Bad things may happen to great drywall. Especially when upgrading walls by removing old wallpaper or paneling, drywall surface paper might be ripped or remove pieces using all the old wall finishes. The surface paper is a vital part of drywall, protecting the gypsum from moisture. As you don’t have to replace the drywall, you do have to seal it as part of the process of texturing over drywall with damaged paper.
Cut away the ragged edges of any torn or missing drywall surface paper using a razor knife. Cut the rest paper into right sides, creating a square or rectangular-shaped section.
Seal the missing-paper places with an oil-based sealer or shellac. Apply the sealer over the trimmed edges, sealing existing paper borders adjoining the torn place. Allow to dry completely.
Skim-coat the affected region with joint compound and a trowel. Spread the compound thinly (no longer than 1/32 inch). Apply a second coat as required to make the missing-paper area mix with the surrounding drywall material. Allow to dry completely.
Sand smooth. Wipe wall down with a dry rag or towel to remove all dust.
Apply affected region using a primer sealer paint. Allow to dry thoroughly.
Spray texture above the affected drywall places, feathering the texture into surrounding areas by spraying brief, light strokes.