I am in the process of building kitchen cabinets (1st attempt) out of birds eye maple. After building most of the doors I started the finishing process.. I put multiple coats on the front and only one coat of polyurathane on the back (thinking that it would be enough to seal out moisture absorbtion.) I am getting a pretty consistant warping on almost all of the doors (20) .. this summer has been REALLY humid in NH.. and my guess is that the fact that I put different thicknesses of Polyurathane on the wood is what is creating this issue. I am thinking that I will proceed with the installation.. and this winter when the wood stove drys the doors out .. they hopefully will return to an acceptable form at which time I will equalize the finish by adding additional coats to the back of each door… Any thoughts..
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Replies
Pete,
Your right about the miserable summer up here. Can you provide more detail on the door construction..size, style, etc. and where the warping is occuring. Thanks
BG.. thanks for your response-
The doors are about 28 inches tall.. by 12 inches wide (Average, there are some that are larger)..
the construction is frame and panel where the panel is flat (going for somewhat of a shaker style)... I left the panels the full thickness and the back of the panel actually projects 1/4 inch into the cabinet.. The maple is 14/16 thick (long story)- In most cases, the panels are a single piece of wood... I only had to glue up a handful of panels for some of the wider doors.. interestingly enough .. those doors have not had AS MUCH of an issue...
The rails and stiles are 2 inches wide and the center panel has a 3/8 X 3/8 tongue that fits into the frame... the panels are free floating (no glue)..
When the doors are mounted in the face frame one corner projects outward... in most cases its around 1/4 inch -
Pete
Well, Pete, I only put one coat of varnish on the back side of all my word and I can't say I have that problem even in Florida. Varnish isn't going to prevent moisture absorption over the long term, but merely slows the rate down. Testing shows that almost no finishes except linear urethane (Awlgrip) are impervious to water vapor. Anyone will have the problem when the wood you are using isn't stabilized to your ambient humidity, especially with long rails and stiles cut from large boards. I buy a lot of wood from Wisconsin where the humidity is a lot lower than where I am. To avoid the problem I have to let the wood sit in the attic for three months and stabilize. Then I end up scrapping half of it because it becomes unuseable due to warpage.
Your wood could also be slightly reactive, compounding the problem. Otoh, figured maples can be very reactive. You relieve the stress when you cut it, but it continues to warp after you flatten the piece. The only solution I know of is to wait a couple days after cutting and before assembling to see how it behaves.
I agree with "none" about the cause of the warping. I don't think that it has anything to do with the "unbalanced" finish.
Do you have any scrap rails and stiles from the project lying around? Are they showing any warp?
Rich
Hi Rich,
Yes I do have some scrap rails and stiles.. 2" widths.. The majority are not showing notable warping- actually, I cant think of any that are--some of the wider pieces (8-9") have shown some warping... but not consistant.. and only on a few pieces.. The thing that confounds me is that the amount of warpage is relatively consistant on the doors-
Do you think that it will move back at all when the air dry's out?
Thanks for your response
Pete,
I don't think that the doors will return to flat, although they may move a little, they may get even worse when the ambient humidity goes down!
I think you may be dealing with a case of mild 'case hardening,' which if true is non-correctable. The doors may have warped as a consequence of your cutting and working the wood. The scraps may not have warped as much because you didn't work them as much.
I still don't think that the unbalanced finish is the cause, but you might test this by finishing one of the scraps, without further working it, or try working and smoothing a scrap without finishing it.
Sorry, but I don't think the the doors will flatten on their own, or will stay flat.
Rich
How are the doors warping? twist? cup?
When did you first notice it?as they were assembled or over night?
Jim F.
Jim,
I believe you meant your message for Pete.
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