How to clean or encapsulate mold on drywall without removing drywall

Mold encapsulation is used for materials that are contaminated but cannot be easily removed. Example is floor joists, roof rafters, etc. These materials are cleaned to remove as much mold as possible then are painted with the encapsulation product. They must be completely sealed or mold growth will come back. Drywall, paneling, insulation are easily removed and replaced. I would not attempt to seal drywall as mold growth usually starts from inside out. The surface mold is a sign there is a bigger mold problem behind the drywall.

Just a question at this point: Do you know the source of the moisture and is it from behind the wall?

Surface mold does not always start from behind the drywall...sometimes it is just 'surface' mold. Use two parts water and one part chlorox and wipe it clean. This will clean it and then paint with Kilz.

If you do encapsulate it, it will eat through the drywall.

This is only good for a small area. Large areas are best treated by removing the drywall and if the mold is dry, dampen it first before removing drywall. This will keep the mold on the drywall and not floating through the air. Good luck!

fix the problem then seal with shellac. Shellac is clear and seals all stains. Or you can use kilz sealer. or zyzzic [sp] sealer primer but they are white.