Building an oven in Hawaii

[RTflorida]

Re: Building an oven in Hawaii

Paul, I'm not an expert on castables but I will give you my take from researching products on Harbison Walkers site (hwr.com).

General castables (with little or no insulation value) tend to have a higher content of alumina than silica as well as lime. These castables have a 55% - 90% alumina content and a lime content of around 2%-6%. The Mizzou Castable that you have appears to be a medium duty standard castable that is not intended to have any insulating value.
Insulating castables have a silica content greater than the alumina content - about the same 55% +; with a lime content of 6% - 12%.

The Harbison Walker site lists your Mizzou Castable as a standard castable, not in the insulating category. You might want to check out the site, very informative with all of the products listed by category and trade names with data sheets - for dozens of refractory products.

RT

[sacco]

Re: Building an oven in Hawaii

RT thank you for your abundant and thoughtful advice and time. Aloha Paul

[RTflorida]

Re: Building an oven in Hawaii

You are welcome...thats why we are all here - to help each other build the best oven possible within our means. Good luck with the rest of your build.

RT

[sacco]

Re: Building an oven in Hawaii

RT: I ordered the ceramic board from FB and it shipped today. Do I just lay the brick, oven floor, on the board? Thanks Paul

[RTflorida]

Re: Building an oven in Hawaii

That should do it. The board provides the flattest surface possible for the hearth bricks, which makes laying the bricks a snap. With any luck you have bricks that are uniform in thickness and high spots will be minimal. The herringbone pattern seems to be the best choice for you brick pattern - if you should have a high edge on any of the bricks. The diagonal herringbone keeps your peel from catching squarely on a high edge, reducing the possibility of a big chip in a brick.
If you do have any high spots after you set the bricks, you have a couple of choices to level them - a little dry fireclay as a bed on top of the board (under the bricks) OR the belt sander method which many of us have used with great success. Take a 40 or 60 grit belt and sand down the high spots ( I then used a medium to smooth even further). No need to sand the entire hearth, just the high spots. Hope this helps.

How about posting some pics of your progress? The wild bunch on this forum LOVE photos.

RT

[sacco]

Re: Building an oven in Hawaii

RT Thank you again. It helps very much. My wife has been taking pictures and I will try to post them. Aloha Paul

[sacco]

Re: Building an oven in Hawaii

I am using the Kaowool blanket to insulate the oven and want to cover that with concrete. Would I need to use refractory cement? I am thinking that the blanket would not let the heat get to the cement so I wouldn't need refractory cement. Any comments would be much appreciated. Paul

[egalecki]

Re: Building an oven in Hawaii

No, Paul, you don't have to use refractory concrete. I used vermiculite concrete on the outside of my blanket just for overkill insulation- but you can use regular, no problem. Do you mean concrete or do you mean mortar, by the way?

[sacco]

Re: Building an oven in Hawaii

Thank you Elizabeth: I was thinking concrete but can I use mortar?

[egalecki]

Re: Building an oven in Hawaii

I believe that others have used type N or S on the outside of the blanket. I used type S on the outside of my vermicrete as the first two layers of my stucco. It worked fine.

[sacco]

Re: Building an oven in Hawaii

Help! I finished the oven, cured it and lit the first wood fire. Lot of smoke. What is the best wood, that might be available in Hawaii. I used mango from a tree I cut 6 months ago and I am not sure I should use mango wood or such young would. All comments appreciated. Aloha Paul

[Jed]

Re: Building an oven in Hawaii

Paul,

Use dry - well cured wood.

The variety is less important.

The harder the wood, the more BTU's per volume, but one of the beauties of the oven is that it will get hot with any wood that will burn. And dry - cured wood burns well.

Past that, folks will have preferences. Some wood will do 'this' job a bit better or 'that' job a bit better. I seam to remember one of the guys was happy with the way mango worked in his oven... (Can't report from personal experience as we don't get much Mango here in the high desert). Generally hard wood is better than soft wood, and generally it will take more than six months to cure wood through. If your fire was smoky, even after it had been burning for awhile, you probably had green, or uncured wood.

Your oven will take awhile to drive all of the moisture out of the concrete. I think as a rule plan on about a dozen good fires in the oven before you start evaluating if the thing 'holds heat well'.

But at the end of the day, heat that baby up with any wood that will burn! (Try to avoid pallets or any wood from an industrial application - some are treated with chemicals we don't want in our food...)

And report the results!

Good luck with it..

JED

[Modthyrth]

Re: Building an oven in Hawaii

Mango contains the same chemical in poison ivy that causes such an awful skin reaction. I'd be wary of burning the wood. You might be lucky and not be affected by the urushiol in both, but If you were ever to have guests over for pizza, there's a good chance one of them would be highly sensitive. Me, I can run through a field of poison ivy (and have, many times) without any reaction, but for those it affects, it's miserable.

[Jed]

Re: Building an oven in Hawaii

Mango contains the same chemical in poison ivy that causes such an awful skin reaction. I'd be wary of burning the wood. You might be lucky and not be affected by the urushiol in both, but If you were ever to have guests over for pizza, there's a good chance one of them would be highly sensitive. Me, I can run through a field of poison ivy (and have, many times) without any reaction, but for those it affects, it's miserable.

Nikki,


Good information.. new to me and worth reporting!

JED

[mabrunetti]

Re: Building an oven in Hawaii

I am on the Big Island. Did you find everything you needed to build your oven? Could you let me know where you got it?