What is Spalted Wood?

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As a woodworker, I am always looking for unique woods to work with and sell. These may be highly figured woods, burls, or spalted woods.

I love working with spalted wood as every piece is unique, and often the wood is otherwise inexpensive.

Something that also draws me to working with spalted wood is making it myself from an ordinary piece of wood. We’ll discuss this in-depth, as setting up your own spalting pile is a fun way to start creating your own spalted wood.

What is Spalted Wood?

Spalted Birch Wood Bowl
Spalted birch bowl

Spalted wood is wood that has begun to decompose from fungus or bacteria in the wood. This natural decay can turn an otherwise ordinary piece of wood into a beautiful showpiece.

As the fungus works through the wood, it will initially show up as dark blank lines. These will be extremely thin, almost as if someone has drawn pen lines throughout the wood.

As the decay further spreads, the wood itself will begin to show signs of rot and decay. This will lead to soft or crumbly wood that will be difficult to work with without stabilization.

Spalting can occur in almost any variety of wood, but it is most often sought after in lighter-colored domestic species like maple or birch. These woods tend to spalt easily and show off the dramatic spalt lines the best.

Where to Find Spalted Wood

Finding spalted wood to work with can be tricky as most commercial lumber suppliers don’t put much value in lumber that has started to decay! This leads to them tossing spalted wood in the burn pile rather than mill it up into smaller blanks for woodworkers.

Luckily, there are still plenty of great options for finding spalted wood! Or if you’re feeling adventurous, you can even make your own!

Firewood Piles

Firewood piles have been the source of some of my favorite pieces of wood I’ve worked with over the years. These spots, especially the messier piles where wood may be laying on the ground or covered in leaves, can create the perfect conditions for spalting.

If you live in an area where maple, oak, ash, cherry, or birch grow, then poking around any firewood you come across may provide some surprising results.

I like to watch sites like Facebook or Craigslist for people advertising free firewood. Often this will be wood rounds from a recently cut tree they have put out on the curb and want gone. If the tree was taken down by rot, then there is a good chance the wood will have some spalting already in it.

Where to Buy Spalted Wood

Local Sawmills

Some good places to buy spalted wood are local lumber mills or backyard sawyers. These businesses will usually understand what woodworkers are looking for and will set aside unique pieces such as spalted wood.

I frequently buy from a woodworker who runs a chainsaw mill in Portland and have picked up some beautiful spalted birch and applewood blanks. He works with a lot of woodturners, so he is always setting aside small spalted blanks.

Mature trees in urban settings are often brought down due to rot setting in. This can lead to instability in the tree or result in it falling on its own. With this internal rot comes spalting, so finding local folks who mill these trees will be a great local source for buying spalted wood.

Online

Specialty wood dealers will sometimes carry spalted wood blanks, although they can be, at times, difficult to find.

For example, I frequently shop at Goby Walnut out of Portland, Or. Goby specializes in wood harvested in the Pacific Northwest and sells slabs, lumbers, turning blanks, etc. at their warehouse and online.

While they don’t explicitly have a spalted wood section, you can often find a wide variety of spalted wood blanks and slabs by searching for “Spalted” on their site.

Etsy is another surprisingly good option for buying spalted wood blanks.

 Spalted Maple Pen Blanks by CurlyWoodStore

There are a TON of sellers on Etsy who cater to woodworkers by selling prepared wood blanks in various species and sizes.

My favorite part about buying spalted wood blanks from Etsy is I can often find blanks that have been stabilized. Stabilizing wood is a process that involves soaking wood in a stabilizing resin which, when fully cured, results in a wood that is extremely hard and durable.

Since spalted wood can often have soft spots, this makes the wood more workable for high-use items like pens or pepper grinders.

Making Your Own Spalted Wood

One of the coolest things about spalted wood is you can make it in your garage or backyard! All you need to get started are some rough wood blanks of some of the woods we discussed earlier. You can begin with thick boards, half rounds, full rounds, etc. As long as the piece is thick enough not to warp and crack too much after drying, then you’re good to go.

To induce spalting, you’ll want to have a spot where the wood can stay warm and moist. This can be a trash bag, a large plastic tub, or a pile of leaves with a tarp over the top.

Place the wood inside your container, cover it with wood chips, leaves, or sawdust and add some water to keep everything slightly damp. Loosely cover (the fungus needs air to breathe and spread), and you’re done.

After a few weeks, you can begin checking the wood for signs of spalting. That’s it!

Once your wood has finished spalting, you can bring it back inside to begin drying out. The fungus spores that resulted in the spalted wood will go dormant once the wood has dried, so there will be no risk of further rot or decay.

How to Work with Spalted Wood

Working with spalted wood will vary depending on how far along the wood was in the spalting process. A lightly spalted wood will work the same as a comparable piece of non spalted wood.

Conversely, a deeply spalted wood that has begun to show signs of rot may have numerous soft or punky spots that require some serious prep work.

In softwoods like birch, the line between lightly spalted and rotten can be crossed pretty quickly. I’ve opened up a few bowl blanks only to find that they are way too far gone without some serious stabilization.

That brings us to…

How to Stabilize Spalted Wood

Learning how to stabilize wood is an important arrow in the quiver of any woodturner. Stabilizing wood involves soaking it in a heat-activated resin under a vacuum, so the resin is pulled into all the softwood fibers. Once heated, the piece will be extremely hard and durable enough to turn into high-use items like pens or knife scales.

With spalted wood that has started to get punky in areas or when working with very softwoods like birch, this is a great way to produce beautiful wood blanks. You can also use tinted resins to create unique, colorful wood blanks that will stand out in your workpieces.

There are only a few items needed to get started with stabilizing spalted wood.

  • Vacuum Chamber
  • Toaster Oven
  • Cactus Juice Resin
  • Aluminum Foil

Step 1: Dry to the wood

Your wood needs to be as dry as possible before beginning the stabilizing process. Wet wood will lead to improper resin absorption, curing, and will not be as stable as a finished product. Ideally, you’ll want to shoot for moisture levels below 5%.

A few hours in the oven at a low temperature should be enough for smaller blanks.

Step 2: Load the Vacuum Chamber

Place your wood blanks directly inside the vacuum chamber or a holding vessel. Ensure there is plenty of room to add at least an extra inch of resin over the top of the wood as the resin level will drop as the wood absorbs it.

Note that the resin will appear to boil during the vacuum process and may foam up, so leave plenty of space so the resin doesn’t foam over the holding vessel or the top of the vacuum chamber.

Pour in the resin, optional tinting, and turn on the vacuum. Once the wood stops bubbling, the process is complete. This usually takes between 30 minutes to an hour.

Step 3: Wrap and Bake the Wood

Once the woods have fully absorbed the resin, they can be removed from the vacuum chamber.

Wrap them tightly in aluminum foil and place them in a toaster oven at a temperature around 200 degrees. Bake them for 75 minutes and remove them to cool.

The stabilized spalted wood blanks should now be fully cured and ready to use in your next project.

Finishing Spalted Wood

Spalted wood is effortless to finish as it can be finished just like any other wood so long as it isn’t very punky.

Some softwoods like spalted birch can be susceptible to splotchy finishes as the soft parts of the wood will quickly absorb large amounts of finish. In these woods, I recommend using a hardener like CA glue or creating a solid surface that will hold the finish better.

Minwax wood hardener is another option for firming up punky wood. This product is marketed primarily to repair windowsills or other areas around the house with minor water damage. It works perfectly well on woodworking projects also.

My favorite finish for spalted wood is wood butter made from mineral oil and beeswax. It leaves a lovely natural finish that is food safe and easy to reapply as needed.

Is it Safe to Work with Spalted Wood?

I have found that working with spalted wood has been no different than being exposed to ordinary wood dust. As there are microbes in almost any air-dried piece of wood, exposure to those same microbes in spalted wood isn’t any different.

Still, I always wear a dust mask when working with any wood and use both a dust collector and overhead air filter to help keep the wood dust to a minimum.

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