Repointing Brick

To repoint the deteriorating brick on a house in Evanston, Illinois, John Machnicki first has to remove the high-cement mortar used in a previous patching job.

He refills the joints with a customized mix that matches the original lime-sand formulation. "Believe it or not: There are still contractors who think the harder the mortar, the sturdier the wall," he says.

1/2-inch-wide mason's chisel and a 2-pound masonry hammer, John Machnicki chips out the old mortar in vertical joints to prepare for the new.

After cutting a joint to a depth of 1 inch, he moves in with a pneumatic chisel to square the sides of the joints and blow out loose particles. "New mortar won't stick to dust," he says.

Mortar is ready for repointing when it sticks to an upside-down trowel. To keep the mortar from drying out too quickly in the joint, he first wets the wall with a water sprayer.

To ensure the mortar is uniformly compact, he presses three or four thin layers into the joint with a tuck-pointing trowel. He lets each layer set for 10 minutes before adding the next.

Mortar that protrudes from a joint traps water, rather than draining it away. Once the mortar hardens, Mario Machnicki cuts off the excess with the edge of his pointing trowel.

As his final step, Mario Machnicki beats the joints with a stiff bristle brush so the new mortar will match the roughness of the old. "I don't want it to look new," he says.