Matching color for masonry grout repair

 Masonry grout repair is one of the most important parts of maintaining a building, particularly if that building is older. Tuckpointing, the process of cleaning out old mortar and replacing it with new, is something that needs to be done every few years to keep up structural integrity.

But will it look right?

Newer grout may have a different formulation, especially if the building is very old. The mortar that’s been there weathering for a while will of necessity look different than new mortar, too. If you’re worried about your building looking like a patchwork quilt, though, don’t be. Skilled masons are able to match colors between old and new masonry grout. Here’s how it works.

Replacing receding or cracked grout

The first thing is to ascertain whether the repair is needed. Grout wears away over time—where once it was flush with the brick or stone, it begins to wear in and create concave cavities. As water pushes in, sometimes cracks can develop. When the mortar wears away enough, it’s time for tuckpointing.

If this repair is done correctly it blends in, and no one can tell the difference. If done wrong, it actually highlights the repair, creating an ugly patch on the building.

Mortar formulations

Mortar (or grout) is all made from the same ingredients: cement, lime, and sand. There are several different formulations, though, all made for different applications. The difference is the ratio. Some have better tensile or compressive strength. Others bond better, apply easier or have greater flexibility.

The most common types of mortar are N, S, M and O. For the repair to work, the proper mortar must be used. In rare cases other types may be used (in particular K, which is often used for repairs to historic and vintage buildings).

The color match

Once the proper general mortar formulation is figured out, it’s time to start adjusting. Using sand, lime and Portland cement, a trial and error match can be figured out by adjusting proportions. Typically several different samples with different formulations will be mixed up, then a sample laid out on a piece of scrap to dry to check the color. Wet mortar is darker than the finished product.

Some grouts have colored dyes added, and if it’s not gray that dye will have to be incorporated in the mix too. Color matching takes time and patience as well as experience.

Matching the color of old grout to new may take time, but it’s worth it. With the correct formula, new repairs will blend with old mortar to make a beautiful color-matched wall. Hiring the right contractor to do the work matters—you have to find one that will take the time and effort to do it right. If you have mortar repair work that needs doing, reach out to JK Industries. We’ll make sure to get the job done the way it’s meant to be.