Replies

1. 
   HowardAcheson | Jul 18, 2004 07:13pm | #1

   There is no way to totally seal wood short of encasing it in paraffin or 1/4" or more of pour on epoxy.

   So, moisture will always get through the finish. If the wood is flatsawn from an area near the center of the tree, there will be a tendency to warp with changes in long term relative humidity. Not much you can do about it except to mount the panel in a way that supports the panel across the grain. But, you must allow for the expansion and contraction from season to season.

   Howie.........
1. 
   Jellyrug | Jul 18, 2004 10:50pm | #2

   Spiff,

   It's always a good idea on a solid wood top, to finish in a manner which allows equal moisture permeation, both on the top and bottom. This means using the same kind of finish and number of coats on both top and bottom.

   How did you fix the top to the frame?

   I use a specific method, which allows expansion and contraction, to avoid checking, but it will not allow cupping.

   Willie

   Edited 7/18/2004 3:51 pm ET by Jellyrug

1. 
   GT | Jul 19, 2004 12:29am | #3

   I used blocks glued to the frame and drilled elongated holes to allow for cross grain movement.Wounder if a solid cleat screwed to the underside would help,or just re do it with klin dried lumber..thanks

1. 
   Jellyrug | Jul 19, 2004 03:55am | #4

   Spiff,

   Suggest you try and straighten the top by re-sanding and removing the finish, then placing it on the floor, supported by two 2x4 studs, flipped as shown in the photo. try and induce humidity under the top, by either having water in a shallow tray between the 2 x 4's, or using wet rags. with some luck, it my pull back and you can re-finish.

   Best way to fix the top to your frame, is using corner braces, cut 45 degrees at the ends, glued and screwed to the frame brace at each corner.  Each corner brace, should have a slot milled into it, either with a router, or a dado. You then cut a block with a tenon, which fits into the slot and screw the top to this block, with a little clearance between the cross brace and the shoulder of the tenon. This way you pull the corners of the top down and you allow for wood expansion.

   Don't know if this was a good explanation, but can post a picture if you want.

   Willie

1. 
   joinerswork | Jul 19, 2004 04:34am | #5

   Jelly,

   I think you meant to suggest drying out the underside of the top, since it is the side that apparently took moisture.  Adding moisture would add to the cup, as the underside gets wider than the top side.

   Cheers,

   Ray

2. 
   Jellyrug | Jul 19, 2004 06:20am | #6

   Yep,

   Flip the top in it's current position, so the underside (current position) dries and the other side is exposed to a bit of humididty.

   Guess I'll fail miserably as a technical writer.

3. 
   joinerswork | Jul 19, 2004 03:29pm | #8

   Jelly,

   Gotcha, it's all in how you look at it, and that's hard to do here sometimes, with no pictures to look at!!

   Regards,

   Ray

4. 
   GT | Jul 19, 2004 01:34pm | #7

   That would be great,please send photo..

5. 
   Jellyrug | Jul 20, 2004 04:56am | #11

   Spiff, this is how I do it.

   Willie

   
2. 
   whoover | Jul 19, 2004 08:51pm | #9

   I am assuming that the source of your problem is that you did not finish the bottom of the table top with as much finish as you put on the top.  Hence, moisture entered the table top from the bottom and caused the cupping. 

   The object should be to remove the moisture from the underside and then seal that surface as well as you have sealed the top side.  To get the moisture out, use the grass trick.  Put the table top with the bottom side up out on your lawn on a sunny day.  The sun will dry the bottom surfacer (the one now facing the sun) and the grass will tend to moisten the top surface.

   Once the surface is flat, apply as many coats of finish to the bottom surface as the top surface. 

   My guess is that there will be no need to cut, saw or sand.  Just dry the bottom surface and seal it.

   Bill

1. 
   GT | Jul 20, 2004 01:18am | #10

   Sounds ok,will give it a try..thanks

3. 
   Patto | Jul 21, 2004 06:33am | #12

   HI,

   If you do decide to replace the top (I would be tempted), it looks from the photo that you might have placed all of the boards pith side up, whih give a continuous curve in one direction. A strategy to avoid such a huge curve is to alternate flat sawn boards so that they are bar up, pith up, bark up etc. The individual boards still cup just as much, but the total effect translates to a set of waves across the width. Yuo are less likely to crack the top from stress once held down with buttons (my preference becaust it is easy) or however you secure it.