grrr My first exprience with wood movement

[fourleafandy]

Hello Everyone,

As some of you may all ready know i am fairly new at wood working, and just lately i have been practicing on small projects to hone my woodworking skills.

I decided to make a fish tank hood and silly me brought some pine from Big B's which looked straight by eye but when i got it home was slightly cupped. well i decided that i would have to make do with it and it was only slightly cupped. I made the lid and added a molding to it which i used a router with a straight bit to make it all the same level around.

I added varnish to it which contains a clear coat and left it to dry and low and behold the lid seems to have straightened itself out which has made the molding drop away. Not sure how i am going to fix this and I'm to embarrassed to take a picture to show you guys :B

Thank you for reading my post, hope it made sense.

[BrettC]

Shouldn't be too much drama to just rip the moulding off and redo...:doh:

[weisyboy]

make sure you seal it well underneath. the moisture will make it move like buggery.

[Harry72]

You can reattach the molding now the wood has moved, it'll need to be sealed pretty well being above water.
Dont worry radiarta pine will do that(not just the bunnies stuff), it depends on the grain structure. If you give us a pic we may be able to diagnose why.

[Skew ChiDAMN!!]

Yeah, all wood will do that to some degree or another.

Being over water, you really need to seal it well, inside & out.... and even then it'll still move over time. The only "real" solution is to design with the movement in mind.

Pix (or even a sketch) of how 'twas constructed will allow more detailed replies.

[joe greiner]

I sounds like you applied varnish to only one side. Shrinkage of the drying varnish probably pulled the top out-of-plane.

Whatever you do on one side of the material should be duplicated on the other side, to equalize shrinkage effects, and prevent bowing. This is a trick used by water-colour artists: When attaching a painting on water-colour paper to illustration board, glue a blank sheet of the same paper on the other side, at the same time. The liquids of the glues, in combination with the papers and the board, maintain equilibrium throughout the process of drying, and the assembly remains flat. The same trick can be used with veneer constructions, applied felt, and so forth.

You may be able to strip the varnish, and allow the wood to re-find its natural state, before fixing it all. The moulding may be re-usable without too much added attention.

Cheers,
Joe

[fourleafandy]

I sounds like you applied varnish to only one side. Shrinkage of the drying varnish probably pulled the top out-of-plane.

Whatever you do on one side of the material should be duplicated on the other side, to equalize shrinkage effects, and prevent bowing. This is a trick used by water-colour artists: When attaching a painting on water-colour paper to illustration board, glue a blank sheet of the same paper on the other side, at the same time. The liquids of the glues, in combination with the papers and the board, maintain equilibrium throughout the process of drying, and the assembly remains flat. The same trick can be used with veneer constructions, applied felt, and so forth.

You may be able to strip the varnish, and allow the wood to re-find its natural state, before fixing it all. The moulding may be re-usable without too much added attention.

Cheers,
Joe

I Did only apply varnish to one side but the next day i applied a sealer dad calls it dope to other other.

[Skew ChiDAMN!!]

The thing is, no normal finish is 100% waterproof.

At best they'll just slow down the water absorption rate, let's say a hundred-fold... but that just means it'll take 3 months to move as much as untreated wood would in one day. :shrug:

For something that'll be more or less permanently over water, you really need to take the movement into account.