pompeii oven construction began today

[Marcel]

To Jengineer on AbleRefractory insulation; no Group buy

Dear "JE"

You wrote: "Are you looking to set up a group buy?

(M) Nope.

(JE) From the looks of their web pages I would think that these folks are more apt to deal in large bulk quantities.

(M) I tend to agree with your guess.

(JE) Say your local electic power producer that uses coal/gas to fire the furnaces. In the same breath they also point to insulating dentist furnaces.

(JE) From the pdf product sheets their mortors would be overkill for the oven however their blankets could reduce the size of the insulating.

(M) That's waht I hoped to hear from them, possibly accompanied by Tech. Specs. concerning thicknesses of blankets, and area.

(JE) A possible substitute for the Vermin-Cellulite or Pearl-Lite?

(M) You got it. Other postings, such as Paul's bemoaned the amount of fuel he is using. He, for one, is considering adding more insulation on the dome. Others have responded here and suggested options other than Vermiculite &/or pearlite. I want to plan ahead and contributors like Paul et al have already saved me countless hours and dollars by reading of his or her experience.

(JE) You might want to follow this up with one of their sales reps.

(M) Let's see what they write back. We're speaking of such a small amount that if it isn't available locally, I'll date Pearl or Verma.

je - lurking in so-cal

(M) I used to live near Griffith Park. Thanks for your help.

(M) Marcel

[paulages]

overkill is relative to price. if a refractory cement or inulation is rated 2-3 times higher than an oven will ever heat up to, it will still work fine at lower temperatures, and may be more cost effective than buying and mixing your own materials.

[Robert Musa]

with respect to the fuel issue, for what its worth, i too have the perception that i'm using an enormous amount of fuel. last year during the "pizza oven season" we went thru well over a cord of almond using the oven 2 and 3 times per week. and... my oven is really well insulated. 900 degrees inside and cool to just warm to the touch on the outside.

i'm tending towards the following conclusions:

1. heating the oven to the desired temp is like filling a can with a small hole in the bottom. that is; its better to get it to a state of "full" by pouring in as much as heat as fast as you can as opposed to slowly feeding the oven heat. i think i used too much fuel last year because i built (and then fed) medium sized fires while wating for the dome to heat up, when instead i should have built the type of fire that melts your eyeballs right out of their sockets as you approach the dome. in fact, my kids are much better fire builders because in their opinion no fire could possibly be big enough.

2. the type of wood really matters for taste. i use my "trash wood" like pine and yard trimmings to get the fire started and then switch to the almond for taste.

[paulages]

i agree with your "can" analogy. i build the biggest fire i can as quickly as i can get it big, without ablsolutely spilling flames straight out the front. i burn it like this until everything is white hot, then move the fire to the side and cook.

madrone is working very well for me for cooking. all of the softwood i have pops too much, even though it is very well seasoned, so i use it for firestarting. madrone is supposed to burn really hot. seems like we have a similar system.

[Alan]

Perhaps your wood consumption situation will improve when you've added additional insulation. The 4.5" thick walls will take longer to heat up than thinner walls but with enough insulation they should stall hot longer as well. If the outside of your present insluation feels significantly hot, then you're losing heat and need more insulation.

The other area of loss is of course the opening. But the main source of draft in along the floor is the air needed to feed the fire itself, and there should be a net gain.

[paulages]

i do indeed have more insulating to do, but my walls don't get very hot right now. (120deg or so at the top) still, i'm sure the extra insulation will help.

[PizzaMan]

Dry the oven with small fires

Alan Scott, the bread oven guru, is very clear about the need to slowing dry the oven with small fires. He recommends small fires daily, or a heater plugged in 24 hours, for about one week.

I realize that we are using the amount of concrete and accompanying moisture, but I can tell you that my bricks sucked up at least ten gallons of water in the building process, not including the water used for making mortar. I don't expect that to be expelled right away.

My first fire goes in tonight...

Wish me luck; I'm a little worried about cracks.

Michael

aka PizzaMan

[paulages]

good luck!

[james]

I know you know this, but the amount of moisture in either a precast oven or a Pompeii Oven is tiny compared with the Breadbuilder's oven. They are different animals, and the lessons experienced with the Breadbuilder's oven often do not apply -- clearly it is not masterful. You should feel the Italian design come up to heat over a series of seven days, then continue to improve for a while beyond that. The amount of moisture in the bricks or precast oven is minor compared with the 5" of portland cement-based concrete cladding of a bread oven. If you've experienced a Breadbuilder's oven right after installation, you will be pleasantly surprised.

James

[paulages]

mine did seem totally dry, then it dumped rain today really soaking the exterior, even getting water inside. it's totally out of season here in the NW, so i wasn't expecting it...gotta get that roof built!!!

[james]

Ouch. We have a friend with an oven set on a sand hearth (concrete bottom, then sand, then thermal layer -- something I would not advise). The Igloo roof wasn't sealed well, and the sand asborbed a lot of water once, and took over a week of fires to dry out.

James

[janprimus]

insulation matters

I am wondering if any of you use the Kaowool product. They have a 1"X24x25 foot roll you can buy on Ebay for about 55 bucks and it insulates up to 2300 degrees. There is also an insulation rigidizer that will harden the fiber insulation into a hard shell that could possibly be stucco'd over if you were to desire a finish like that... I am just getting into the possibilities here. I would appreciate any and all feedback. FYI I live in northwest Washington.
Thanks.
Chad

[sledge]

I'm also thinking about using the Kaowool product--it's a bit cheaper than the Insulfrax. (It's "good" up to 2300?--although we shouldn't need that right?) There's also the "SAFE" Ceramic Fiber which is even cheaper. Not sure what advantages the more expensive Insulfrax may provide...

Chad, The rigidizer sounds pretty cool! But I've read a few postings on other forums (mainly regarding kilns and foundries) that say the rigidizer makes the blanket brittle and can crack if bumped into. Although that shouldn't be a problem for the oven--provided the dome is enclosed...

[Marcel]

Paul's "Insulcast" Insulation Specs:

# 29


(M) Paul asked, way back in May, if anyone wanted to Google his Insulcast. I found that kinda "kinky" but to each his own. It is reproduced in the Personals, and also below. This forum did not allow any images and I can understand why, but the URL where you can see everything is http://www.pryorgiggey.com/insulati.htm

Here are some Specs. for Insulcast 25:

A temperture rating of 2,500 degrees F.

Mat'l Req'd (pcf) = 87

Cold Crushing Strength ( after 1500 degrees F) = 1,000 - 2,000

Thermal Conductivity (Btu-in/h.ft F) (@1500 degrees F) = 3.2

AL203 = 39.0

(M) No more Googling for me!

Ciao,

Marcel

[paulages]

i keep meaning to relate these specs in practical terms, but for some strange reason, every time i fire up my oven, i seem preoccupied with making pizza and drinking beer.

to really generalize...this castable insulation was really easy to apply. it mixes as easy as quickcrete or any other single substance sack mix, and requires no 'rigidizing'. it seems to insulate rather well, though i should have applied a thicker layer, utilizing chickenwire as a backing. i got mine free, but i believe it's no more expensive than the blankets, and seems to have similar R-values.

and marcel, there is nothing "kinky" about googling. it is not a "lifestyle choice" or a social anomoly. your neighbors are doing it, your co-workers are doing it, and chances are, your children are as well. until we break down these social barriers, we'll never grow as a society.