Mortar color comes mostly from the sand, with the joint profile and tooling shaping how it reads. To match an existing wall, a mason matches the sand and the finish, builds a test panel about 3 feet by 3 feet, and you judge it dry against the wall. Never let color decide the mortar type: the new mortar still has to be softer and more permeable than the brick. A mismatch you can see is a cosmetic problem. The wrong mortar is a structural one.
If you are picking brick mortar colors from a chart, stop. A chart cannot match your wall, because your wall has decades of weather, dirt and previous repairs in it. Matching mortar color is done with sand, finish and a test panel, and it is always second to using the right mortar.
What actually controls mortar color?
Most of it is the sand. The National Park Service says that the color and look of mortar are driven mostly by the sand, because sand is the largest ingredient by volume, and that a match should consider sand color, gradation and texture, plus the tooling and joint profile (NPS Preservation Brief 2).
So the factors are:
| What changes the look | What to ask about it |
|---|---|
| Sand color and grain size | Is the sand being matched to the original mortar? |
| Tooling and joint profile | Will the finish match the existing joints (flat, concave, raked)? |
| Cement and lime in the mix | Does the mix still fit the brick? (See below.) |
| Age and dirt on the old joints | Are we matching what the old mortar looked like when new, or what it looks like now? |
The last row is the one owners forget. Old joints carry decades of weathering. Fresh mortar will not look like them on day one, and a good mason will tell you that up front.
Why is the test panel the whole game?
The NPS describes a test panel, about 3 feet by 3 feet for brick, as the way to establish the standard of work before the wall is repointed (NPS). It lets you see the sand, the tooling and the color on your actual brick.
How to judge it:
- Wait until it is dry and cured. Do not judge color from wet mortar in the bucket or fresh in the joint. We do not have a source to quote on how much a given mix shifts as it dries, and that uncertainty is the reason to wait and look at the dried panel.
- Look at it in daylight, from the sidewalk. Not from two feet away on the scaffold. The wall is read from where people see it.
- Compare it to the part of the wall you want to match. There may be several shades of mortar already in the wall. Decide which one the panel should match, and say so.
- Take a photo, and write down what you approved. If the finished wall differs from the panel, you have a standard to point to.
What if the wall already has patches in different colors?
This is common on older buildings. Different repairs over the years leave different mortar in the same wall. A new repointing job can match one of them. It cannot make all of them look the same without redoing the whole wall.
That is a real argument for doing a full elevation instead of another patch. For when partial work makes sense, see tuckpoint the front or the whole building. Mismatched patches also show up in our list of tuckpointing mistakes that cost owners twice.
Can you pick any color you want?
You can ask. But color has to come after the mortar type, not before it.
The National Park Service says repointing mortar must be softer and more vapor-permeable than the brick, and no harder than the original mortar (NPS). It calls the assumption that harder or stronger is better a common error, and warns that stronger mortar damages the brick (NPS). The ASTM mortar types run from Type M (about 2,500 psi) down to Type K (about 75 psi), and more lime makes mortar softer and more permeable (NPS). For historic masonry, the NPS points to lime-rich mixes (NPS).
That means the right way to match color is to start with the correct soft mortar, then work the sand and finish until the color reads right. The wrong way is to pick a color, find the mix that makes it, and discover later that the mix is too hard for the brick. We explain the damage in the mortar mistake that ruins Chicago brick and compare mortar types in Type N vs Type S.
If you want a contrasting look, such as darker joints for a different appearance, that is a design choice to settle with your mason. On a landmark or inside a landmark district, ask the City what review applies first.
White powder on new mortar or brick is usually efflorescence, a salt deposit left when water moves through the wall. The Brick Industry Association says "new building bloom" on brickwork under a year old usually fades, while bloom that appears after a year usually points to excess water penetration or poor drainage (BIA). Do not judge your color match while a haze is on the wall.
How does curing affect the final look?
Lime-rich mortar needs protection while it sets. The NPS says high-lime mortars left to dry too fast can chalk and lose adhesion and durability, and advises light misting once the joints are thumbprint-hard and tooled, plus covering the wall for the first days (NPS). A joint that chalks is a durability problem, not just a color problem. Ask how the crew will cure the work, and do not accept a rushed schedule that skips it.
The NPS also notes that lime mortar continues to carbonate and gain strength for years. We do not have a source for how that changes color over time, so we will not promise one.
What should you ask before the crew starts?
- Will you match the sand and the joint finish to the existing mortar?
- Can I see a test panel, dry, on my wall, before you do the elevation?
- Which part of the wall are you matching, since there are several shades?
- What mortar type is this, and is it softer than my brick?
- How will you protect and cure the joints?
Our tuckpointing crew builds the panel first. The Chicago tuckpointing guide explains where color fits in the rest of the job.
Common questions
Mostly the sand, according to the National Park Service, along with the tooling and joint profile. Sand is the largest ingredient by volume, so matching its color, grain size and texture is how a mason matches the existing mortar.
Wet mortar often looks different from cured mortar, but we do not have a source for how much a given mix shifts. That is why you should judge color only on a dry, cured test panel and not from fresh mortar in the joint.
It can come close, but old joints carry decades of weathering, so fresh mortar will look different at first. A test panel judged dry, in daylight, from where people see the wall gets you the closest match.
A chart can show general shades, but it cannot match your wall. The match depends on the sand, the finish and the age of your existing joints, so ask for a test panel on your own wall.
Sources
- National Park Service: Preservation Brief 2: Repointing Mortar Joints in Historic Masonry Buildings (PDF)
- Brick Industry Association: Technical Note 23A: Efflorescence, Causes and Mechanisms (PDF)
Facts last checked: October 7, 2026.
This article explains general rules and common situations in Chicago. It is not legal advice, and City rules change. For a specific property, check with the Chicago Department of Buildings or a licensed professional.