I have a PhD in Forest Science and professionally research the interaction of fungi on wood for the value-added wood process of spalting.

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Spalt Your Own Lumber: What's In A Name?

Names and marketing have a strong hold over us. With all the 'specialty' woods out there, how do you know what is spalting, what is tree color, and what is made-up to increase sales?

Spalt Your Own Lumber: Yellow Zone Lines on Aspen

A continuation on our look at colored zones - investigate the yellow zone lines of aspen and help speculate on what fungus could be responsible.

Spalt Your Own Lumber: Outdoor Spalting

We all know that outdoor spalting works, but can be unreliable. Learn a few tricks to help direct the process.

Spalt Your Own Lumber: Fungus of the Month - Violet Toothed Polypore on Birch

Some fungi work best on a very specific host. Check out the incredible zone lines created by the Violet Toothed Polypore on birch!

Spalt Your Own Lumber: Fungus of the Month - Fomes fomentarius

Fomes fomentarius loves birch like rabbits love carrots! Learn how to get some serious zone lines with this fungus.

Spalt Your Own Lumber: Lets Talk About Health

Once a year or so, its nice to remember why we should be level-headed about spalted wood and its so-called health impacts.

Spalt Your Own Lumber: Fungus of the Month - Arthrographis cuboidea

Arthrographis cuboidea is the best pink stain to use when spalting. Learn how to find it, culture it, and get it growing in your spalting tubs at home.

Spalt Your Own Lumber: Its not all about the fungus!

Wood species plays a big role in the amount and type of spalting you get on a piece. Learn how to hedge your spalting bets with the right wood.

Spalt Your Own Lumber: Nutrient Supplements for Spalted Wood (e.g. beer)

The internet is filled with 'recipes' for spalting. Join me in analyzing and debunking each one of them.

Spalt Your Own Lumber: Just Say No To Brown Rot!

Brown rot is white rot's evil twin. Learn what to look for to avoid this destructive type of fungus.

Spalt Your Own Lumber: Dissecting the Colored Molds

Molds are responsible for many of the bright colors seen on spalted wood. Learn to tell the difference between the useful, the irritating, and the potentially hazardous.

Spalt Your Own Lumber: Drying Spalted Wood

Drying spalted wood can be a lot easier than drying clear wood. Learn some of the basic tricks here.

Spalt Your Own Lumber: Optimizing fungal growth

Fungi grow in specific directions in wood. By optimizing your placement of mushrooms you can speed the spalting process.

Spalt Your Own Lumber: Zone lines get even more mysterious

Zone lines don't just come in black, as many people think. See some of the variations and help me brainstorm on the possible causes.

Spalt Your Own Lumber: Fungus of the Month - Oyster Mushroom

The oyster mushroom isn't just a tasty treat - it can also spalt your lumber!

Spalt Your Own Lumber: Fungus of the month - Dead Man's Finger and Turkey Tail (part II)

See the photos that accompany part I on locating Dead Man's Finger and Turkey Tail.

Video: Spalt Your Own Lumber: Fungus of the month - Dead Man's Finger and Turkey Tail (part I)

Learn how to quickly locate Dead Man's Finger and Turkey Tail, the two most prolific zone line producing fungi.

Spalt Your Own Lumber: Fungus of the month: Green-stain Chlorociboria

Learn about an easy to find green-stain fungus

Spalt Your Own Lumber: The deeper meaning of zone lines

Discover the many types of zone lines, and what they mean when you see them on spalted wood.

Spalt Your Own Lumber: Health problems associated with spalted wood, and debunking myths

Learn about safe handling, storage, machining and use of spalted wood.

Spalt Your Own Lumber: Is it spalting? The case of the mysterious host-response color.

Spalting is often confused with a host response color produced by the tree itself. Learn to tell the difference.

Spalt Your Own Lumber: Introduction

An introduction to spalting... plus see some pink and yellow spalting on hemlock that Robinson cooked up in one of her home spalting tubs.

Recent comments

Re: Spalt Your Own Lumber: What's In A Name?

@netserv666: I am familiar with the red staining that can occur from chainsaw oil, but rest assured that it is completely different from the pink/red stain produced from 'Arthrographis cuboidea', as well as the red stain produced from boxelder/Manitoba maple trees.

Re: Spalt Your Own Lumber: What's In A Name?

mightwombat - I know I know! How could I have missed such a huge opportunity to be punny? I'll do better next time.

Sodabowski - I occasionally stumble upon your lumberjocks page, so I'm moderately up to date on your Chlorociboria work. Glad its working out! We finally cracked it in the lab in terms of culture growth, and are now trying it out on logs. I'm hoping it works this first time around, because quite frankly, after 7 years of fussing with it, I'm ready for it to actually function like the rest of our well-behaved spalting fungi!

Re: Spalt Your Own Lumber: Zone lines get even more mysterious

Thomas -

Sounds like you found a log early in C. aeruginascens' colonization. It is rare to have zone lines with C.a., mostly because the fungus is a very late stage colonizer and usually won't get at wood until it is almost mush. The C.a. on that particular log hit a still-intact zone line (not produced by C.a., but from a previous colonizer), and could not jump the line. Zone lines are fantastic for herding the colored fungi, and you can use that to your advantage if you ever want to induce spalting.

I'd love to see some photos. You can e-mail me through my website, which is linked at the bottom of the above article. You might also be interested in this article:

I had a look at your lumberjocks site. You mentioned that the pigment is unstable at high temps - its not that its unstable, but that it runs! High temps help the pigment disperse, which is another way to get a little bit of green through a big piece of wood if you, say, heat it up in the microwave.

Always great to meet another spalting enthusiast!

Re: Spalt Your Own Lumber: Yellow Zone Lines on Aspen

If you can think of it, we have poured it/pressure treated it/injected it into wood. Unfortunately, there is a difference between the types of sugars you could add to wood and the type there when the wood is green. Blue stain fungi still colonize rehydrated wood, they just don't produce much (if any) blue color.

There is something specific about the ray sugars that just drives blue stains crazy. Half the time we can't even get them to grow blue on petri plates. Luckily its easy enough to get them on green wood, so we've just stopped with the inoculations altogether. Sometimes, Mother Nature just knows best.

Re: Spalt Your Own Lumber: Fungus of the Month - Violet Toothed Polypore on Birch

Thanks Dennis!

Re: Spalt Your Own Lumber: Lets Talk About Health

@ n7bsn - the important point in your post being that this Cryptococcus gattii is NOT a spalting fungus. Its not even a fungus. In fact, its a yeast, although its potential teleomorph - Filobasidiella bacillispora, is a fungus.

So before everyone gets all riled up about a killing yeast (OMG lets all stop eating bread!) remember that the lovely spores of C. gattii are airborne, so they're not going to be inside your wood, waiting to get into your lungs. You're much more likely to get into a fatal car crash on your way to work tomorrow (way, way more likely) than you are to die from inhalation of these yeast.

And since they're not wood colonizers, why worry about them in terms of woodworking at all?

Re: Spalt Your Own Lumber: Lets Talk About Health

Unfortunately, I think to nip the spalted wood fear in the bud would have required this post to have been made about ten years ago - which is roughly when I started my post-secondary education. And the fact that woodworking magazines (Fine Woodworking aside, of course) still seem stick little lines in their articles like "working with spalted wood can be dangerous to your health" is not helping things.

It makes me want to respond with something like "working with wood can be dangerous to your health", or even "breathing can be dangerous to your health". Getting older can be dangerous to your health, too, so maybe we should have that printed on kid's birthday party hats? You know, always best to err on the side of caution.

Hand sanitizer, anyone?

Re: Spalt Your Own Lumber: Fungus of the Month - Arthrographis cuboidea

@Guitarguy -

If it is growing mushrooms, then it is as spalted as it is going to get. Mushrooms are an indication that the wood may even be too far spalted, so I would fell the tree immediately and use the wood.

Good luck!

Re: Spalt Your Own Lumber: Fungus of the Month - Arthrographis cuboidea

Really? And here I thought I was the only one with pictures of fungus on my desktop!

Re: Spalt Your Own Lumber: Introduction

Well, you've got me stumped! Due to the temperatures in the bath, I doubt very much that it is spalting, although I could be wrong. Since it appears to be a surface issue, you could test for spalting by purchasing some 91% isopropyl alcohol (easily available from Wal-Mart) and get a spray bottle for it. Twice a day, spray the surfaces of several test pieces with the alcohol. Continue this process for the normal length of time it takes the pink to develop. If it develops despite this treatment, the pink is definitely not spalting. If the pink does not develop, then at least you have a greater argument for spalting.

If you're really interested in getting to the bottom of this, you could send me a pink piece in the mail, and I'll make a tissue culture from it and identify any fungi that are inhabiting it. That should clear the whole issue right up.

Re: Spalt Your Own Lumber: Introduction

clickerflicker - I need a little more information before I can answer your question. How hot is the water you use for bending? How wet is the wood when you notice the staining and/or when you use the 3% solution (soaking wet, moderately wet, dry)? Does the staining penetrate the wood, or is it only on the surface? Is all of your wood soaked together, or is each species soaked separately?

I doubt very much that the color is spalting, but will need your answers to the above questions to come to a conclusion. Very few fungi are responsible for pink stain on wood (Arthrographis cuboidea and Fusarium reticulatum are the only two). My guess at this point would be that the stain is being caused either by a reaction of the copper oxalate to the wood, to a fungus within the wood, or by some of the pink extractives in the cherry reacting with the oxalic acid (these extractives may have leached into your water bath if the wood is all steamed together).

If you get back to me with some more information, I can give you a better idea. In the mean time, I've included a few links at the bottom which may help you put some pieces together.

Oxalic acid related to crystal production by fungi:


As a mordant:


Re: Spalt Your Own Lumber: Nutrient Supplements for Spalted Wood (e.g. beer)

Doctor Dan - So true! Even with induced spalting, the shape of the turned piece is often dictated by where the spalting lays, not the shape that you, as the turner, are aiming for. I often get comments on my turned pieces from people commenting on the size, shape, or thickness. I have to then explain that I turned following the spalting - in the end, the fungus picked the shape, not me.

Re: Spalt Your Own Lumber: Nutrient Supplements for Spalted Wood (e.g. beer)

lwj2 - while I agree that a mask should be worn when working with spalted wood, this is not because the wood is spalted. You may want to check out some of the previous posts under 'spalt your own lumber'. The fungi that cause spalting are not toxic to healthy individuals.

I think the theory behind the beer is the sugar and malt, not the yeast, as yeast do not cause spalting. Either way, its a waste of beer! I agree I would also rather drink the beer and wait for the spalting than waste the beer. Cheers!

Re: Spalt Your Own Lumber: Nutrient Supplements for Spalted Wood (e.g. beer)

CaptainSkinnyBeard - fungi are very versatile creatures, and grow in almost all environments and under most conditions. I have no doubt that lumber stacked outside in winter spalted. The trick is that spalting is quicker when it is warm, wet, and dark. It most certainly will still happen under less-than-perfect conditions, it just goes a bit more slowly.

Imagine how much spalting you'd have had if the fungi had been given optimal conditions!

Re: Spalt Your Own Lumber: Drying Spalted Wood

kmpres -

1. Yes, some species spalt faster than others. Species in aspen and basswood spalt faster than maples and birch. Oaks don't spalt well, nor do any with a high extractive content, like walnut.

2. Aromatics will spalt, since everything can spalt given the right fungi and the right amount of time. I would recommend against softwoods. You'll want to read my brown rot post for more information as to why. In general, its far easier to spalt low extractive woods, so I tend to stay away from aromatics.

We didn't get much snow this winter in Houghton. It was sad! I actually just relocated to Toronto, to do a post doctoral fellowship. There is even less snow here.

Glad the information helped you!

Re: Spalt Your Own Lumber: Nutrient Supplements for Spalted Wood (e.g. beer)

Thank you!

Re: Spalt Your Own Lumber: Dissecting the Colored Molds

I find you can often get a discount on blue stained lumber at lumber yards, since there are still people who view it as a defect. If you're not interested in spalting your own lumber, its a great way to get spalted lumber for cheap!

Re: Spalt Your Own Lumber: Dissecting the Colored Molds

As far as I know, most people who shop at art shows and fairs for wooden turnings seem to know what spalting is all about. Most woodturners are also in the know. I sell most of my finished spalted pieces to people who routinely go to galleries to select wood turnings, and most of my spalted wood sells to woodturners and wood puzzle makers.

For pricing, I charge based upon the type of spalting. Blue stain is so ridiculously easy to get going that I rarely even increase the price of the bowl. Pieces with excellent zone lines will get perhaps a $10-$15 markup, whereas pieces with a penetrating green stain may be marked nearly $100 more than a plain piece would be. So basically, I charge increasing amounts for increasing difficulty to work with, or increasing colonization time.

Intarsia is wood inlay, similar to marquetry. Wikipedia has an excellent article on intarsia, if you are interested.

Hope I helped!

Re: Spalt Your Own Lumber: Dissecting the Colored Molds

Yes, spalting changes more than just the color of the wood. I was actually going to write about this in a future post, so here is the bare bones version. White rots (cause bleaching / zone lines) digest the wood. Strength properties are grossly affected and as such, white rotted wood should never be used for load bearing applications.

Most stains do not affect the strength of the wood, but most will affect the wood permeability. All this means is that more finish is required on stained wood.

Some types of spalting alter the surface of the wood enough that new types of spalting can easily colonize. Sometimes, pretreatment of wood with one type of fungus is needed before another one can grow.

Re: Spalt Your Own Lumber: Dissecting the Colored Molds

StairpartPros - If you add the spores yourself, you can be sure that at the very least you will get that color. The iffy part is what other types of spalting you might get as well from airborne spores or spores that are already on the wood. You can take out 99% of the guess work though, if you first sterilize your wood before inoculation.

R Williams - Historically spalted wood was used for intarsia. Today it is commonly used as a decorative wood in turnings and for things like cabinet panels (any non-load bearing application). Objects made from spalted wood fetch a nice premium, similar to birds eye maple.

Spalting takes anywhere from a month to years, depending on the fungus you use and the type of wood you inoculate. Aspen spalts more quickly than birch, etc. In general, bleaching and blue stain take the least amount of time, whereas zone lines and other pigments take far more.

You could use dyes and stains, but I think part of the appeal of spalted wood is that it is a natural process. You may be able to pick what colors you want, but you have no control over where they go on the wood, how they interact, etc. It's natures paint, and that, for some, makes it highly intriguing.

Re: Spalt Your Own Lumber: Dissecting the Colored Molds

Spalted wood has been utilized for centuries for artistic work (like intarsia), and today is commonly used by turners. A lot of people have experimented on the conditions necessary to cause the spalt, instead of waiting for nature to do her thing. If you leave a log on the dirt long enough, it will spalt. The problem is, you have no control over what type of spalting you get.

If you do a search here on FWW for 'spalting', you should come up with other blog entries I've done about induced spalting. They offer insight into some of the responsible fungi, and methods for reliable home spalting.

To more directly answer your question - you can easily inoculate your wood with the mold color you want (or the wood decay you want, if you're after zone lines or bleaching). To do so you can either harvest the fungi yourself from the woods, or buy the active cultures online. The mold grows on the wood and you stop the process when you have achieved your desired color. Induced spalting is a heck of a lot faster and more accurate than just letting airborne spores have their way with your lumber!

Re: Spalt Your Own Lumber: Drying Spalted Wood

lbcollier - no such thing as a dumb question! To make spalted wood, just pick fresh mushrooms (or take your fresh sawdust from some cut spalted wood) and place it on your clear lumber. As long as your lumber is moist, and stays moist, the fungus will get into the wood all on its own.

If you're trying to inoculate a large piece, you could also drill some holes into it and shove a spalted sawdust mixture into the holes. That would speed penetration of the fungus.

Re: Building with Choke Cherry

I have worked with choke cherry in the past, and the best advice was already given by blackbogtree - stick the pieces in plastic bags, seal them tightly, and wait. My pieces generally take around 6 months before I'll hazard turning them. Once they're turned, they spend another month or so in bags to finish drying.

Fruit wood can be an absolute nightmare to work with. Best of luck!

Re: Spalt Your Own Lumber: Optimizing fungal growth

Rich -

My guess at this point would be that there is sand in your wood from its time in the lakes. The erosion of the surface along with the opening of the cell walls by the fungi no doubt allows more sand in than a sound piece of wood.

I've done some work with driftwood, and seem to recall a similar phenomenon. It is a unique type of wood. I finally resorted to utilizing Finkat sandpaper, since it was the only type that would hold its abrasive edge for very long.

All the driftwood pieces I finished were finished with MinWax water-based polycrylic. As you noted, that driftwood is a real pain to finish. The water-based finishes go on evenly and provide some added protection to the sometimes punky areas.

Anyway, I don't think your silica is naturally occurring in the wood - I think sand is being forced in there while the wood tumbles around in the lake. Regardless, the effect is the same for your sandpaper. Best of luck!

Re: Spalt Your Own Lumber: Optimizing fungal growth

Rich -

"spalted drift wood has dust plus particles that fall to the floor. Combined with the rapid demise of the sand paper may I assume there is a lot of silica in the lake spalted wood ?"

I'm afraid you'll have to be more specific in what you refer to as 'dust particles'. I would wager, however, that what is falling to the floor is remnants of the wood itself. Drift wood is highly eroded and decayed, and the cell walls are in really rough shape. Any sort of pressure, especially with the heat from sanding, will cause the components to fall apart.

Is your sand paper clogging, or dulling? If it is clogging, then the issue is definitely your eroded wood. If it is dulling (test this by rubbing your finger over a used piece, then a fresh piece), then you probably have a lot of sand in there with the wood. Silica occurs rarely in North American hardwoods, so unless you are finding teak driftwood, you problem is either sand from the lake (probably not) or just a very eroded cell wall (likely).

"Why does it happen to mostly maple?"
The thing is, it doesn't happen mostly in maple. The issue is that for scientific research, you need to stick with one species until you really, really understand it. So a lot of my techniques are based on the requirements for maple specifically.

I've been expanding recently into other woods, and find that basswood and aspen are excellent spalters, but only for very specific types of spalting. Your problems with elm and ash (maybe even cherry) are the extractives. The more extra 'stuff' in a wood cell wall, the less likely a fungus is to colonize.

"what is your suggestion for obtaining a smooth finish? ie no dry patches in a raking light?"
That is a huge question that I've been asked several times recently. I'm working on a comprehensive answer. Finishing spalted wood is complicated, as you have no doubt found out. Hopefully I'll have a step-by-step guide up here or in the magazine itself sometime soon!

Re: Spalt Your Own Lumber: Optimizing fungal growth

Reggie -

Moisture content is a tricky thing for spalting. Get the wood too wet and it won't spalt at all. Get it too dry and you have the same issue. But the MC inbetween those two extremes supports a whole variety of fungi.

Excessive mold when spalting can be due to two things - very fresh green wood (high sugar content) or older wood with a MC so high that decay fungi do not want to grow. Since you mentioned this issue with your spalting pile, I'm going to wager that your MC is too high. But, breathe a bit. Mold fungi DO NOT decay wood - they just eat the available sugars. Let all the mold fungi you want colonize the wood (you'll get the startling colors this way too), it won't affect your wood strength (although it might affect the toughness of the wood).

I'm not going to get too much into MC relations here, as I'm planning a future post on it. However, I would generally recommend keeping MC on the lower end to get the decay fungi going, then boosting it for the colored mold fungi.

Is there a rule of thumb on wood moisture content?
Not that I can easily convey without a moisture reader. If you see mold, its too wet for decay fungi. If you see no fluffy white stuff, its either waaay too wet, or too dry.

and on moisture content for the storage environment?
If you're using vermiculite as the spalting substrate, you don't have to worry about the relative humidity of the storage environment. If not, you'll want to make sure that water is condensing on the top of your spalting tub. That keeps MC cycling.

Good luck!

Re: Spalt Your Own Lumber: Optimizing fungal growth

Peter -

Putting fungi on the surface of the wood generally means that you get a lot of colonization on the surface that takes a long time to penetrate through. For antagonistic zone lines, I'd recommend placing one white rot fungus on one end, an opposing fungus on the other end, and allowing them to grow together. I think you'll find that even if you put spores on the end grain, the mycelium will still quickly cover the surface and give you all those lines you are looking for. However, putting the spores on the end will give you zone lines that run completely through the board.

When I want to be 100% sure of getting internal zone lines, I always utilize the double end grain inoculation method. I have found that just rubbing spores over the surface often produces zone lines that penetrate only a few millimeters into the wood. One quick pass through the planer and they're history!

In terms of pigment fungi - most of them grow radially, so placement of their spores can be on any wood surface. Most of them can't get too deep without a white rot pretreatment though, so if you already zone lined your wood through the end grain, you might as well color it through the end grain as well, as that will be the path of least resistance for the pigment fungi.

Hope this clarifies!

Re: Spalt Your Own Lumber: Zone lines get even more mysterious

Thanks Patrick! Always nice to know people are reading!

Re: Spalt Your Own Lumber: Fungus of the Month - Oyster Mushroom

To be honest, my mushroom knowledge is limited primarily to those that grow on wood. Oyster mushrooms are pretty different from most others I have ever run across, especially in their texture. It'd be pretty hard to mistake one for something else, but I've included some tips below just in case.

The big poisonous ones people worry about are primarily the amanitas; mushrooms known as death cap, angel of death, etc. Those grow from the ground duff, not on logs. They're much more 'mushroom' shaped. Oyster mushrooms are sort of airy and light, and grow ON logs directly, since they are wood decay fungi.

Remember, if you are not 100% sure of a mushroom's identity, DO NOT EAT! Always better to be safe than sorry!

Re: Spalt Your Own Lumber: The deeper meaning of zone lines

Is there any way to generally classify the fungus by discoloration?

Yes, but the key word here is 'generally'. Bleaching is caused mostly by basidiomycete (wood decay) fungi, so if you see punky white areas, you can hold fungi like Turkey Tail as suspect. Pigments are usually from ascomycetes, and depending on the color, you might be able to narrow it down a little more. For instance, there is only one genus that makes the blue-green color: Chlorociboria. It is mostly Ceratocystis and Ophiostoma fungi that make blue stain.

For zone lines, you're out of luck. Many, many fungi have the capacity to produce them either alone or from external antagonism. So unless you see Dead Man's Finger growing somewhere near the wood, you really have no way of knowing what caused the zone lines.

Happy spalting!

Re: Spalt Your Own Lumber: The deeper meaning of zone lines

In general, zone lines indicate white rot decay. So in that sense, yes, wood with zone lines is much weaker than sound wood. Unless you have intentionally spalted your wood with Dead Man's Finger, which is only slightly destructive, its a good bet that some areas of the wood are very punky.

Never fear however! While zone lined wood found outside may be too soft to turn, most anything you spalt at home will still be mostly sound if you've controlled the conditions well.

Re: Spalt Your Own Lumber: Introduction

Sorry mvealey, I only just noticed your comment today! In response to your questions, yes, you can store fungi for later! The fruiting bodies themselves may not keep, but a piece of actively spalting wood will. I suggest sticking it in a ziplock bag and putting it in your fridge (for long term storage) or freezer (for short term, and no, those aren't backwards). The cooler temperatures put the fungus in stasis, but it will be easily revived once you warm it up.

The cutoffs you mentioned may be useful, and they may not be. If the cutoffs are still green then there is a good chance that the fungus is still active. If they're dry, you'll need to test them. Get a plastic bin with a lid and stick your pieces inside. Splash some tap water over the surface 2-3 times over the next week. After about 10 days, see if any mycelium is growing on the surface (it should be white. If its green, thats just a surface mold, and completely useless in terms of spalting). If no mycelium grows then your spores are probably not viable anymore. If it does grow, stick it in with some wood you want to spalt, and make sure everything is nice and wet.

Let me know how it goes!

Re: Spalt Your Own Lumber: Health problems associated with spalted wood, and debunking myths


I think you missed a lot of the main points in the article. The point I was trying to make was that spalted wood can be an issue, but the main cause of respiratory and eye problems in woodworkers is actually wood dust, not spalting. It is true that your spalted wood could have had some bad fungi on the surface that caused your eye condition. However those fungi were not DECAY fungi, the fungi that cause spalting. More than likely they were simply mold spores that landed on the wood from air circulation.

Not more than an hour ago I left a meeting with a top mycologist for the Forest Service. We discussed spalting and the possible toxic effects it could have. She brought to my attention that even those black mold spores were actually debunked as causes for the respiratory diseases that develop. In the end, the culprit was straight asthma and allergies, and nothing actually caused by the mold spores.

The issue with 'ask any doctor' is that doctors are not mycologists. Doctors are familiar with general practice, common conditions, and molds/fungi which cause diseases in humans. They are not familiar with wood-inhabiting fungi, which are the fungi we deal with when spalting. In this particular case, I would suggest that you 'ask any mycologist', especially those familiar with Basidiomycetes (wood decay fungi).

To everyone else who has concerns, I invite you to e-mail me at northernspalting@mac.com. I've sent out several very detailed e-mails over the past several months that list common spalting fungi, and links to scholarly articles which discuss their toxicity towards humans (or lack thereof). I stand by my statement that there is no special danger in working with spalted wood unless you have a compromised immune system (this includes asthma and many allergies!). I am violently allergic to wood dust (and all fine particulate matter) and many fungal spores, but work with spalted wood with no ill effects.

For more information on the general toxicity of wood dust, I suggest this article by OSHA:

Wurmm, I appreciate your concern, and would be happy to address any other concerns you may have regarding spalted wood.

Sara Robinson

Re: Spalt Your Own Lumber: Is it spalting? The case of the mysterious host-response color.


Yes, spalted wood is safe for food contact. As with any wood, spalted or not, the key is to keep the bowls dry. If they need to be washed, a wipe with a wet cloth and then a prompt drying will keep any new fungi from colonizing.

To be on the safe side, I would suggest you keep your stock in a rotation, where the ones you sell have been sitting in a well-lit room for 4-6 weeks before being used for food. Fungal spores can remain viable for quite a while and will grow again if given the option. However, this is not a phenomenon unique to spalted wood, as all wood has fungal spores on it, regardless of whether or not it is spalted.

I would also recommend changing your finish to a salad bowl finish or urethane oil. Wood in food contact should be treated with a penetrating finish that will seal the vessels and prevent cracking due to moisture changes. My two favorite finishes can be found at:




(both from www.woodturnerscatalog.com)

I'd be far more concerned about the fungal spores in your woodshop that you breathe in every day than ones that might get into your gut. Fungi require oxygen to survive, and the stomach is not only highly acidic, but also anoxic. Your lungs, on the other hand, are a little bit of a nicer area. But before you panic about that, rest assure that unless you have an immune deficiency of some type, the spores are no more harmful than wood dust.

I'm planning a blog entry on this topic soon, so keep a look out.

Re: Spalt Your Own Lumber: Introduction

nosepikr: I'm familiar with the beetle problems you guys have out there. Yes, that blue staining you see is spalting. There is some fascinating literature available on how the blue stain gets into the wood which you might be interested in reading:


Basically, the beetles carry the blue stain spores on themselves. When they infect a tree, the spores tag along for the ride, and get free access to the inside of the tree.

As for sealing blue stained wood, you have some decisions to make. Most spalting colors fade under direct sunlight. There are UV protectant finishes available, but most amber the wood. That isn't such a big deal if you're working with cheery, walnut or even maple, but if you're hoping to keep a strong color contrast on your white wood, you'll need to look elsewhere.

Personally, I prefer to use a paste wax for wood that will not be under heavy use, and a water-based polycrylic (many are produced by MinWax) for heavy use applications. Neither amber the wood, and both produced substantially fewer toxic fumes as you apply them.

Re: Spalt Your Own Lumber: Introduction

Mayonaise eh? I'm not sure I would recommend this approach, as none of the components of mayo are of interest to the fungi (except maybe the sugar). I'd be interested to see his spalting timeline when using mayo versus not using mayo. Anyone else tried this and had it work?

Re: Spalt Your Own Lumber: Introduction

Miserybob, those are a lot of long answer questions. If you don't mind, I'll save those questions and answer them in my next few blog entries. They deserve more time than a posted comment!

In general though, the spalting stops when you drop the moisture of the wood below a certain level (air dry is too dry for fungi). The fungus can't be active without water, so it is dormant. Finishing seals the spores into the wood and cuts off air flow to the remaining fungal hyphae (the 'roots' of the fungus), which also stops growth. Properly sealed spalted wood is perfectly safe for normal uses!

Re: Spalt Your Own Lumber: Introduction

Those white fans are known as a 'shelf fungus', and are usually great spalters! You should post some pictures of the fans and the wood. Some of the fans, like Trametes versicolor (Turkey Tail) are some of the quickest spalting fungi around.

Re: Spalt Your Own Lumber: Introduction

Unfortunately, there are a lot of fungi that can grow on roof shingles. Could you give me some more information so I can narrow it down a bit? For instance:

What type of wood are your shingles made out of?

What color is the fungus?

Does it form a fruiting body (mushroom)?

Unless you actually have the old type of solid wood shingle, I'm betting that what you have is algae, not fungi. Algae don't work for spalting, but they can certainly make your roof look pretty nasty!

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