Kiln dried timber and heat treated timber processes are different methods. Although they both involve heat, one is to sterilise wood, whilst the other is to remove the moisture from the wood. Here, TIPCI Group explains the difference between kiln dried and heat treated timber processes.

Kiln Drying

Kiln drying is a process where the kiln is used to dry out the wood and therefore reduce the moisture content. Kiln drying is typically done at much lower temperatures than heat treatment and the process can take a number of days. It is a meticulous process and the purpose is to reduce the moisture content of the wood to lower than 19% in a way that doesn’t bend, warp or misshape the wood. 

The Benefits of Kiln Drying

When the wood is dried, the wood becomes more dense and lighter as there is reduced moisture in the wood fibres. This can create a benefit for wood packaging because it reduces the weight of the material, making it more cost effective to transport. Kiln drying increases the wood’s resistance to pests and insects, because the denser wood makes it more difficult or insects to get into the grain. However, the treatment is not as effective as heat treated wood for pest repellent. Kiln dried timber also builds the wood’s resistance to mould and, if the wood is kept in a dry environment, will maintain the mould resistance. However, the mould resistance is again not as effective as heat drying. The primary benefits of kiln drying are about making the wood lighter and being a specific structure or shape and is often dried to a client’s specific requirements.

Heat Treating

The process of heat treating wood happens in just a few hours and the result is sterilised, bug-free and bug resistant timber. The heat treatment occurs at extremely high temperatures, which eliminates any pests. Heat treatment is the more common process and it is a required process under the ISPM15 regulation, when importing and exporting wood packaging, including pallets. The ISPM15 regulation exists to ensure that all wood packaging is sanitised to control pest infection around the world.

Read more about ISMP15 here

The Process of Heat Treatment

The wood is placed into a kiln under temperatures that reach 56 degrees Celsius, which are sustained for a minimum of thirty minutes. 

The Benefits of Heat Treatment

Heat treatment is a sterilisation process and therefore the main goal of heat treatment is to kill pests and other living organisms. As mentioned above, this is required under ISPM15 for wood packaging used for importing and exporting. The wood however will not change, which is usually the goal of kiln drying. However, the heat treatment process does not deliver the same benefits of the kiln drying process, which can dry wood to specific requirements of shape and weight.

Should I Use Heat Treated Pallets or Kiln Dried Pallets?

If you are using pallets for importing and exporting then you are required to use heat treated pallets under the regulations of ISPM15. This ensures you are being responsible by preventing potential pest (and other organisms) infestations across the globe. However, if you require to use your pallets solely in the UK, and in fairly dry environments such as pallet racking storage, you may wish to opt for kiln dried pallets to reduce the weight for transportation and storage.  Kiln dried pallets are also recommended if you have very specific dimensions or shape requirements for your pallet.

For more expert advice, please contact us.


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