Spalted Wood. How wood spalts.

Spalted wood.

Spalted wood is where fungus or more usually several different fungi have been introduced to the wood. This is most commonly after the tree has been felled but sometimes it is a fungus which has killed the tree so the timber has already been spalted. Spalted wood can be created deliberately or can occur by accident as I have found out several times over the years!

Spalted wood can be created as easily as:- Leaving the freshly sawn wood out in the weather, popping it into a plastic bag or burying the wood in wood shavings.

However, knowing when the wood will be spalted enough to work but not too spalted is as tricky as :- Knowing when to take a cake out of the oven without a temperature gauge or knowing when to put fuel in a car without a fuel gauge.

But it is so very exciting to see if you have got it right. And when it is right it feels like hitting the jackpot. Since I have become old and boring it is about as exciting as I wish life to be.

The ease with which I can glibly say the above is because over the years I have unintentionally spalted much wood. All the wood I use is local and fell naturally or had to be felled or coppiced for some other reason and I’ve been lucky enough to be able to buy the wood. So if for example I’ve had a short piece of wood which I knew would crack if left out I’ve wrapped it in plastic intending to turn it within a couple of weeks only to forget it or get distracted and not get round to it for months and then wonder of wonders, it was beautifully spalted. Other wood has waited months outside in the rain until I plank the tree trunk. So, no fuss and worry seems to work well. There has been wood tightly wrapped in plastic excluding all air, loosely wrapped allowing air, left in a damp environment without cover. They all work. The biggest hit and miss is deciding when to use the timber thereby stopping the spalting process.

Spalting Wood.

The best and easiest way to create spalted wood is to use green wood as this is the most natural way the fungi would be going  into wood to start the decay process. Over time and with experience it might be possible to try to regulate it by noting how long it had been left in different environments. However, in my experience there is a massive difference between different wood species and even different trees of the same species. All it needs is for one tree to be felled in the winter and another when maximum sap is rising and the difference in the wood is enormous. So there will always be an element of surprise.

I have never tried spalting a dried/seasoned piece of wood. Air dried wood would be slightly easier than kiln dried as it has a slightly higher moisure content and the cells themselves won’t have collapsed so much. To spalt dried wood I would make sure it had enough fungal spore by introducing them rather than my happy go lucky way of leaving wood around or just popping it in a bag. Pick up a few handfuls of rotted leaves or a rotten piece of wood if you can to put in the plastic bag and the wetter they are the better as you would have to re-introduce moisture too. Even more important with kiln dried wood. But it is always more difficult to reintroduce moisture to wood. Firstly it is the area around the cells which lose moisture. But after you get down to about 30% moisture it will be the moisture within the cells themselves that is coming out and the cells collapse. So creating a suitable environment for fungi to do their work on well seasoned wood is much harder.

I prefer to work the spalted wood as soon as possible after planking it or taking it out from the plastic. I find that the structure of the wood through its alteration by the fungi means that it is more likely to crack than either green wood or seasoned wood. The moisture within the wood is water not sap as it is the sugars in the wood which the fungi have been eating. So it will dry quickly on exposure to a drier atmosphere.

Spalted wood and what causes it and when and how is a little understood and much misunderstood subject. But it is just nature trying to do her thing. And the results are so beautiful, aren’t they?