Sealing plywood w/BLO to prevent warping
I have some 3/8" thick engineered click-lock maple flooring I would like to put onto two 4'x8' sheets of 3/4" plywood to make a chair mat in my basement. It would be going over berber carpet with a concrete subfloor.
I'm concerned that moisture coming up from the concrete could cause the plywood to warp. The guy in lumber at Home Depot thought that sealing the bottom side of the plywood with Boiled Linseed Oil might prevent this.
1.) Would BLO work for this?
2.) Are there better alternatives?
3.) Should I be concerned with warping to begin with? I install floors for a living but plywood warping isn't something I ever think about since its always nailed down.