How to Use Mortar Caulk
Mortar caulk is especially formulated for use with outside mortar. It works on cinder block, brick, stone concrete and many other forms of masonry. Mortar caulk is specifically designed to fill small holes and cracks in mortar and really only suitable for holes less than about 3/8-inch thick or deep.
Step 1 – Preparation
Remove all the loose brick or concrete from hole or crack to make sure you get a strong bond to the hole. Make sure there are no signs of grit or dirt. Clean around the area with a solid bristle brush to clear the location of anything that can interfere with the performance of the mortar caulk.
Step 2 – Caulking
Use the caulking gun and squeeze the caulk into the crack or hole. Be liberal, but do not over fill the hole. If it starts to puff out of the hole, smooth out the excess and remove what you don’t need. Leave it to thoroughly harden and set. Sand it down if needed and apply a little more if the caulk sinks in too far. It shouldn’t shrink but it could sink in further than you first expected it might.