Woodturners of south west florida
Tips: Spalting
Taken from rec.crafts.woodturning

Subject: "Custom Spalting"

Can you custom spalt a turning? By that I mean if you have turned an item, say a bud vase from dry maple, can you put it in a bag with high humidity and cause it to spalt?  Presumably you would need a piece of spalted wood in the bag to "inoculate" the new piece.  If this would work the spalting could probably be controlled as to depth of spalting and
minimization of wood rotting and becoming punky. 

If no one has tried this, comments and suggestions of how to proceed would be appreciated. 
Could be an interesting project. 

Bob, London, Ont., Canada 

The internal MC of the wood will have to be above 20%. @05 is the magic point at which microbial growth ceases in wood. This means that your turned piece at the end of spalting will be subject to all the problems of drying.  So, you need to rough turn first, spalt, then clean it up again.

Simply keeping the piece at or near FSP (28% MC) and at room temp will virtually guarantee microbial growth.  We used to do this to try to create rotten wood in the lab. Worked very repeatably.  Any wood with residual sugars like maple seems to give better results, color-wise.  In about 6-8 weeks you will have a fairly serious culture of microorganisms going. In 6-8 months you will have a lot of sponge, not wood.

The method:
1. hold the piece of wood (we used blocks 4"x4"x4") underwater for about 48 hours.  We used softwoods and red oak.

2. remove from water and keep piece in a chamber (like a terrarium) with humidity at or near 100% all the time.  We use dirt/peat moss floor saturated with water.  The microorganisms need air to grow.  Add water about once a month.  Keep a glass top on the chamber, and allow a small amount of air exchange with the outside world.  Light causes a lot of algal growth which is basically neutral to what you're doing.  Dark creates mostly the white fuzzies.

3. Pieces get fuzzy in about 6 weeks.  Reddish clumps are often slime molds which are kinda interesting, if you're into Biology at all.

4. you are on your own after this point - we just kept the wood until it was like sponge.  Sometimes we got interesting colors in partially rotted wood, other times not.  I can't say how long to leave your pieces - probably not too much longer than when the exterior molds begin to show up - like 6-10 weeks.

The down side is that other kinds of microorganisms get in the way.  We almost always got the "greens" in oak, which isn't very attractive.  At least in my opinion.  And a lot of times we just got paler wood or punkiness.  You cannot predict what'll happen.  But you will get microbes of many different flavors going.  Therefore it doesn't seem like a good plan to
spend $20 on a bowl blank, turn it, try to spalt it, get horrible results.  Turn and practice spalting on something close to free.  I expect the failure rate could be kinda high.

I guess someone should develop an innoculant for deliberately spalting wood.  Select it for color, etc.  Wonder if you could sell a spalt-a-wood kit?  Hmmm.  Not me.

jim mcnamara
domingo rose

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An Interesting Story...from rec.crafts.woodturning

Most of us, from time to time, like to turn spalted timber. The unique patterns created can be quite provocative and add significantly to an otherwise plain figured timber. The problem is getting the log spalted enough to have great figure, (fine black or other colored zoned lines) without the log being "too punky"

I have tried to spalt my own timber in an effort to control the amount of degrade and to cut the logs at just the right moment. You want the color and figure to be good, but the structure of the timber to still be sound. This is not an easy task, as anyone who has tried this can attest. 

I have tried various home spalting brews, (what a waste of a good stout) magic potions, other world chants and the like, to speed these puppies on to spalting heaven. Sometimes it worked and other times it was a dismal failure. Most of the spalted timbers I have been lucky enough to find already spalted, have been too punky for a production turner like
me to waste time with. The thought of spending a hundred dollars for penetrating epoxy to stabilize a vase seemed just too much.

Therefore, on some recent Pecan logs that I have been turning (and turning and turning and turning, gasp!) I decided that I would take a different approach. I coated the endgrain with a wax emulsion sealer and stored the logs standing on the end in the non a/c'd part of the workshop and forgot about them. I have had enough of rotating logs in the dirt! Here in the heat and humidity capital of the universe (Houston, Texas USA) it gets bloody hot and humid during the summer. In fact, it stays that way ALL summer long!!!!! Arghhhhhhhhhh!

On the theory that a watched pot never boils... I forgot about these logs for about three months or so. When I began chainsawing them into bowl blanks a few days ago...Wow!, magnificient spalting! Clearly defined zone lines with superb color and all without potions, chants or prayers to the spalting gods. In fact, I did nothing other than coat the
endgrain and stack them in the corner on the epoxy coated concrete floor. Now this is a process that I can really get into!

The high heat and humidity around here is finally good for something, other than turning my electric bill into another house note. :-( Those of you who live in cool, low humidity areas (like I dream of daily)... it's back to the dirt and potions for you! 

Letting the chips fly...
Steve Russell
Eurowood Werks Woodturning Studio
The Woodlands, Texas

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