ESRepointing fails for two reasons: the new mortar does not bond, or the brick face gets chewed up during removal. Both come down to how the joint was opened. A tuck pointing blade is a narrow, controlled cut — closer to surgery than to demolition.
The geometry of a repointing cut
Tuck pointing removes deteriorated mortar from a masonry joint to a consistent depth, leaving square shoulders on both sides so new mortar can key in mechanically. The tools are either a single narrow blade run twice, or a paired-blade arbor that cuts both sides of the joint in one pass.
Joint widths on brick and block commonly sit between 6 mm and 12 mm. The blade or blade stack has to match that width within a millimeter or two. Too narrow and you leave old mortar on the shoulders; too wide and you cut into the brick arris, which is the single most common way repointing turns into a tuckpointing-and-replacement job.
Depth: enough for a mechanical key, not more
General masonry practice calls for removing mortar to roughly twice the joint width, so a 10 mm joint is raked to about 20 mm. That depth gives the new mortar enough surface to bond and enough body to resist differential movement.
Going deeper than the design calls for weakens the wall section and is slow work with hand tools, which is where operators start pushing the saw. Going shallower leaves a thin skin of new mortar over old material, and that skin fails within a heating cycle or two.
A depth stop on the guide, or a reference line scored at the target depth, keeps this consistent across a long elevation.
Bond selection for mortar
Mortar is soft and highly abrasive. It wears a diamond segment's matrix quickly, so a hard bond usually lasts longer in continuous repointing than a bond tuned for harder masonry units.
The trade-off is that a hard bond cuts slower and generates more heat, which matters on sandstone and on soft historic brick. On those substrates, a slightly softer bond with a lighter pass is easier on the masonry face, even if the blade itself wears faster.
Twin-blade setups versus single blade
A twin-blade arbor is faster and produces a more uniform joint, because both shoulders are cut at the same depth in one pass. It also removes the temptation to widen the joint on a second pass to correct a wandering first cut.
Single narrow blades are more forgiving on irregular historic joints, where widths vary from brick to brick along the same wall. On that kind of work, a single blade and two careful passes usually damages less masonry than a fixed stack that is slightly too wide for half the joints.
Dust is the real hazard
Cutting mortar releases silica from both the mortar and the masonry unit. On a scaffold, the dust is at face level and stays there. A shroud connected to a suitable extractor, plus a respirator rated for the exposure, is the minimum.
Eye protection needs to be sealed goggles rather than open safety glasses, because fines come off the joint line at eye height. Hearing protection matters on long elevations, and gloves should be cut-resistant rather than thin nitrile.
What goes wrong on site
- Blade too wide. The arris chips, and the repair now includes brick replacement.
- Cutting dry with no extraction. Visibility drops, the operator leans in, and control goes with it.
- Raking to inconsistent depth. New mortar sits proud in places and recessed in others.
- Not cleaning the joint. Dust and loose mortar left in the groove become a bond breaker.
- Cutting when the wall is saturated. Wet masonry smears instead of cutting cleanly.
Matching the blade to the wall
Start from the diamond saw blade range and filter by kerf width first, then bond. For general brick and block repointing, a segmented diamond blade covers the work; where the joint needs a cleaner shoulder and the masonry is softer, a hot-pressed turbo mesh blade leaves a tidier edge.
Two background pieces are useful: dust control when cutting and grinding masonry, and the angle grinder safety checklist for guard, RPM, and PPE requirements.
Before the first cut
Confirm the joint width on a sample of ten bricks rather than one, check the blade's RPM rating against the tool, and test the depth stop on a small area out of sight. If the mortar is harder than the brick — common on hard-burnt units repointed with cement-rich mortar — slow the feed and accept a narrower blade rather than forcing a wider one through.
Send us the joint width, masonry type, and required depth and we will confirm the blade stack specification that fits.
