How-To: Dry Timber at Home

Congratulations, you’ve cut down a mighty tree or got hold of some freshly felled wood and you’re going to be turning for years absolutely cost free on wood...well hold that dream and see how to get the best chance of seeing it come true - in our eyes anyway.

Firstly, what follows is no guarantee to success, just a set of thoughts cobbled from experience which I wanted to share with those looking to dry timber at home (and assuming you don't own a kiln!)

The principle objective when drying your own timber is to end up with relatively dry wood but without drying splits - or not too many or too deep at least. Note the term "relatively dry": it is unlikely, at least in temperate latitudes, that you will dry timber down to in-house moisture levels. For stability in a centrally-heated environment, you need to get the moisture to around 8%; for most everyday uses a finished MC (Moisture Content) of 12% would be considered reasonable: your home-dried timber won't normally get below around 15%-18% before you move it to a drier environment.

The key to avoiding splits etc. is speed - or more importantly - the lack of it. Maybe I should say "slowness" but it sounds an ugly word. This is achieved in two ways: slowing the rate of moisture loss and making the loss more even across the piece of timber.

Slowing the rate means keeping you timber in a sheltered, COOL, dryish (but not de-humidified) location. Beware of air conditioning and central heating systems - keep your timber somewhere else whilst it dries. Keep it out of drafts/draughts as air flow increases the rate of moisture loss. On the other hand you need "airiness", not stagnant air, around your timber unless you are after spalted (fungally-infested) timber. If the timber is outside, it needs to be sheltered from both sun and rain as well as away from the direct effects of wind. If you have hot summers, try to cover the woodpile with something that will prevent the timber baking. If you have a cellar/basement with a stable summer/winter temperature, then this is the place I would choose for my timber store (assuming you're not into drying tree trunks.)

Evening out the rate of drying is the final point. Wood loses moisture faster from the ends of the piece (the face cut across the grain) since this is the open end of the timber's cells. The moisture loss radially (i.e. out through the cambium layer and the bark) is very much slower. You need to equalise the rate of loss. This is normally achieved by coating the end of the timber with something to slow down the rate of loss. "Traditionally" this has been the application of paraffin wax (candle-wax in its crudest form) which needs to be melted, then brushed across the grain and onto the bark face to create a sealed environment. Other things that have been tried with greater and lesser success is old oil-based paint; grease, clingfilm etc. The one method which generally works pretty well is to use a proprietary timber sealant such as Chestnut Products "End Seal": this is applied cold, dries quickly, doesn't clog up the application tools, leaves a clear film through which the timber can be seen and leaves no problematic residue on the timber when you come to work it. If you haven't seen this stuff or can't get it at a local store (it is not particularly common) then take a look at The ToolPost website (http://www.toolpost.co.uk) and you'll find it listed on the "Finishes" page from where you can buy it without moving out of your armchair. It is very economical in use so a little goes a long way. You'll also find paraffin wax listed in the same area with the Liberon finishes.

A note on cutting the timber is pertinent here: don't try to dry timber "in the round". You must split it down lengthwise through the pith to have any reasonable chance of success (yes, there are always exceptions, but these are notes, not a treatise!). Ideally cut your timber such that you "box out" a square section of about 2" square containing the pith. I know it hurts to appear to lose so much timber, but its that or lose the whole lot - and you will still get two planks of 2" thickness, roughly the width of the tree's radius (less one inch) so it's not too bad!

A final point: whatever method you use, don't expect 100% success. If you get 70% to 80% or better, then you're in good company. Wood is a natural material and whilst God doesn't give warranties, he's good at challenges. One thing is for sure: if you follow these guidelines, you'll have a much better success rate than if you don't.