How to kiln dry firewood

logs in cages

All the logs that we sell here at Firewood Centre are kiln dried. This means that they have had their moisture content reduced in a controlled way to between 10 and 15% of the logs’ volume, which is considered extremely low by industry standards. This makes them ideal for burning in wood burning stoves and open fireplaces where they catch alight easily and burn long and hot without the smoke and soot generated by wood with a higher moisture content.

But what does the kiln drying process actually entail, and why are kiln dried logs more desirable than logs that have been seasoned outdoors?

Industrial kilns used for drying wood are large and specifically designed for the purpose. They are very different to pottery kilns which are smaller and hotter and not at all suitable for drying wood. We would go as far as to say that it would dangerous to try and dry wood in a pottery kiln as the high temperatures and lack of ventilation could cause the wood to char or even catch fire.

The industrial kiln will have a large chamber in which the wood is stacked in bundles. Heat is introduced to the chamber via piping that ensures air is circulated evenly within the space and the wood is dried in a controlled and consistent way. The kiln is not as hot as you might think and operates at about 80 degrees centigrade for drying most types of firewood. At this temperature it would take about four or five days to reduce the moisture content down to about 15%. At this point it is removed from the kiln and stacked ready for packaging.

The process of creating a high-quality firewood product doesn’t stop there though. Wood is a hygroscopic material which means that it can absorb moisture from its environment. Wood that has been seasoned outdoors for a long period of time can actually reabsorb moisture during damp weather. Logs that has been seasoned for over a year could absorb enough water to make them useless as firewood until they dried out again. Using seasoned wood can therefore be a bit of a lottery. You can reduce your chances of putting a damp batch in your wood burner by using a moisture meter to check if the logs are suitable. If they aren’t you can leave them indoors for a few days to dry out, or better still return them to the supplier.

With kiln dried logs you get a very consistent product as once the kiln drying process is complete the logs are not exposed to the elements or any dampness that could lead to increased moisture levels. The packaging, transport and delivery process is also designed to ensure that the logs are never exposed to any environment that will impact their quality. The slight premium that you pay for kiln dried logs is well worth it given the time and resources that have gone into the process of creating a high-quality product that will give you hours of heat in your wood burner, fireplace or patio heater.