Appendix 2. Brick Primer
Deciding what type of brick you will use is one of the first
choices you will have to make when starting to build a
Pompeii Oven. You will use brick in the cooking floor, the
oven dome and perhaps for your decorative vent arch, oven
landing and other decorative trim.
This page explains the different types of bricks and what the
trade-offs are between them. It should help you decide what
types of brick you are going to use, and it can help you find
the right brick at your local masonry supply store. It might
be useful to take this page with you when you go shopping.
Here are some basic brick types:
Medium duty firebrick.
We recommend medium duty firebrick for both the cooking
floor and dome of the Pompeii oven, and it is the type of
firebrick we provide as part of the Pompeii Oven Kit.
Medium duty firebricks are comprised of roughly 38%
alumina, and are highly compressed and kiln fired. They
heat up quickly, easily withstand the 1000ºF heat your oven
will reach, and are designed for the rapid heat-up and cool
down (thermal cycling) that your oven will experience. This
type of firebrick will also reach the heat required for baking
Pizza Napoletana pizza quickly than clay brick, as they are
more efficient at conducting heat.
Further, because firebrick is designed to withstand thermal
cycling, your oven will last longer, though for most home
ovens this is not an important issue, and your oven will
probably outlast you—whichever brick you choose.
When choosing your firebrick, look for a brick with straight
edges for your cooking floor. It is important that the bricks in
the floor fit snuggly against each other, and a curved edge
will result in a gap between the bricks and in your cooking
floor.
A typical medium firebrick weighs a little more than 8
pounds and is yellow. The price of a good quality firebrick
should be around $1.20.
Low duty firebrick.
This is the basic fireplace firebrick stocked by many
masonry supply stores. They have a lower alumina content
than a medium duty firebrick (around 30%), they have more
non-refractory impurities, and they are less dense. That
said, low duty firebricks are a good choice for building a
Pompeii Oven, and other than considering the Pompeii
Oven Kit from Forno Bravo, it is not worth the effort of trying
to find a higher quality firebrick in your region. With gas
fireplace insert replacing firebrick fireplaces and the
modernization of heavy industry, it is becoming increasingly
difficult to find high quality firebricks.
Red clay brick.
This is the traditional red clay brick that you find at Home
Depot and at masonry supply stores. Clay bricks are made
from clay, and fired in a kiln. They are typically made from
local clay, as shipping is too expensive, and fired to
between 2000F - 3000F (high enough to fuse the minerals).
You can use clay brick in the oven dome, but we would not
recommend using them in the oven floor. There are trade-
offs to consider.
There are two shortcoming to using a clay brick in your
oven dome. First, thermal cycling will cause clay brick to
spall, where little pieces of the brick flake off, and could
cause individual clay bricks to crack. It has happened to us.
Second, clay brick is not as good a conductor as fire brick
and as a result will take longer to heat up.
Still, you can find clay bricks for about $.25 at Home Depot,
which make them the most cost-effective option.
Our view is that unless cost is a prohibiting factor, we would
recommend firebrick. For example, a 42" oven some has
roughly 180 bricks in the dome, so the difference in brick
cost should be around $100. In the context of the overall
cost of the oven, and large amount of human capital you will
be investing in your oven, we think the extra cost of worth it.
If your choice is to build your oven with clay brick or not at
all, we would strongly recommend building your oven with
clay brick.
Pompeii Oven Instructions
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