Adapt repointing methods for stone masonry (limestone, sandstone) versus brick, accounting for stone's different absorbency and joint characteristics

Steps

1. Recognize that NPS Preservation Brief 2's general repointing principles apply to stone as well as brick, but stone introduces material-specific considerations, particularly high absorbency in some sandstones and limestones
2. For highly absorbent stone (per Brief 2's guidance), pre-wet the wall with a continual mist for a few hours before repointing so the stone doesn't pull moisture out of the fresh mortar too quickly and cause weak, powdery joints
3. Assess whether the stone is a soft, friable type (some sandstones/limestones) requiring an even softer, more permeable mortar than would be used for brick, to avoid the same hard-mortar-causes-spalling mechanism seen in brick walls
4. Account for irregular stone joint widths and rubble/ashlar coursing patterns, which often require more mortar-tooling judgment than the more uniform joint spacing typical of brickwork
5. Match mortar color carefully against stone, since stone walls often have more visually prominent, wider joints where mortar color mismatch is more noticeable than on brick
6. Where the stone itself shows deterioration (delamination, sugaring, spalling) rather than just joint failure, treat that as a separate stone-conservation issue requiring specialized stone consolidation/repair expertise beyond standard repointing