Proper MC for Maple, Ash

[john moorhead]

Folks -

I have to make some fairly substantial cutting boards out of maple and also ash. I don't want the glue ups to open up and was wondering what the proper MC should be. The maple is reading 13% and the ash is about 11%. I was thinking I should have them both under 10%, but am wondering if it would be better to put them in a warm place and try to get it down to say 6 or 8%

I am doing my glueups out of 5/4 stock. What'cha all think - biscuits, dowels or straight edge gluing. Also would gorilla glue rather than Titebond II be better for this application?

TIA

John Moorhead Lakeport, CA

[James D Kountz]

I always try to get my stock down under 10 perferably 8-9 if at all possible. When I first started woodworking I never paid attention to things like that and now I have some 20 year old furniture in the attic with cracks and splits and drawers that dont fit anymore. Live and learn!

Jim

[George]

Whether or not the joints open up on a simple unrestrained edge glue depends on _relative_ movement, not on MC. That, in turn depends on the grain orientation, species, and washing/storage conditions.

Edge gluing is more than sufficient, but water-resistant glue is a great idea.

[George M. Kazaka]

Before you start worrying about Moisture content, where do you live, that is what determines the acceptable moisture content in wood. If it is Kiln Dried properly they take it down to at least 6% I have also heard of 4% When I was in MD the best wood would check in at is about 12% it is worse in Florida and Houston and other high Humid area's, Here is AZ in the summer we have to through a bucket of water on it, We have day when the Humidity is as low as 4%

I had a map that showed the acceptable moisture of wood in different parts of the country Be damned if I know where its at but have a hunch and will look for it tomorrow

George

[Preston Andreas]

Fortunately, ash and hard maple aren't real far apart when comparing shrinkage to moisture content. Since cutting boards are unfinished, they will have a wider swing in moisture content than finished pieces. The more important considerations are that the boards are close to equal in moisture content before glue up and the moisture content is somewhat near the average moisture content. Another consideration is to make sure the glue you use is water resistant or waterproof. I think the moisture content is close enough for glue-up. Use polyurethane glue or even better, epoxy. If you use epoxy, make sure you don't over clamp the glue-up.

You don't need biscuits, dowels or anything but straight edge gluing if your equipment can mill the edges good enough for a good glue fit. Dowels, biscuits, etc. only give alignment.

Preston

[George]

R. Bruce Hoadley - Understanding Wood

I think there's one in the drying or storing literature on this site.

as I said, as long as there are no outside stressors, doesn't matter.

[Scott Post]

Ignore any answer from someone saying "wood always has to be at X% moisture" unless they live in your town and their shop is of the same type as yours (a garage or an airconditioned/heated interior space). The moisture content stabilizes to a different value depending on your environment. In my neck of the woods in my dehumidified basement shop wood stabilizes to 8-10% in the winter and 10-12% in the summer. Doesn't matter whether is was kiln dried to 6% or air dried to 14%. The best thing to do is check a few pieces that have been in your shop awhile to get an idea what moisture content wood stabilizes at in YOUR shop at the same time of year.

Last month I picked up a couple loads of wood, some air dried and stored in an unheated barn and some kiln dried and stored in a heated room. The air dried stuff was a few % wetter (it was at 12% if I remember right) than the kiln dried stuff. Within 3 days of bringing it into my shop both had stabilized to the same moisture content of other wood that's been in my shop for a couple years (9% if I remember right). It wouldn't hurt to give them a week or two just to be sure.

Straight edge gluing. Dowels weaken the joint (they're cross grain) and biscuits don't add anything but an extra step. I use polyurethane glue for cutting boards. Don't have any experience with Titebond II so can't really say.