# Drying in sawdust



## bikeshooter (Nov 5, 2010)

I had a conversation with an older gent at Woodcrafters today about some spalted gum I recently picked up. It is still too wet to put in a d/h kiln. My cheap tester is showing 35% and up on most pieces.He suggested putting smaller milled pieces in plastic bags and/or wrapping them in a tarp packed (emphasis on packed) with dry sawdust or planer shavings. He said it would be quicker that air drying and not as harsh as kiln drying. Seems sort of logical to me as a first step toward the kiln. Would appreciate any experiences or opinions from ya'll.

The pieces shown in the pics are 18" to 20" diameter and roughly 18" long. Also about the pieces shown, these were left on end and had no checking. I made a fresh cut and anchorseal caused the yellowish color.They have been down for about 18 months - some left on end and some on the bark. 



The tree fell over on a mans car - totaled btw. He had someone cut it into 18" pieces and just rolled them away from his house.


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## Daren (Oct 14, 2006)

I hope some wet wood turners see this, drying in sawdust is a more common practice with them.(maybe even ask in the turning section too ?) I hear it talked about a lot, just never do it myself. The sawdust part sounds right...but sealed tight in a bag/tarp where no moisture can get out doesn't to me. Pretty wood.


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## wmodavis (Dec 26, 2010)

*Drying - in general*

Here's what I think I know.

1) Moisture meters are not reliable at high MC readings hence most don't even display numbers above 30. But your reading does show quite wet wood.

2) Wood degrade during drying, whatever method of drying you use, is most likely at the higher MC readings. Therefore removing the moisture *slowly* at this stage is most critical. You can speed it up as the average MC gets down some. To slow it down use lower temperature, lower air flow and higher RH surrounding the piece being dried. But the ambient RH needs to be lower than the piece average 'Equilibrium RH'(ERH) or no drying will occur.

3) How slowly you remove the moisture to minimize degrade is dependent on wood species. Some can be dried faster than others without suffering.

4) Any dryer, if you can control ambient RH and monitor the piece MC, should work but me thinks those might be tough 'ifs', though not impossible, to achieve without getting more complicated than you want to. I don't think kiln drying is necessarily 'harsh' if air circulation, temperature and RH are controlled to keep drying rate slower then the species requires to minimize degrade. 

5) Most all of what the 'older gent at Woodcrafters' said seems to be geared to slowing down the drying rate so should/might work. Those methods won't necessarily allow you to keep the ambient RH just below the average piece enough to ensure drying at a rate to minimize degrade. But they MAY work, or they may not depending. The only feedback you get is likely when it is too late.

Looks like some beautiful pieces. Hope you can get them dry enough without too much checking.


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## Daren (Oct 14, 2006)

And I guess I forgot to ask what is your final planned use for this wood ? If it is mill it into ''lumber'' I would do that right now and not mess about with the sawdust and all that jazz.


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## slatron25 (Dec 18, 2007)

As a turner, we use wood shavings as opposed to sawdust. Everything I have read also says not to use plastic to wrap your pieces as it will promote mold and mildew we use paper. But the reason we do it is to slow down and even out drying not to speed it up to try and prevent cracking.


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## bikeshooter (Nov 5, 2010)

I appreciate the insight.

From another thread Daren suggested to mill to 8/4 minimum, kiln dry then go to 4/4 or whatever. I have a dh unit that I can control the humidity level. Perhaps I should set it to 50% or so and run it at night when the temp here in Florida is lower and turn it off during the day? Nighttime temps are around 80 for a low this time of year.

I also want to dry some 6" square pieces for some end grain inlay table tops. The sawdust option might work there. I'm not in a hurry to get this done.

There is some checking on the ends of pieces that were exposed to air - roughly 2 inches on most pieces. The ends that contacted the ground did not check. I'll be taking a fresh cut on the checked ends and sealing with anchorseal.


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## Daren (Oct 14, 2006)

That advice on milling/drying sweet gum you read was for fresh felled because it likes to move (twist mainly)...Spalted gum is tamer and a little easier to dry, I would just mill it slightly oversized. As far as drying ''lumber'' fast is best with gum. Stickers close, plenty of weight on the stack (mucho weight) and dry it fast. There is no advantage to letting the wood air dry before going in the kiln, and totally ignore the sawdust advice . It _may_ split, but if it is going to it will air dry or kiln dry, expect a little loss-just part of the deal with gum. It shrinks 15% from wet to dry (very high % for a hardwood, another reason to cut oversize) and is going to shrink the same amount no matter how it is dried, no getting around that and the problem that causes like splitting. 


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## dbhost (Jan 28, 2008)

On the turning aspect. I will turn a green bowl blank rough. Toss it in the, and you may laugh about this, but I toss it in the dust bin for my Thien separator. The sawdust / shavings that go through it are plenty dry, and tend to gently assist in the drying process. The concept of putting it in a sealed bag / plastic wrap sounds wrong to me... But I have known guys to do it. The idea is that the sawdust pulls the moisture, the plastic wrap keeps you from pulling it too fast...


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## bikeshooter (Nov 5, 2010)

Daren said:


> That advice on milling/drying sweet gum you read was for fresh felled because it likes to move (twist mainly)...Spalted gum is tamer and a little easier to dry, I would just mill it slightly oversized. As far as drying ''lumber'' fast is best with gum. Stickers close, plenty of weight on the stack (mucho weight) and dry it fast. There is no advantage to letting the wood air dry before going in the kiln, and totally ignore the sawdust advice . It _may_ split, but if it is going to it will air dry or kiln dry, expect a little loss-just part of the deal with gum. It shrinks 15% from wet to dry (very high % for a hardwood, another reason to cut oversize) and is going to shrink the same amount no matter how it is dried, no getting around that and the problem that causes like splitting.
> 
> 
> .


This advice is much appreciated and will we followed. You're the man Daren :thumbsup::thumbsup::thumbsup:


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## bond3737 (Nov 13, 2009)

just a thought, and I know perhaps this may seem unorthodox, but I used to do a great deal of gardening and was thinking that vermiculite would be a fantastic way to dry the wood and absorb moisture seeing as it is know and used for that quality. I dont know if anyone has tried it with wood for that purpose or not but I do know that if you want something absorbed (oil, chemical spills, water) vermiculite is the way to go... might be worth a shot???


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## ETWW (Mar 27, 2011)

When drying green turnings, it is common practice to bag them in a brown paper bag with shavings. That slows down the drying rate and helps to prevent cracking. The downside is that you must wait about 6-8 months for the rough-turned piece to dry.

Since your wood is already heavily spalted, I see no reason for packing the wood in sawdust or shavings. That will only help retain moisture and prolong the spalting process. You could easily end up with rotten wood instead of something usable.

BTW, air drying is much faster than packing in sawdust. There are three elements that determine drying rate...RH, Heat and Air Flow. For faster drying, lower the humidity, increase the heat and increase the air flow.

I don't know about Jacksonville but I always associate Florida with high humidity so a DH kiln is a good method of drying. 

The safe drying rate of Red Gum (Sweetgum) is 5.3% for 4/4 lumber and 2.1% for 8/4. I would definitely saw it first and then dry it.


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