Can resistance to rot be improved with home heating?

There is a process by which wood is heated several times in the absence of oxygen to improve its mechanical properties and to make it more resistant to rot.
See also these questions 1, 2.

Would it be possible to get some of the benefits by heating wood in a home oven to around 200 degrees centigrade? Specifically I would like to make pine planks less resistant to rot so I can use them outside.

The original process requires the absence of oxygen and demands high pressure, none of which are possible in a kitchen oven.

Woodworking Asked by Ivana on December 24, 2020

1 Answers

One Answer

To answer this question:

Can I heat-treat wood in a similar manner to the quoted paper and get the results I want (resistance to rot), with none of the downsides mentioned in the same paper?

The short answer is, no.

For your purpose there isn't much benefit, even if it would work (which it will not), because many of the benefits of using wood for a chair are also changed with this process. Most of the strength was reduced, and especially the elasticity. There was a gain in compression strength that you didn't need in the first place. (A chair will only see so much compression testing from a human sitting in it. Elasticity and resistance to racking are way more important for furniture like this.)

As for the rot-resistance, I remain unconvinced. It reduced some fungal attacks, probably by removing or converting the only part of the wood that fungus likes to eat. Basically, it did the job the fungus wanted to do, just quicker?

But what about all the other things in the world that want to eat wood? Fungus is only one aspect of what we call "rot". A good part of wood breakdown is simply exposure to elements that cause the wood to move away from glue and fasteners, and UV light breaking down the connections in the wood itself. Insects like ants and wasps would still be interested in making paper from your furniture, if they get the chance.

The authors make this very clear:

Although heat treatment is an effective modification method to improve the dimensional stability and resistance against fungal attack there are undesired side effects, mainly due to the high temperatures involved (150–280◦C). Reductions of mechanical properties of wood were noticed after heat treatment, e.g. the resistance to shock, modulus of elasticity (MOE), bending strength (MOR), compressive resistance, shear strength, and abrasion resistance.

However, more to the point, this process does not allow the carbon in the wood to easily combine with oxygen (which carbon really wants to do). So in your oxygen-rich oven all you would be making is really, really slow charcoal. You would not get the purported advantages of whatever mechanical or chemical process is going on at low-heat low-oxygen environments.

So, to recap:

  1. You can't really reproduce what they are doing in this paper.
  2. Even if you could, you don't get any real advantage in doing so.

Correct answer by jdv on December 24, 2020

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