How To Paint Shiplap Gaps. 1) to protect it from paint splatters and drips, cover the floor and surrounding area. 2) with sandpaper or a palm sander and wipe away any remaining sawdust, sand down the shiplap boards.
3) apply a primer product if it is separate before the paint and allow it to dry completely. About 2 hours in to this process, and seeing how time consuming it was, i wished i had bit the bullet and gotten a paint sprayer.
Agree with paintguy, roll and back brush. Also to know is, what color do you paint the wall behind shiplap?