How to Paint a Cinder Block With Drylok

The pores in cinder blocks make them especially susceptible to moisture.

Applying paint to cinder blocks will not waterproof them. Instead, paint cinder blocks with DRYLOK, manufactured by United Gilsonite Laboratories in Scranton, Pennsylvania, to seal the blocks and create a waterproof barrier that can protect your home.

1. Clean the cinder blocks with mineral spirits or a similar solvent to remove dirt, dust, grease, oil or wax from the surface. If the cinder blocks were previously painted, strip away all old paint with paint thinner or paint stripper.

2. Rinse the entire cinder block surface with clean water to remove residual cleaner. Inspect the surface. Patch any cracks or holes in the cinder block with fast-setting cement patches, applied per product instructions. Allow the wall to dry completely before continuing.

3. Stir the DRYLOK thoroughly with a paint stirrer. Do not add paint thinner or additives.

4. Paint DRYLOK onto the surface with a nylon bristle paintbrush. Apply an even coat, being sure to work the DRYLOK into the pores of the blocks. Allow the first coat to dry for three hours before continuing.

5. Apply a second coat of DRYLOK to the surface. Allow the second coat to set for three hours, and then inspect the surface. Patch any holes or gaps in the paint with a third coat as necessary. Allow the DRYLOK to set overnight before touching the cinder blocks.

Tip

If your cinder blocks have begun to form efflorescence, a powdery white material that often appears on moist masonry, you must remove it before applying the DRYLOK. Use a specialized masonry cleaner or a diluted solution of muriatic acid. Make sure you rinse the surface thoroughly after cleaning to avoid contaminating the DRYLOK. The surface of the cinder block, as well as the air around the cinder block, must be at last 50 degrees Fahrenheit for the DRYLOK to bond properly. If you want to tint the DRYLOK to achieve a different color, use alkali-proof paint tint, diluted by half of the recommended application for regular paint.

Warning

Old paint applied before the 1980s may contain lead. Removing this paint will create a serious health hazard in your home. If you are unsure about the type of paint you need to remove from the cinder blocks, contact a professional painter or builder for help.