533 Royal St. Renovation

Renovation Report: Repointing the Masonry of HNOC’s Historic Buildings

October 16, 2026

Curator Lydia Blackmore provides a behind-the-scenes dispatch from the renovation of our 533 Royal Street campus.

A woman in a hard hat and reflective vest smiles next to a historic brick wall that is being repointed.

HNOC Curator Lydia Blackmore receives training on repointing masonry. Photo by Keely Merritt, HNOC

By Lydia Blackmore, curator

In my annual review, I set a goal of learning the basics of masonry and repointing one brick in the 533 Royal Street site. I’m proud to say that I have achieved that goal! Mario Machnicki, president and founder of US Heritage Group, a company specializing in preservation masonry, led a two-day training for the masons working in our historic buildings on Royal and Toulouse Streets. 

Repointing masonry is the process of replacing the mortar in between bricks. Proper mortar not only holds bricks together, creating a strong wall, but also allows bricks to breathe. As low-fried ceramics (such as a terra-cotta flowerpot), bricks absorb and release moisture. This porousness enables our historic buildings to expand and contract in response to the environment, adding to their strength and adaptability over time. Mortar is a sandy mixture and should be softer than the bricks it surrounds, acting as veins for moisture to escape. This means that it will, and should, erode over time, making repointing necessary for building maintenance and preservation.

A mason repoints historic brickwork at HNOC‘s 533 Royal Street campus. Photo by Keely Merritt, HNOC

All the buildings on the 533 Royal Street site are made of bricks of varying ages and hardness, requiring expert knowledge of chemistry, materials, and craftsmanship from our masons. During their recent training, masonry contractors DeLeon and Sons learned how to properly mix hydraulic lime mortar, techniques for pushing mortar between bricks, and historic tricks and tools that keep old buildings standing for centuries. Using trowels, hawks, dowels, whisk brooms, and horsehair brushes, masons will touch nearly every brick on our original campus.

Don’t worry, no one will see my repointed section. It will be hidden behind a wall in the new public bathrooms.