Wood Fired Ceramic Kiln – Firewood Basics

Firewood is somewhat complicated.  The following things should be kept in mind.

1.  Size matters!  The smaller the pieces, the faster heat can be released given a larger surface area of wood that is present in the firebox.  The primary air inlet is 3″ x 4.5″ so wood that fits through that port would be ideal.  This is easier said than done with some wood species such as elm which is quite difficult to split.  However, oak and cherry is significantly easier.  The length of the firebox is 36″.  In order to maximumize the volume of the firebox the wood should be ~32″ and occupy the entire length or ~16″ and be charged from both ends.

2.  Wood must be seasoned and dry.  Ideally wood should have been cut and split one year prior to use and been stored under dry conditions (out of the rain).

Wood species is also something to consider.  Softwoods give off heat much faster.  Hardwoods give off heat slower but have been known to yield better results in the pottery, but not all hardwoods are the same.  Below are some heat contents of common domestic species in millions of BTUs per cord (128 cu.ft.).

White Ash – 22.3

Black Ash – 19.1

Cherry – 20

Elm – 19.5

Hickory – 27.7

Maple – 21.6

Red Oak – 24

White Oak – 25.7

Red Maple – 18.7

Black Walnut – 21.5


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