Super Isol Questions

[Ted Rosenberg]

When using the super isol boards do you set the firebricks directly on top of the board? Do you use a layer of sand or any mortar?

[jwnorris]

I am in the process of building a Casa 110. I found that the SuperIsol sucks the moisture right out of even a soupy mortor. Ultimately I placed the floor directly on the SuperIsol, figureing that in anything below a major earthquake [afterall I am in SoCal] will not move that much weight.

[Alan]

I, too found that super isol sucked moisture from refractory mortar. However, a film of mortar left to cure on a scarp of the material is nonetheless really stuck. I would guess that you could trowel on a thin layer of mortar, let it cure, and then you'd have an impervious surface that would give you a reasonable working time with an adhesive layer for the hearth.

Because my insulating board layer was nice and flat, I glued my floor down with a refractory adhesive.

[Ted Rosenberg]

To mortar or not to mortar

I appreciate the responses posted so far; but I am thinking of just placing the bricks herringbone style on the super isol without mortar. Is there any down side? James or some other Guru, what is the best way? I plan on doing this today and want to do it right. Thanks

[dmun]

bricks on board

I just laid my bricks down on my insulating board. It was odd feeling the bricks creek underfoot when I was building up my dome, but they didn't shift, and now that the dome is up, I'm not walking on it any more. There was some refractory slurry that went in between my bricks when I cleaned it, and I think firmed it up some too. Of course with a casa 110 you'll have a lot fewer joints to clean than I did.

Herringbone brick? Doesn't the casa come with that neat four sector refractory floor?

[christo]

http://www.fornobravo.com/forum/showthread.php?t=635

This might help.

The comments that the super iso will really suck up water trouble me - I wonder how this affects laying the floor - I expect one has to work fast or in sections as the water leaving will make it stiff rather quickly.

The Firebricks I bought look really flat and sharp, when but when I place them edge to edge on dry Iso board there are slight height differences.

Based on the general inputs from the list: I will use the fireclay sand mixture, lay the floor in a herringbone pattern, and get the best level I can. I will then let it dry before putting load on the floor (like crawling around or kneeling on it). I'll order a pizza peel from James and grind down any brick edges that catch on the peel.

Christo

[james]

Differnt floor have different needs

Ted,
Good question. I should make this more clear. Different oven floors have different requirements. The Pompeii Oven with a brick floor can either be set on a bed of sand, or even better, an underfloor made from fireclay, sand and a little water. The bricks fit snugly against each other, holding everything together, and the clay/sand underfloor lets you tap the bricks down to be level.

There is a recipe here:

http://fornobravo.com/pompeii_oven/cooking_surface.html

The Casa and Premio floors are cast with a smooth finish from Alto Refrattario Aluminoso and are designed to be set with refractory mortar. That way the pie shaped pieces can be set level and the seams can be smoothly filled. That said, folks can put those floor pieces in sand and not worry about the seam, and they work the same way.

The Artigiano floor is made from Cotto Refrattario, a more brick-like refractory material that is cast, then cut. The pie-shaped floor pieces fit together tightly, like brick, so that floor is set on sand, or the sand/clay mix. The seams line up tightly.

This should help.
James

[Alf]

A little tip for setting an ovens floor especially if you haven?t done it before or are worried about the mortar ?going off? before you are satisfied with the finished result and level of the floor.

Mix the mortar as per recipe but dry i.e. no water. Set up the ovens floor on the dry mortar mix and get it level. Once you are satisfied with the floor use a watering can with a rose and sprinkle the firebrick / floor with water. The water will percolate down into the dry mortar and set it. Give the mortar a couple of days to set and the start the rest of the oven building

Alf

[dmun]

Mix the mortar as per recipe but dry i.e. no water. Set up the ovens floor on the dry mortar mix and get it level. Once you are satisfied with the floor use a watering can with a rose and sprinkle the firebrick / floor with water. The water will percolate down into the dry mortar and set it. Give the mortar a couple of days to set and the start the rest of the oven building.

Isn't that clever? It would work for the sand/fireclay method too, which, after all just turns into a dried mud, not a concrete product.

Years ago, before a hurricane, the township here built up a retaining wall by the river by filling burlap sacks with dry concrete mix. The rain did the work of hydrating the concrete, and years later, the sacks long since having rotted away, it's still a sound concrete retaining wall.

[dmun]

grinding high spots

I'll order a pizza peel from James and grind down any brick edges that catch on the peel.

Before you get out your angle grinder, just rub the high spots with the cut edge of a fire brick: This will knock off the high spot without gouging. Go for the minimalist treatment. The cut or abraded edge of a brick is considerably softer than the factory edge.