. The place I got the vermiculite from sells refractory cement by the gallon. How many gallons would I need?? It is not cheap!!

[GianniFocaccia]

Re: Medium vs Fine grade Vermiculite?

Refractory cement is different than refractory mortar. As far as refractory mortars go, most FB'ers recommend the dry mix, instead of the wet stuff that comes in tubs and is prohibitively expensive. The first five or six places I called looking for Heatstop 50 didn't carry it anymore so I called the corp office back east. I was quoted $85 for a 50lb bag (without shipping) by a lady whose nasty tone of voice told me she had better things to do than talk to me. I am now building my oven with homebrew mortar, but you can always order an 'authentic' refractory mortar from James here on the FB site.

[dmun]

Re: Medium vs Fine grade Vermiculite?

Refractory cement is not sold by the gallon. It's a powder, and it's sold by the pound. You probably don't want it anyway: calcium aluminate mortars are difficult to work with. What your vendor probably has is pre-mixed wet mortar in tubs. It's not cheap, and it has problems for our application: it's heat set, it's not water resistant, and it's designed for minimal joints, unlike the wedges between tilted bricks that we need to build. When you lay it on thick, it has real difficulties drying.

Besides, why pay refractory material prices for water? Have you looked into the homebrew mortar? It's inexpensive, and builders have had good results with it.

If your refractory dealer doesn't know what fireclay is, I'd wonder what else he doesn't know. Southeast Michigan is the mecca and medina of American industry. A google maps search for "refractory near canton mi" returned 188 results. This is to say nothing of the brickyards and mason suppliers that will sell fireclay for half the price.

As to your vermiculite question: you can build on it as soon as it is solidified. One of our builders just set down his floor in the wet vermicrete: no waiting at all. Also, covering it and building onward is as good a way of keeping it damp for a week an any.

[Rolaed]

Re: Medium vs Fine grade Vermiculite?

Refractory cement is different than refractory mortar. As far as refractory mortars go, most FB'ers recommend the dry mix, instead of the wet stuff that comes in tubs and is prohibitively expensive. The first five or six places I called looking for Heatstop 50 didn't carry it anymore so I called the corp office back east. I was quoted $85 for a 50lb bag (without shipping) by a lady whose nasty tone of voice told me she had better things to do than talk to me. I am now building my oven with homebrew mortar, but you can always order an 'authentic' refractory mortar from James here on the FB site.

The stuff at the builders supply place is called HeatStop and it is a powder. They charge $14/gallon. Is this the stuff to use? How many gallon tubs would I need to buy?

[Tscarborough]

Re: Medium vs Fine grade Vermiculite?

Heatstop is in the 40-60 dollar range for a 1 gallon tub of dry. If they are selling it for 14 bucks, something is wrong.

[dmun]

Re: Medium vs Fine grade Vermiculite?

Heatstop is in the 40-60 dollar range for a 1 gallon tub of dry. If they are selling it for 14 bucks, something is wrong.

Heatstop comes (or did when I was buying it) in a ten pound plastic tub, and a 50 pound bag, where it's called heatstop50. It goes from a little more to a little less than a buck a pound, so fourteen dollars for a bucket is about right. The fifty pound bag is in the fifty dollar range.

It will take three to four fifty pound bags of heatstop if you aren't cutting bricks to angles. I built my 36 inch thin dome with one bag, but I cut every joint.

[Tscarborough]

Re: Medium vs Fine grade Vermiculite?

You are right, I got cornfused. I sell the bucket for 22.50 and the 55# bag for $55.00.

[Krayon]

Re: Medium vs Fine grade Vermiculite?

another question regarding medium/fine - how can you estimate how much perlite should you use in making the insulating percrete? let's say a 4' X 4' X 4". Any different from estimating normal concrete?

[Tscarborough]

Re: Medium vs Fine grade Vermiculite?

Ignore the amount of cement, just use the perlite cubic feet.

In your example, you need 5.34 cubic feet of perlite, and at 1-5 ratio, one bag of portland cement (a 94# portland=1 CuFt).

[Krayon]

Re: Medium vs Fine grade Vermiculite?

Ignore the amount of cement, just use the perlite cubic feet.

In your example, you need 5.34 cubic feet of perlite, and at 1-5 ratio, one bag of portland cement (a 94# portland=1 CuFt).

thanks got it. makes things easier. now i just gotta find suppliers round here in Manila, planning on medium grade for my slab and fine over my dome, if the cost isnt too prohibitive.

thanks, Ill probably be hanging around here more often from now.

[Rolaed]

Re: Medium vs Fine grade Vermiculite?

We did the dome today. It is drying now. Question about the exterior top of the dome, should I fill it in with the same fireclay/sand/lime/cement mix OR can I get by with just sand adn cement as my mason suggested?