Painting a board

I have searched several sites and found several different build forums. Never just about painting. So I have done a lot of homework on painting boards, but it looks like most of it is old boards or after laminating.

My favorite thing I saw was the dish soap affect, and alcohol one. Has anyone tried the dish soap painting method just directly to foam before putting the laminated sheets down?
I think the soap does a very creative design, and just curious if it can be done or if having to spray off the soap right after with water ruins the board. I know it probably has to dry for days after to let the water get out.

Any thoughts? My first board I used house paint directly to the foam, didn't look bad but this time im using an air spray gun to try and paint and want to add some designs to it.

thanks!