Storing Maple in Partially Dried Condition

A woodworker gets advice on the feasibility of maintaining wood at 25% moisture content for use in drying operations. January 8, 2010

I buy green hard maple and dry it about halfway for use in bending operations. My target is 20% to 25% on stickers, then I dead stack it and store it wrapped with tarps to hold that moisture content (which I need for good bending). Yes, I do get a little color degrade from storing it, and sometimes a little mold, but it isn't usually that serious as it gets re-sawn and planed before use. I source the green maple in the winter, and am just about to set up a larger than normal green batch for the season. It needs to supply my production needs through the summer and early fall until hard maple is logged and sawn green again.

I've used a simple pre-drier in the past to partially dry hard maple with a dehumidifier, kiln fans and a little heat (about 20 F over the ambient outdoor temp.). It takes only about a month to pre-dry 5/4 hard maple this way. I'm wondering if outdoor stickering with good airflow and a cover to keep rain off will do just as well. I'm not in a hurry to dry it, though I do understand there can be some color degrade from slow drying maple. I don't have a strict color spec on this hard maple.

Gene, I recall that you said once in a forum (or maybe I read it in one of your books) that hardwoods will store well at 20% and below. Would you think that this should work ok with hard maple? If so, could I push the MC? Maybe to 25%? What conditions would best prepare the hard maple during pre-drying and subsequent storage while half dry? In particular, should I keep it stickered during storage (20 to 25%MC) rather than dead stacking? That may allow it to dry further though, and it I consider it spoiled for my needs if it gets much below 20%. Also, I'll probably get sticker stain, but again, maybe not serious because it will be planed before use.

Forum Responses
(Sawing and Drying Forum)
From contributor X:
I'm not a maple guy, but since I know what you do with the wood I'll throw out an idea. I don't know what kind of quantity you're talking, but if it isn't 10s of K BF maybe you can manage to keep 2/3 to 3/4 of them in limbo. What I mean is, do you have the means to keep a large portion of the boards submerged in cold or cool water, and remove them for drying in phases, timed with your pre-determined needs? I can only assume maple will not degrade any more than other species submerged even though not in log form. In fact, some of the most expensive wood you can get is curly maple which has been submerged in the great lakes for a hundred years or more.

From contributor Z:
It's about 1000 bd ft. at a time. Interesting idea probably not practical for me but something to think about. I'm thinking more of keeping them in limbo at 20%, and try not to get too much stain, but I understand your point of holding it at a higher MC.

From Gene Wengert, forum technical advisor:
At the high MC, it is possible for mold to grow. You might try a brief heating period to kill the mold and other fungi, but if air contacts the lumber the mold could grow again. You could store the wood in a refrigerator (under 50 F) and that would keep things under control although it might cost a bit more than you can afford.

From contributor Z:
I have noticed that if I bag the 20%MC hard maple and seal it well, I don't usually get mold growth. However, if I just dead stack it, mold may take over.