Things required for a shiplap painting project: Drop cloth, House Paint, Sandpaper and good-quality Paint Brush (palm sander), paint roller, and tray Spackle Paintable caulk.
1- First of all cover the entire floor and surrounding area to protect it from paint splatters or drips.
2- After floor covering is done, sand down the shiplap boards with sandpaper or with a palm sander and remove any remaining sawdust.
3- If you are looking to use a separate primer product, apply it just before the paint and allow it to dry totally.
4- Now try to apply the first coat of paint with a help of paint brush/roller prior to placing the boards on the wall if possible. If you are thinking about how to paint shiplap grooves, you will discover that using a small paintbrush makes it much simpler to reach in all of those nooks and crannies which at first sight are looking tough to reach.
5- If you have already installed the shiplap that’s good.If not, no problem just go for it, after installing clean the nail holes and fill it with a paintable caulk.
6- Once the caulk is dry completely, sand the surface gently.
7- Now we can go for the final coat of paint, try to use a small paintbrush to ensure the nail holes and grooves are totally covered.