Rock wool as insulator?

[Lburou]

from Wikipedia Mineral wool, mineral fibres or man-made mineral fibres are fibres made from natural or synthetic minerals or metal oxides. The latter term is generally used to refer solely to synthetic materials including fibreglass, ceramic fibres and rock or stone wool. Industrial applications of mineral wool include thermal insulation, filtration, soundproofing, and germination of seedlings.

Rock wool is made from rocks here in Texas, so should be plentiful and cheap. Has anyone used this material to insulate above their dome? I would consider it under a roof above the dome.

[Lburou]

see This thread (Mineral Wool/RockWool) for more

[SCChris]

I used 2 inch boards as the insulator directly in contact with the dome. As I have stated in other places, the board product isn't as flexable as I would have liked. I was looking for the bats I used in the 70s, these were more like fiberglass bats. My opinion is that cost wise the ideal would be to find rockwool blankets, if they exist. I'm envious of the ceramic blanket, these look so taylored when in place compaired to the rockwool boards. In an enclosure, I don't know that Ceramic Fiber or Stonewool, rockwool, will really perform very different if care is taken when placing the insulation. I wrapped and tucked scraps in open spaces and outside of the direct contact with the dome I placed Fiberglass in the enclosure corners, for support of the stonewool and for convenience sake. After getting these tight and tidy I poured vermiculite over the top of this and filled out the enclosure. I'm happy with how things turned out. I think I loose more through the floor and slab than through the dome. On top of the 5" inch slab I have 2" inches of rigid ceramic insulation on top and then the 2.5" firebrick and dome laying on this insulation.

Chris

[Lburou]

Sounds like you attended to the little details. Can you tell us how long it takes to heat your oven to pizza cooking temperature and how long it stays hot?

[SCChris]

Heating an oven is a bit variable, how big was the fire and how fast it got there.
How log it stays hot is a function of how log the burn was and how saturated the oven gets. Most times I go slower in the beginning and build after the first half hour or so, but the dome usually goes white in about 1.5 hours. I can never tell just when company is going to be ready so most burns go for several hours, 3 to 5.

My oven is perceptably above ambient at 5 days. Typically I run about 725 +- on the deck when I close the door. The next day I drop about 150F or so, say 475 - 500, the following day about 350 or so and about 270 or so on the forth night. So cooking goes something like this.

1st night Pizza
2nd - High heat Roast - eg. lamb rib roast, or boneless leg of lamb and roast veggies
3rd - Hash of the previous night
4th day long Sholder Roast of pork -
Once the food is out the next starter load of wood goes in to dry.

Chris

[Lburou]

Originally Posted by SCChris

Heating an oven is a bit variable, how big was the fire and how fast it got there.
How log it stays hot is a function of how log the burn was and how saturated the oven gets. Most times I go slower in the beginning and build after the first half hour or so, but the dome usually goes white in about 1.5 hours. I can never tell just when company is going to be ready so most burns go for several hours, 3 to 5.

My oven is perceptably above ambient at 5 days. Typically I run about 725 +- on the deck when I close the door. The next day I drop about 150F or so, say 475 - 500, the following day about 350 or so and about 270 or so on the forth night. So cooking goes something like this.

1st night Pizza
2nd - High heat Roast - eg. lamb chops or boneless leg of lamb and roast veggies
3rd - Hash of the previous night
4th day long Sholder Roast of pork -
Once the food is out the next starter load of wood goes in to dry.

Chris

Thanks Chris for a simple explanation describing your heating curve....Very useful for this newbie

[SCChris]

Somehow I got lamb chops down where I meant to say "lamb rib roast". A lamb loin roast is also a great choice for night 2. heat a cast iron skillet in the oven, season the little beasty and drop it in the skillet. My choice is rare to medium rare.

Chris

[Lburou]

Originally Posted by SCChris

Somehow I got lamb chops down where I meant to say "lamb rib roast". A lamb loin roast is also a great choice for night 2. heat a cast iron skillet in the oven, season the little beasty and drop it in the skillet. My choice is rare to medium rare.

Chris

Even so, your post has as much information in it as an announcer reading the small print at the end of a commercial, thanks for taking the time

I'd like to know more about the details of your oven....Did you build extra mass to keepthe heat that long? What kind of floor and floor insulation did you use?

[SCChris]

Lburou,
I didn't add any additional mass to my oven than is indicated in the standard FB plans. The insulation on the other hand, I did take a bit more care.

I used 2" inches of Ceramic Fiber board under the oven and used an enclosure around the dome that I filled with insulation. I think I have 8 to 10 inches of insulation directly over the oven, most of this is stone wool. At the base of the oven is about 4 inches and in the corner of the enclosure is fiberglass attic insulation.

The Fiberglass insulation was convienent and available at lowes but the cost was about what I would have paid for stone wool. The door is made from some of the remaining rigid ceramic board insulation, this could be improved with some "oven door gasket" and I intend to do this at some point.


Chris

[Lburou]

Originally Posted by SCChris

Lburou,
I didn't add any additional mass to my oven than is indicated in the standard FB plans. The insulation on the other hand, I did take a bit more care.

I used 2" inches of Ceramic Fiber board under the oven and used an enclosure around the dome that I filled with insulation. I think I have 8 to 10 inches of insulation directly over the oven, most of this is stone wool. At the base of the oven is about 4 inches and in the corner of the enclosure is fiberglass attic insulation.

The Fiberglass insulation was convienent and available at lowes but the cost was about what I would have paid for stone wool. The door is made from some of the remaining rigid ceramic board insulation, this could be improved with some "oven door gasket" and I intend to do this at some point.


Chris

Thank you Chris! Do I assume correctly that you put the firebrick on the oven floor (larger side down for 2.5 inch thicck floor) and half-bricks for the dome? The extended baking time must be the result of the more than adequate insulating job you have done with the rock wool, yes?