When inexperienced amateurs try to paint over burnt wood, bleed-through usually follows. If you apply paint directly over the top of wood blackened by fire, coverage will prove impossible. A primer base coat can permanently seal burnt wood; unfortunately, the wrong type of primer will prove ineffective. Learn the proper way to prepare burnt wood for a painted finish, or flaking and bleed-through may result.
Put on a dust mask. Remove flaking pieces of burnt wood by sanding with 80-grit sandpaper. Do not move the sander against the wood grain or severe damage may result.
Smooth the wood by sanding it with a finer 120-grit sandpaper.
Wipe the burnt wood with sticky tack cloths. Thoroughly remove all dust particles, or the stain-blocking shellac primer won't adhere.
Coat the blackened wood with a stain-blocking shellac primer, using either a roller or natural-bistled paintbrush. Let the burnt wood dry for two hours.
Add a second coat of shellac primer. Let the burnt wood dry for another two hours.
Wash your application tools with denatured alcohol.
Apply latex paint to the primed wood. Use a roller or nylon paintbrush.
Do not try to prime burnt wood using a latex or acrylic base coat, or bleed-through will result. Don't use an oil-based stain-blocking primer in place of a shellac one; latex paint won't bond to oil-based undercoats.