How to Cover a Painted Cinder Block Fireplace

Remove the paint from the cinder blocks with a sandblaster or grinding tool.

Scrub the cinder blocks with a solution of three parts water to one part bleach. Allow the cinder blocks to dry.

Prepare a batch of mortar that contains one part Portland cement and two parts washed sand until it is as thick as mashed potatoes. Mix the mortar for at least 5 minutes.

Apply water to the surface of the cinder blocks to dampen it. This prevents the mortar from cracking as it sets by stopping the cinder blocks from drawing moisture away from the mortar.

Dampen the back of the first veneer stone with the masonry brush.

Add 1/2 inch of mortar to the back of the stone and the cinder blocks where it's being installed.

Place the stone into position on the fireplace. Rotate the stone slightly as you set it on the cinder blocks.

Continue installing the stones onto the cinder blocks using this technique. Wipe away any mortar that seeps up between stones as you set them because it's harder to clean the mortar after it sets.

Place mortar into the gaps between the stones with a grout bag.

Slide a joint tool over the mortar between the stones to smooth it. Allow the mortar to set for the time specified by the manufacturer.

Apply concrete sealer to the stones, following the instructions provided by the manufacturer.