Turning spalted wood can be dangerous, and potentially carries more risk to the wood turner than clean wood does.
Many people correctly question the safety of the fungal spores that can be released as you turn the work piece however there are other risks that are just as important to be mindful of, and these are addressed below.
As an active wood turner, I come across quite a bit of spalted wood mainly because of the location where we live. We reside in a tropical zone where wood breaks down rapidly when in contact with the soil, and this is just the natural process of recycling the nutrients of the wood back into the soil for the next generation of trees.
After 25+ years of woodwork and turning, we feel we have a bit of experience in this field so passing on the information to help you is the right thing to do for us.
What are the dangers with turning spalted wood?
There are a few dangers or risks to be aware of when starting to play with spalted wood. Once you are aware of them it is a simple task to carefully monitor each piece of wood that is spalted to gauge how far you can take that piece safely.
This can only come from experience that you gain as you turn more projects, but the list below is a good starting point for us to consider.
What primary risks are present when turning spalted woods?
- Structural integrity of the wood.
- Holding the work piece on the lathe safely.
To understand why the listed items are risks to be aware of, we have expanded each into its own section below where we discuss the potential dangers, and offer possible remedies to get you past that hurdle.
We also have a sister article titled “is spalted wood safe for food contact?” to help fill in any details this post misses.
Is dust from spalted wood unsafe?
Any dust from working with wood is considered unsafe and dust from spalted wood is no different. It is impossible to know if the dust is dangerous because of the inherent chemicals in any particular wood, or if the spalting is the real danger while the wood dust is benign.
We work on the presumption that all wood dusts are harmful so we take precautions to limit our exposure to it when working with it. By approaching our work with this attitude it removes the question for the most part so we can just get on with the job at hand with a clear mind.
Wood dust can be harmful to us if we allow it to get into our lungs, and some woods have the habit of aggravating the lungs and causing long term damage. It is the fantastic natural patterns of spalting that keep us coming back to using it though.
Fungal spores are also considered a danger and as the lungs have the right conditions to activate the spores, it can be a risk worth knowing about. Many old timer wood workers suffer from debilitating lung problems, so let’s try not to add ourselves to their already large enough numbers.
How can dust from spalted wood be managed?
This is a simple case of wearing a good quality face mask when you are working with any wood, including spalted. It is also a good idea to clean up the work shop once the project has been completed to remove any residual risks from the spores becoming airborne again.
Dust extraction is a good idea to have set up and this can go a long way to removing the risks that come with wood work. If we can keep the air in the work shop clean, we can work with wood long into our old age years and still enjoy it.
Is spalted wood made weaker by the spalting?
Yes, wood is made weaker by the actions of the fungus that causes the spalting. It is a natural process that needs to be understood to be able to gauge the remaining strength of the wood before you start to work with it.
The process of spalting can be described as the slow motion deconstruction of the wood by fungus. Looking through that lens, it is logical to assume that the wood is weaker where spalting is present, and the heavier the spalting effect is present the less strength that wood will have.
Because of the weakness that comes with heavy spalting, some furniture items should be reconsidered if spalted wood was planned. “What is spalting and what can spalted wood be used for?” covers the reasons.
Can spalted wood be made stronger?
No, once the structural integrity of the wood is compromised the best we can do is to stop the decay and stabilize the wood so it can be used in non-structural projects.
There are techniques that some wood workers have employed to stabilize the wood when the spalting is advanced and the wood has become punky, and one of these is based on an epoxy resin that is quite runny.
This can soak into the wood and set hard, and this then allows the wood to be turned in a safe manner, however be aware of the resin powder that is created as you turn this product. It is likely to be nasty, so face and dust protection should be used. The product is called cactus juice.
Can spalted wood be turned safely?
Yes, it can be safe to turn spalted woods, however, there are risks with the fiber strength not being sound enough when the spalting is advanced.
The structural integrity of the wood can be compromised by the fungus. This is a certainty if the wood is left on the ground where the fungus has entered the wood.
As we mentioned at the beginning, there are other risks to be aware of other than the spores in the wood. To safely turn any piece of wood, it needs to be help onto the lathe in a sound way.
This can include chucks, faceplates, and drive dogs, but they all require the wood to be firm and stable where the wood meets the machine. Spalted wood is wood that has been subject to decay, and the patterns that we see are the evidence of how advanced the decay is in the piece of wood.
It doesn’t matter what method you want to use to hole the wood on the lathe, if the wood is weak, then you are going to have problems.
Every experienced wood turner will tell you that having a lump of wood come off the lathe as you are turning is no fun, and the chances of wood that is spalted coming off as you are turning it are increased more and more as the spalting becomes more advanced.
The wood turner needs to be mindful of the potential for the spalted wood to come of the lathe if turning at high speeds, because the lignin that holds the wood together can be decomposed within the wood where you cannot see.
This can create fracture points where the wood can separate into several pieces while you turn it and this is best to be avoided where possible. Light cuts with sharp tools are recommended.
How can spalted wood be held on a lathe safely?
This is directly the responsibility of the wood turner, and is a judgement call made at the lathe. If you use chucks to turn your projects, you need to be able to grab the wood without easily crushing it.
Heavily spalted woods are often very soft to the point of being punky, and these cannot be safely held with a chuck.
Face plates are another option, but they require sound material to take the screws that fix the faceplate to the wood. If the spalting is not too advanced, this method of mounting the wood on the lathe can be effective, but make certain that the wood is sound where the screws are located.
Drive spurs or dogs can be used if you want to work between centers but if the fibers of the wood are decayed, the drive dog on the headstock end is likely to spin without turning the wood. This can happen with all woods anyway but it is more likely with soft spalted woods.
The final decision for the wood turner is whether to continue with that particular project with that wood, or to give the project a pass as the risk to reward doesn’t add up. The message here is to play safe and smart as there is always more wood available somewhere that is more suitable and sound.
The patterns and detail that spalted wood can hold can be captivating, and it is understandable why so many wood turners look for this type of wood. You can even begin to explore making spalted wood yourself, and “Can any wood be spalted?” looks at this topic.
Because wood turning is often done alone or in very small groups, it is up to the wood worker to check the safety procedures are in place when dealing with any wood, and as you should now be aware, spalted woods elevate many of those risks.
The final message we will leave you with is that wood turning with spalted woods is very rewarding, and it can be done safely, within reason. Play safe.