How to Clean Up Sloppy Mortar Joints

Q.  The basement of our home has rough block walls with some very sloppy mortar joints. I’d like to paint the wall, but how should I clean up the joints first?

A.  Most professionals would probably use a 2-pound masonry hammer and cold chisel to chip off any excess mortar protruding from the joints. Then wash and rinse the entire block wall to get the best surface adhesion from the masonry paint. Use a trowel to fill any shallow spots or holes with mortar. Once it has dried, use a stiff brush to apply a primer coat of masonry-surfacer paint to the patched areas of the wall. Finally, paint the wall using a roller with a long-napped sleeve to work the surfacer into the face of the block.