The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

how to choose fire clay for a bread oven dome

varda's picture
varda

how to choose fire clay for a bread oven dome

Last year I made a dome for my kiko denzer style bread oven using earth I dug up out of new garden areas.   I was able to bake all summer but ultimately there wasn't enough clay content and the dome slowly but surely crumbled.   This year, I would just like to bite the bullet and buy clay.   I found a local clay supplier but they sell dozens of varieties of clay and 7 that are labeled fire clay.   Before I call and start asking them questions, I would like to know what I should be looking for in a fire clay.   The supplier is called Portland Pottery.   Their fire clays are named Goldart, Hawthorne 40 mesh,  Hawthorne 50 mesh, Lincoln fire clay, Pyrax, Pyrotrol, XX Sagger.   Also, in their pictures, it looks like they are selling clay in big sacks, which makes it look like the clays are dry.   That seems good to me, since I will need to mix it up with sand and water and starting with dry clay seems like it would be easier.   Is anyone familiar with these clays and/or have any experience building a dome starting with dry clay?   Thanks so much.  -Varda

willwork4SD's picture
willwork4SD

Hi Varda,

I'll start off by saying I have no experience in dry clay. Sorry. I have read some threads on the Forno Bravo forums about it, though, you may check there for info also. When I needed a clay source for my oven, I contacted a brick company nearby (New England) that makes brick for construction purposes. I showed up there with a bunch of 5 gal. buckets and a shovel and asked if I could purchase a small quantity of clay. They just pointed to a huge pile of almost pure gray clay and said help yourself. It was really nice of them. Not sure if you have such a manufacturer in your area, but it may be worth a try, unless you're commited to the dry clay.

Hope you get what you need to be up and running again.

SD

 

varda's picture
varda

Boston Metrowest.  Right now I have a bias against just digging stuff up given what happened last year, and I was hoping to work with a clean product even if it costs money.   But I have to ask - how many of those 5 gallon buckets did you use for what size oven and what did you do for sand?    And what/where was the company?  Thanks so much!  -Varda

sphealey's picture
sphealey

Here's a useful discussion of fireclay for home ovens, written in Rado's inimitable style:

http://www.traditionaloven.com/articles/101/what-is-fire-clay-and-where-to-get-it

Assuming that you goal is a basic low-tech mud oven rather than a built-for-the-ages engineered oven system, I would personally go with either the cheapest (since the odds are any commercially processed and graded fireclay will perform better than any randomly dug backyard clay, yet per Mr. Dozier backyard clays generally work fine) or the Hawthorne product that is in-stock (because some of my neighbors probably work at that company).  

sPh

 

varda's picture
varda

Yes, I'm not building one for the ages, but I would like it to last longer than last year's model.   And I am looking at the website of Portland Pottery in Braintree.  My neighbor who is a sculptor recommended them.    After posting on this site, I saw a recommendation to the Yahoo group Brick Ovens.    So I joined that, and immediately got a referral to the Hawthorne 40 product.  I guess that's the standard for fire clay.  Thanks for the link to the article.   I'll take a look. 

willwork4SD's picture
willwork4SD

I made 2 trips with the trunk of my car hanging on the ground, the stuff is heavy. The inside diameter of the oven is 25inches, 16inches high. The thermal wall is 4-5inches thick. The sand was just regular mason's sand I picked up at Lowe's. The name of the brick company is Stiles and Hart, google them for their web site. I'm on the South Shore, maybe 15-20 miles from the place.

I will say that it is hard work to mix the sand into the wet clay, especially at the 4:1 ratio I used due to the pure nature of the clay. I wanted to be sure that it didn't shrink too much when it dried. So far, so good. There were no cracks at all in the thermal layer. I left the sand form in for 1 week because the weather had been wet. It had a chance to dry slowly and set up before the sand came out, and I think that's the key.

Another thing that I did was mix up the sand and clay in batches ahead of time and stored it in a big plastic tub with a lid. I could work at mixing the stuff at my convenience and all the material was ready to go when I got the chance to build the dome. The tub kept it from drying out.

Here's a pic

Just the last smooth coat to go, but there's no rush.

varda's picture
varda

Thanks for the info.   Your oven looks great.   Have fun baking in it.  -Varda