Removing Paint and Repointing Brick: Restoring Historic Masonry the Right Way

Few features define a historic building like its original brickwork. Whether it's a century-old chimney, a stately foundation, or a beautifully detailed façade, historic masonry was designed to last for generations. Unfortunately, years of paint, hard cement repairs, and deferred maintenance can conceal its character and compromise its performance.

A thoughtful restoration begins by understanding that old brick is different from modern masonry. Historic bricks were typically softer and more porous, and they relied on equally soft, lime-based mortar to absorb movement and moisture. Preserving those materials requires patience, the right techniques, and a commitment to doing the work carefully.

Removing Paint Without Damaging Brick

Paint can trap moisture within masonry, leading to spalling, deterioration, and premature mortar failure. While removing paint often reveals the original beauty of historic brick, the process should always be approached conservatively.

Before beginning, determine whether the paint is lead-based, especially in buildings built before 1978. If lead is present, follow all applicable safety requirements and containment procedures.

Whenever possible, start with the least aggressive removal method. Chemical paint removers formulated for masonry can soften multiple layers without damaging the brick surface when used according to the manufacturer's instructions. Gentle scraping and low-pressure rinsing often complete the process.

Avoid abrasive blasting methods such as sandblasting, which permanently erode the protective fired surface of historic brick. Once that surface is removed, the brick becomes more vulnerable to water infiltration and weathering. The goal isn't simply to strip away paint—it's to preserve the integrity of the masonry beneath it.

Evaluating the Mortar

With the brick exposed, inspect the mortar joints carefully. Missing mortar, deep cracks, loose joints, or previous repairs made with hard Portland cement are common signs that repointing is needed. Keep in mind that weathered mortar is designed to be the sacrificial element of the wall. It should wear before the brick does. When the mortar has reached the end of its service life, replacing it helps protect the surrounding masonry.

Prior to the1880s pure lime mortars composed of non-hydraulic lime putty and local sand (typically 1 part lime to 3 parts sand) was used.  These mortars were extremely soft, highly vapor-permeable, and completely flexible.  Any restoration work on buildings from this era should use Type K mortar (approx. 75 PSI) or pure lime mix for matching.

From the 1880s through the 1910s “transition” or natural hydraulic cement mixes were used.  During this time period natural cements or small amounts of early Portland cement were mixed into lime-heavy batches to accelerate up setting times.  Retained high lime content for flexibility and breathability.

From the 1910s and through the 1920s early Portland-lime blends were used that resemble modern Type O mortar (approximately 350 PSI and comprised of 1 part Portland cement, 2 parts lime, 9 parts sand).  These were harder than 19th-century mixes, but still significantly softer and more flexible than modern structural brick mortar.

Removing Deteriorated Mortar

Old mortar should be removed carefully using hand tools or specialized masonry tools that minimize the risk of damaging adjacent brick. The objective is to remove deteriorated material while preserving crisp brick edges. Clean the joints thoroughly before installing new mortar. Dust and loose debris prevent proper bonding and shorten the life of the repair.

Matching the Original Mortar

One of the most important aspects of historic repointing is selecting mortar that matches the original in strength, composition, color, texture, and joint profile. Using mortar that is harder than the historic brick can create problems over time. Instead of allowing the mortar to absorb normal movement, excessive hardness transfers stress to the brick itself, increasing the risk of cracking and surface failure.

Whenever practical, analyze the existing mortar before mixing a replacement. Matching the original materials helps ensure the repaired wall performs as intended.

In general, the following mortars should be used for each era:

Pre-1880's: Type K mortar (approx. 75 PSI) or pure lime mix mortar

1880s-1920s: depending on the hardness of your historic masonry, weather

exposure, and setting time use Pozzolanic Hydraulic Lime mortars (PHL 2.0,

PHL 3.5, or PHL 5.0), Natural Hydraulic Lime mortars (NHL 2.0, NHL 3.5, or

NHL 5.0), or Non-Hydraulic Lime Putty (CL 90-S)

1920s-1950s:  Type O mortar

Post 1950s: Type N mortar

New Brick Construction: Type S mortar

As a rule, one should never use Type N or Type S modern commercial mortars on pre-1920 soft clay brick, as they will cause irreversible cracking and spalling.

Installing New Mortar

Proper repointing is done in thin lifts, allowing each application to firm up before adding the next where necessary. Lightly dampening the brick beforehand helps prevent excessive moisture loss from the fresh mortar, promoting a stronger cure. After placement, tool the joints to match the original profile. The finished joint should blend naturally with the historic masonry rather than draw attention to the repair.

Protect newly pointed areas from direct sun, wind, freezing temperatures, and rapid drying until the mortar has cured properly.

The Value of Patience

Historic masonry restoration rewards careful workmanship more than speed. Every brick preserved, every mortar joint properly restored, and every inappropriate repair corrected helps extend the life of the building for decades.

Removing paint and repointing brick isn't simply maintenance—it's stewardship. By respecting traditional materials and proven techniques, homeowners and preservation professionals preserve not only the appearance of a historic structure but also the craftsmanship and history embedded within every wall.

When restoration is done thoughtfully, the finished project doesn't look new. It looks authentic—and that's exactly the goal.