wrote:

I bought a wooden countertop at a high-end cabinet shop's yearly yard
sale last summer. It's 90"L x 25"W x 1.5" thick. I brought it
home on
the top of my jeep, and it cupped. Good side up, the cup is center up
along the length about 3/8 inch, over 1/3 of the length from the left
edge. It did not settle over the past year.

The edges are doubled 3/4 inch boards, and the field is 3/4 inch also.

I'm condsidering kerfing the underside to flatten to the top. My
start
would be 3/4 or maybe 7/8 inch deep kerfs thru the doubled boards
on the
affected end, probably at 1/2 inch spacing.

snip

Have you tried to clamp this top to flatten it?

If you have some pipe clamps, cut a 2x6x10ft construction timber into
4-30" lengths and clamp them equally spaced, to the top for a couple
of weeks.

Build the frame of your bench, then mount top to it.

My guess is it will stay flat.

Kerfing would be my last choice.

Have fun.

Lew

in addition to Lews idea, if it s bare wood you could also wet the cup
side to expand the wood.
ross
www.highislandexport.com
www.sandlakeoutpost.com