How Do We Dry Out Our Timber and Why?

Do you want to learn a little more about the drying processes of our timber? Then you’ve arrived at the right place! We hope this blog goes some way to help explain why and how we dry out our timber at Whitwell Sawmill.

Firstly it’s worth noting that our wood drying process varies depending on the type of timber in question. The simplest form of drying comes for wood types that contain very low levels of tannins. This is timber such as Beech, Ash and Maple. We can plank this timber on the sawmill and then (assuming there is space) we can pretty much put these slabs into the kiln straight away. During the first week of the kiln cycle the timber is steamed at 70 degrees. This opens up the pores of the wood and allows it to evenly dry out. Because this timber has natural moisture within it the kiln uses this to produce the steam, so there is no need for us to manually add any water – something which you will later find is different when dealing with Oak or Chestnut! After this first steam cycle the kiln in then gradually reduced to 35 degrees, allowing the moisture to escape and wood to dry out. The temperature of the kiln kills off any bugs, eggs or insects at about 55 degrees so this is of no future concern. The planks are left in the kiln for a further 5-6 weeks before we empty it, at which point it is ready to sell and put to good use!

For woods with tannins the drying process is slightly different and much more lengthy. Timbers such as Oak, Cherry, Chestnut and Walnut fall into this category. Firstly they need to be sliced on the sawmill and then we seal the ends of the planks. The planks are then stacked outside with sticks in between them and we put a roof on the stack to keep the worst of the rain off. It is important that this timber dries slowly and air is able to circulate between the planks. These planks are then left to air dry for approximately 9 months before we can even think about moving on to the kiln stage. It is also worth noting that we aren’t able to plank timber in too hot direct sunlight because there is a risk that the surface will dry out too quickly and the middle will still be wet which will create surface checks (small cracks).

Once 9 months has passed these types of timbers are now ready to go into the kiln. The process is actually the same from this point, other than we now add some water to the kiln this time round to provide some moisture for steaming. Due to the air drying process the kiln cannot get water from these types of timbers. If we had skipped the air drying process and put these planks straight in the kiln then it is said they would go black! Not something we have ever tested out – in theory the wood would still be usable but not a desired colour preference.

Hopefully this goes some way in providing an insight into the timber you are buying and how it has been prepared to get it to the point of being usable.