- 1). Assess the problem and make sure all the bricks themselves are still solid. In extreme cases, moisture through mortar joints can cause brick faces to flake or peel. Identify all areas with damaged mortar, marking locations with tape if they are scattered across a wall. Test suspect joints by running a long, thin-bladed trowel against the mortar. If the joint is bad, the trowel will scrape off mortar and dust.
- 2). Clean all bad joints thoroughly. Scrape away any weak or powdery mortar with a wire brush and the thin trowel. Get to firm, solid mortar all around the bad spots. Dig out deep joints with the trowel, but don't go the full depth of the brick; there should be solid mortar at least halfway into the joint. Use a Shop-Vac to finish cleaning the joints, making sure to utilize blower mode to blow out all loose mortar and vacuum mode to pick up dust.
- 3). Replace individual damaged bricks by chipping out the mortar and the old brick. Work carefully and don't remove more than one brick at a time. If many bricks in an area are seriously damaged, call a professional, as removing them could weaken the wall and cause it to slump or fall down. Replace a single brick by first getting the entire old one out. Lay mortar on the bottom of the new brick, slide it into place, then mortar all around it with the thin trowel.
- 4). Mix the new mortar carefully. Match it to the existing mortar as best you can, noting that this can be difficult in very old buildings that may have used different sands and such ingredients as ground-up oyster shells or carbon black. Try to duplicate the texture of the replacement mortar -- the roughness due to its sand content -- to the original. Mix mortar slowly, with little water at first. Let it stand, then add water until the mortar is fluid and easily workable, but not so thin it will run or drip out of the joint.
- 5). Dampen the tuckpointing area with a garden hose sprayer for large areas or with a hand-held mister bottle for isolated joints along a wall. This will keep the dry brick from absorbing all the mortar moisture before it has a chance to bond. Use the thin trowel, which should be slightly thinner than the joint, to force new mortar between the bricks. Work slowly, pushing mortar in as far as it will go before adding more mortar until the joint is filled to the depth of the existing good mortar.
- 6). Work in small sections, mixing and using only about as much mortar as you can place in 30 minutes. Finish the tuckpointing by smoothing the new mortar with a finishing tool, a steel device which is pressed into the mortar to shape it. The ideal shape is concave, creating a sort of semi-circle which will let water drain out of the joint, but match the finish to the existing joints. Dampen the finishing tool if necessary to get a smooth face on the new mortar.
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