If you can paint a wall, then you can seal concrete block. In order to seal a concrete block wall, you need to find a high quality sealing product and then apply it in at least two coats to your concrete block wall. Sealing your concrete block wall will help to keep moisture out of your basement or whatever structure is made from the block, and it will also help to keep the room inside comfortable. Concrete block that makes up the foundation of your home is an extremely important part of your investment. Make sure you protect the investment in your home by sealing your concrete block.