The Woodworking Life

Spalt Your Own Lumber: Introduction

Sara Robinson, member

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Hemlock wood turning with pink and yellow spalting

Pink stain is most often caused by Arthrographis cuboidea, but that yellow could be any number of fungi.

That Athrographis has pretty much taken over one of my tubs, and I keep pulling out piece after piece of pink wood!

Hemlock wood turning with pink and yellow spalting

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Greetings!  Some of you may remember me from an article in FWW last summer, DIY Spalting (from FWW #199). My inbox has been pinging non-stop since the issue hit the shelves, and I have to admit that I have been overwhelmed with the response.  So, I'd like to introduce myself to all of you and continue to share my spalting knowledge with the FWW family.

As you may (not) recall, I'm a PhD student at Michigan Technological University researching spalting.  Spalting is when fungi color wood (not when the tree does it alone), and can come in any color you can imagine.  My current research focus is on color stimulation, but I've done a lot of preliminary work on the actual spalting process.  I actually spalt wood in my bathroom using big plastic tubs and vermiculite as a moisture control.  I've spent the past several summers collecting fungi and documenting their color contributions to spalting.

Spalting tub. Robinson inspects the spalting pattern on a sample block.

MORE ON SPALTING

Summer is right around the corner, which means the mushrooms will be peeking up through the duff in a few months.  I hope to bring you photos of some of my favorite spalting fungi, along with examples of their work on various wood species.  I'd also love to answer any of your spalting questions, and would love to hear about (and see) some of your spalting triumphs (and frustrations)!

For today I'll leave you with a piece of hemlock with my favorite spalting color combination: pink and yellow. Pink stain is most often caused by Arthrographis cuboidea, but that yellow could be any number of fungi.  That Athrographis has pretty much taken over one of my tubs, and I keep pulling out piece after piece of pink wood!

Sara

Got questions about spalting? Post a comment below.

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Comments (22)

clickerflicker writes: I will certainly try the test. If it appears to be spalting then I will get in touch with you. I believe that it is not spalting. I used a desk wash product that contained an oxalate in sodium hydroxide and it also caused the stain. I suspect that the oxalic acid is chelating the red color bodies in the cherry wood and solublizing it. That appears to explain the streak marks. If I used the same cleansing cloth on my birdseye maple that I did for cherry I could have transferred the color bodies.

The question is whether other common chelators such as citric acid, ascorbic acid or ethylene diamine tetraacetic acid might be better? I would want a chelator strong enough for copper, nickel, and iron but too weak for the cherry color bodies and is still water soluble. I just don't have the chemicals available for all the testing.

Here is a new product for you. Chelate the cherry color bodies and apply the resulting mixture as a cherry stain on other woods. The mixture would not be subject to photoxidation but would only darken over time. That would beat any organic dye currently on today's market.
Posted: 1:30 pm on April 12th

Dr_Spalting writes: 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.
Posted: 1:38 pm on April 9th

clickerflicker writes: The workshop abuts fencing that has been treated with a copper preservative. The fencing has a green mold or fungus on the fence board sides. It has a black fungus on the fence board and post ends that are exposed directly to the rain. While the lignins in the ends have obviously been removed from the weathered ends; there is no visible spotting on the fence boards / posts. There are also diseased cherry trees on the property that I have not bothered to cut down and burn. Article was interesting.
Posted: 1:07 pm on April 5th

clickerflicker writes: I use a hot water bath only for bending these thin <= 1/8" veneers. The water bath temperature is 127 deg F to 145 deg F and a clean bath is used on each day's new bending. If I am doing multi-species bends it is birdseye Maple then Maple then oak then walnut then cherry. I do so because it is reputed that cherry will stain other woods; although I have not observed this. The oxalic acid bath is about two tablespoons per five gallons of water. Woods may be kept in the water bath 20 minutes to 2 hours or longer. While the copper deposits show up within hours or less, the red coloration may take a week or longer to develop. I only notice the coloration once the wood is dry. The coloration can not be sanded out of the wood, although it does not completely penetrate a 1/16" veneer. The coloration darkens over time. When the stronger 3% solution of oxalic acid is applied to dry wood to remove the metal spotting, the red color may or may not appear. Although that could be due to how thorough I rinse the wood. The workshop is a high dust environment with many different wood species. This winter the bentwoods are taking longer (2-3 days) to dry to 11-15% moisture. As a result I have been seeing green mold on the bent boxes. Exposure to light, air movement, and sanding gets rid of the mold - still its a pain.
Posted: 12:41 pm on April 5th

Dr_Spalting writes: 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:

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VG6-414WX26-B&_user=994540&_coverDate=07%2F31%2F2000&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1276607162&_rerunOrigin=scholar.google&_acct=C000050024&_version=1&_urlVersion=0&_userid=994540&md5=0bda003667e14e6b5813356b04d2061e

As a mordant:

http://en.wikipedia.org/wiki/Mordant



Posted: 3:27 pm on March 31st

clickerflicker writes: I am a Shaker box maker. I hot water bend cherry, walnut, and maple woods. The hot water bath has oxalic acid added to prevent metal spotting. Upon occasion cherry and even less frequently my birdseye maple bands will develop a pink splotching. It looks remarkably like your spalted hemlock bowl. While the splotching is generally irregular in shape, it sometimes appears to be almost straight lined across the grain. If I do get metal spotting I use a 3% solution of oxalic acid to remove the metal spotting then rinse with clean tap water. I would say that 90% of the coloration comes when I use this 3% oxalic acid solution. It takes the pink color 10 days or more to develop and will continue to develop color even under a 5 coat nitrocellulose lacquer. Do you think I have staining or spalting? Do you have any possible cures for either? I can sell spalting not staining.

Since I have tried everything a chemist could think of to remove staining I am leaning towards spalting. Especially since I have found this pink color on birdseye maple. My guess is that the 3% oxalic acid is promoting the spalting.


Posted: 11:46 am on March 30th

Dr_Spalting writes: 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!
Seri
Posted: 9:20 am on May 24th

mvealey writes: Is there a way to save or store different fungi for use later? I don't do a lot but every now and then it would be good to have everything on hand so I can start spalting a piece for a specific project.

Also, what about using cutoffs from wood that's already spalted? I recently made a jewelry box with a spalted maple top and I have a lot of shavings and small cutoffs. Are they useful as sources for fungus?
Posted: 10:42 am on May 14th

Dr_Spalting writes: 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:

http://www.colostate.edu/programs/cowood/library/Blue-Stain/Blue_Stain_markup.pdf

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.
Posted: 9:40 am on April 18th

nosepikr writes: i live in Colorado and we have--unfortunately--an abundance of pine beetle killed pine wood.
--is the blue staining "spalding"
--any suggestions for staining, sealing, etc this wood when i make furniture of it. i want to maintain this beautiful color.
thanks
Posted: 5:31 pm on April 17th

Dr_Spalting writes: 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?
Posted: 2:36 pm on April 17th

waterwax writes: Sorry, I forgot to say that I had a lot of cherry burl and other woods in the basement for turning. My basement flooded because the sump pump became disconnected. One or two inches was enough to spalt some cherry burl and others since the humidity was so intense and of course it was dark. As to spores, I had other spalted blocks like buckeye burl. I was letting the wood air dry and then the flood. Most were still waxed but in 2 years I was amazed and upset same as the day of the flood. Nevertheless this is not recommended. But it can happen to you too. Maybe I juggled an idea for DIY. I hope so. Just wish to help anyway I can. I thinkthe farmer rapport is best earlier posted. You might find 50 acres plenty and not to be overlooked. Again good luck.
Posted: 1:39 am on April 17th

waterwax writes: I have to give Sara Kudo's for her work! Now to share with fellow saw dust makers, I lived on a farm some time ago andwe had quite a woods canopy where little light came throughand there was a lively creek. So every now and thenafter as thunderstorm, new felled trees were marked. Many types of mushrooms grew on already too spalted soft punky woods. In fact there were many patches of mushrooms dotted here and there. We had maple, Oak, Locust, Hackberry, and most anything one could wonder with 116 acres. One maple in particular was over 200 years old that got nailed by lightning and within time it spalted. The ground was rich (never tilled--how could it be?) there were trees of differing sizes every 2-3 feet making night crawling and getting back home a navigation nightmare. There were plentiful leaves and they were deep making the ground moist. What I am trying to convey is that if you are an avid hunter ask to hunt on a farmer's land and return often. Give them money, jelly, blueberries as tokens for their time. Flag the trees somehow with a map you draw. Don't put a flag on a desireable tree. Start up a conversation and then talk about your hobby of hunting and woodworking. Then eventually ask the farmer if you could get some old decayed wood that you can use and you would like to haul it out even by hand and rope or a long winch and even prepare toask to pay for it. Chances are if you are on his good side with a good rapport you get it free. Our family did not have use for such huge supply of spalted wood. We used locust for fence posts and one guy helped us out for a few hours.--Priceless. The DIY way of spalting is unpredictable and complicated. But Sara as a scientist showed us a method with her work and very generous to share. We had native elderberries people picked for wine after we were done, same with ginseng, blackberries, walnuts, and more. We had cattle so I buried wood inmanure for awhile and then washed it off. Years later I saw Adventures in Woodworking and found George Frank did the same. We had bee hives so we had plenty of Bee's Wax. We didn't know any woodowrker(s) but candle makers picked it up for free. Just to let you know there is rich land on farms with much to offer in abundance and to earn their trust and friendship will pay off in many dividends. We had bumper crops and bartered whether fresh or canned. One thing we didn't take a liking too was people trespassing on our land. If they were hunters we chased them off due to safety since I hunted. I didn't like some idiot shooting at me and I retaliated in kind being a marksman getting closer to him with my bullets than his bullets shot at me. Always wear a bright orange vest and ask whatever your real purpose is and strike a good accord. You just might make some real decent friends and get some venison too! We sold the farm and ever since I regretted my father's decision. Sorry for the longevity of my post. Good Luck!
Posted: 1:26 am on April 17th

SPWoods writes: On reading this article I thought I would relate a recent experience drivimg up through Northern California to Oregon on a return from vacation along the coast route. I stopped at place selling burls, the guy started telling me how he gets wood to spalt using mayonaise. I didn't get all the details as I was not interested in spalting my own wood. I think the gist of it is that he slathers it on logs after they are cut, then puts the slabs back together loosely, then leaves them to spalt. (I don't know how long) He said he buys the mayonaise from a restuarant supply company.
Posted: 12:53 am on April 17th

Dr_Spalting writes: 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!
Posted: 9:52 pm on April 16th

miserybob writes: Very interesting articles, Doc, great stuff!

After you've let the wood lie in the dark with the fungus and spalt, you take it out, brush it off, let it dry and plane it... Does the spalting process stop on its own? Is the fungus still active in the wood? Does the finishing process kill off the fungus?

Thanks!
Posted: 9:43 pm on April 16th

Dr_Spalting writes: 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.
Posted: 9:18 pm on April 16th

patchjob writes: Hey, cool. I think between the original magazine article and some cabinet panels i saw, I was inspired to let a ~48" x 20" chunk of beech trunk sit around in my yard for a while. Some little white fungi fans grew on the bark, so I figured it was time.

I cut it into slabs on my bandsaw, and the spalted pattern turned out pretty nice. Now I'll hopefully be able to turn it into some cabinet panels of my own without screwing up...
Posted: 8:54 pm on April 16th

boomhauer writes: Doc, glad to see the blog up and going. Looking forward to reading more from you.
Brady
Posted: 4:54 pm on April 16th

flagship writes: Your right that is algae.
Posted: 9:47 pm on April 15th

Dr_Spalting writes: 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!
Posted: 7:27 am on April 15th

flagship writes: I would like to give spalding a try,there is fungi on roof shingles are you formiliar with that?Randy
Posted: 9:53 pm on April 14th

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