Cupped piece of wood needs to be flattened

[CHARLIE]

A friend brought be a 5/16 inch thick, 18 inch diameter wood disk that had cupped.  It is painted black and I suspect it was sitting next to a window.

Does anyone have any ideas how I can get that disk flat again?  I have thought of putting it in a box with high humidity (wet towels) and a weight on top, but not sure that will do it.

If I can get it flat, I plan to remove the black paint from the bottom and glue on a 1/4 inch piece of wood with the grain running 180 degrees to the grain of the original disk. Other than that, does anyone have any ideas on how to keep it from cupping again once I get it flat?

[Don_Papenburg]

Wet the concave side .
the convex side has more moisture making it expand . you might be able to just dry the convex side. as far as keeping it flat ???????????I was always told to keep both outsides the same thickness of the same or similar woods.

[jueston]

it sounds like the paint is on the concave side, which makes sense. the unpainted side gains moisture faster than the painted side, so it bowed out to the unpainted side. what you need to do is balance out the moisture, instead of trying to make the painted side gain moisture, i would try to get the whole thing down to as low a moisture as possible, and then put an even coating of whatever you use(poly?) on both sides, and that should avoid one side gaining moisture faster.....

if you laminate another piece of wood onto the bottom you are basically creating a tug of war, and in the end my guess is one of pieces will just crack down the middle....

[Busy Beaver Lumber]

I could come sit on it for a spell :D 300 lbs can be very persuasive 

[LeeB]

I could come sit on it for a spell :D 300 lbs can be very persuasive 

Then it would have a big crack in it.  :D

[Chuck White]

I could come sit on it for a spell :D 300 lbs can be very persuasive 

Then it would have a big crack in it.  :D

Or on it!  ;D

Sorry Lee, I couldn't resist!  :D

[LeeB]

Depends if the cup is up or down.  :D  No need to apologise to me. I just hope BBL doesn't mind us poking fun at him. If it helps him feel any better, I know all about that 300 lbs.

[CHARLIE]

Thank y'all for the information. I have a better understanding of the situation now.  I guess I didn't describe the piece of wood very well 'cause it is painted all over, top and bottom.  I was considering removing the paint on the bottom.     Now I know I need to remove moisture from the top and I'll give that a go. Thanks!

[Busy Beaver Lumber]

Chuck. Lee, or anyone else.

Anyone that knows me can tell you i have a good sense of humor and  can take a joke as quick as I can tell one. In fact I love to laugh and kid around. One of the younger lads that I work will is always kidding me about my weight. He says I am what happens to people when their metabolism slows down.

Have all the fun you want, this is one Beaver you can not offend with good hearted humor.

[Magicman]

I have never dealt with painted boards, but with unpainted ones, I lay them in the sun with the cup down.  Keep a watch on it, and when it levels out move it to the shade to relax.