Green oak and moisture content

How long does a piece of green oak take to season? It’s a question that I am frequently asked and the stock answer that most of us give is that it seasons an inch a year. So if you have board 25mm thick it will be pretty much fully seasoned in 12 months whereas a thicker 100mm piece would take around 4 years.

While I was making the bench for the One Oak project I took the chance to measure the moisture content of the timber I was using. When it was cut in January a year ago the timber had a moisture content of around 43%. It was then sawn in late February and stacked outside to start to season. I picked up the boards I used in my bench in November so they had had 9 months of seasoning. The 30mm thick boards were down to 18% moisture contect – that’s pretty much fully seasoned for air dried timber and I suppose where I would expect them to be after a dry summer. The thicker 80mm board was around 29% m/c in its centre, quite a bit drier than I expected but perfect for the type of furniture I make. It is still easy to work with being nice and soft, and much of the shrinkage that occurs as it dries has already happened, meaning that the furniture won’t move around too much or split.

It still going to take another few years for those thicker bits to fully season.

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4 Responses to Green oak and moisture content

  1. Vlado Sajan says:

    Hi, I am from Slovakia and I like much your beautiful green oak furniture and I am thinking how to make something similar at my workshop.
    Anyway here in Slovakia is almost no information about how to make furniture from green oak.
    So I would like to ask you a lot of questions about green oak but there is probably no time for you to answer…
    Would you be so kind to tell me following basic info?
    As I red at your articles if I have board 5 cm thick I can use it for furniture after 24 months – are there any rules to choose the right boards for seasoning?
    Next question is if you use any glue for joining of parts or do you use only pegs / tenons? Is it the same way of making for indoor and outdoor furniture?

    Thank you in advance for your answer.

    Have a nice day

    Vlado

    • Rodas Design says:

      Hi Vlado,

      I don’t season much of my timber but when I do I choose the best boards – those without too many large knots as these will make the board distort as they dry.

      I never use glue with green wood. As the timber seasons you will find that it will probably break the glue within the joint as the timber shrinks more in some directions than in others. Nearly all of my joints are pegged mortice and tenon joints.

      The best way is to experiment and see how things work for you.

      All the best,

      Rodas

  2. andy thomas says:

    Hi
    I have read your blog and its very informative. I wonder if you can help me?
    I am about to make 2 tables using sewing machine treadles. This will involve using 2 x 35cm wide green oak planks 25mm thick. I was going to put a piece of wood or metal underneath the planks and screw that into the oak to keep them together (I was going to glue them as well but have read that this is pointless) Then i would mount this onto the treadle (so it would mean a screw in each plank left and right) Would this work? or would problems occur as the green oak dries)
    Many thanks in advance
    Andy

    • Rodas Design says:

      Hi Andy, the oak will shrink across the grain as it dries so you will get a gap developing between the two boards. Usually shrink about 5% so gap will be around 15mm. You can just close up the gap and re-screw the piece of wood underneath. Also the boards are likely to cup (curve either up or down) across the grain. The oak curves towards the outside of the tree as it dries so usually best to place your boards with the outside down so that water doesn’t pool.
      It’s usually best to use air-dried oak in this situation as it’s much more stable!
      Good luck, Rodas.

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