Boulder's older neighborhoods contain a significant amount of historic brick and stone construction, some of it dating back to the 1870s, and restoring or repairing this older masonry requires a different approach than working on new construction. Historic mortar mixes were often softer than modern Portland cement mortars, and repointing historic brick with a mortar that's too hard can actually accelerate deterioration of the brick itself, since the harder mortar forces the brick to absorb the stress of expansion and contraction that the mortar joint is supposed to handle. Getting this wrong is one of the more common and costly mistakes made on historic masonry restoration, and it's not always obvious until years later when the brick itself starts to spall. Boulder Masonry Pros approaches historic masonry work with attention to matching original mortar composition and installation techniques, rather than defaulting to modern standard mixes on buildings where that approach causes long-term harm. Homeowners with older Boulder properties benefit from a contractor who understands this distinction before any repointing work begins.