How to Match Mortar | Ask This Old House

Ask This Old House mason Mark McCullough explains how to match mortar for repointing jobs.

Time: 1 hour
Cost: $50

Skill Level: Moderate

Tools List for Matching Mortar:
Buckets
Trowel

Shopping List:
Lime
Sand
Portland cement
Scrap wood

Steps:
1. If the mortar is not gray, then a dye was used. Take a small sample of the mortar, bring it to the nearest brickyard, and ask them to match the color for you.
2. If the mortar is gray, you might be able to get a close match with the premixed bags of mortar. The following steps are how to attempt an exact color match.
3. Take a couple small buckets and add proportions of lime and Portland cement. Keep close track of how much of each you put in each bucket. Adding more lime will make the mortar lighter and adding more Portland cement will make it darker.
4. Take two larger buckets with equal proportions of sand in them. Add the smaller buckets with the different lime/Portland cement mixtures to the buckets of sand and mix them with the trowel.
5. Add a little bit of water to each bucket and mix up the mortar. Add more water as necessary until the mortar is roughly an oatmeal texture.
6. Scoop out a small amount of each mixture onto the scrap wood with the trowel and very carefully peel back the blob so only a thin layer is on the wood. This will allow the mortar to dry faster.
7. Allow the mortar to dry and compare it to the joints requiring repointing. Keeping in mind that the mortar will continue to get lighter as it dries, pick the mixture that matches the mortar best. Use the same proportions as the ones you originally wrote down to mix a larger batch of mortar and begin repointing.

Resources:
Matching mortar can be a trial-and-error job. Keep track of the quantities of lime, sand, and Portland cement used in each test sample and let each sample dry before matching it to the mortar being repointed.

If the mortar is not gray, then it has a dye added to it. Locate the nearest brickyard and ask someone there to help match the color.

Most of the materials required for matching and making mortar and also for repointing can be found at home centers and brickyards.

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How to Match Mortar | Ask This Old House

[BradlyFackrell]

Third generation mason here: I commented on your Facebook page yesterday and then this episode came on Pluto TV…what timing! I just want to say that this is not as easy as Mark makes it look. As I’ve said, Mark is a great mason but I’m thinking that his four-minute segment just wasn’t enough to “go into the weeds”. My customers see things like this clip and give me grief because I can’t make the mortar match…perfectly. Keep in mind that Mark did not show the final CURED mortar NEXT to the old existing mortar. Matching is a long process that is based on four main factors 1) mortar color (added pigment), 2) lime and cement color and ratio, 3) sand color, texture and grain as well as ratio to lime and cement and 4) weathering. Also, as you walk around a building, the colors will vary so now matching is multiplied by the number of different shades around the building. As Mark pointed out, a mortar sample can be broken down to help determine these things but there is still a lot of trial and error to get to a point where the new mortar does not stand out. A good mason will always make an attempt and get as close as possible, but the process involved in getting a "close match" can take days and is not economical on small projects. “Mortar matching” makes sense on large restoration projects but you will still see the difference if you look closely.

[thefowlyetti]

No need to mention the color of sand that you use, that is only the major determining factor in what the color of mortar is. Great job guys.

[brentdreisbach]

I have had success buying pre-mixed mortar, usually too dark gray, then adding a small amount of white sanded grout.

[emtffzartman]

I think it seems more like trowel and error...

[Nashr]

Please share more information about the various strengths of different mortar mixes and their compatibility with old buildings. Color really is not the primary concern. What would be most helpful is to know what was used on the typical bungalow 100 years ago. By that I mean the ratio of Portland to lime. Sand is easier to figure out since it’s usually whatever river sand was available locally at the time. Usually it’s a finer graded sand than is common today since the mortar joints were smaller. Thank you for the information though!

[bobbysilver]

This is VERY incomplete. The colour of your sand is the biggest single factor. This can differ dramatically depending upon where you are located in the country (different quarries have different colours of sand).

[ConstructionMachineryChannel]

Another good video, learned about how the color changes when it has more portland or lime.

[jenniegem]

One bad thing about using portland to make the mortar darker is that is makes it stronger. You don't want the mortar to be stronger than the brick itself. You want the mortar to crack before the brick does.

[Flat]

Excellent tutorial. I’m heading down to my local brick 🧱 supplier and getting a pre mixed bag of colored mortar . Thank you

[moonblink]

when you buy the additive dye, a little goes a LONG WAY. So don't add very much at all. I didn't see this "pre-mixed" stuff at the store, but that's cool if it exists.

[saulgoodman]

Mark's cement looks like something after I do after I have my morning coffee.

[akbaxb]

Thanks for raising the awareness on this topic.

[RegulareoldNorseBoy]

Love the result on this job
Hi from Norway you guys !

[gary]

Just take it to a masonry supply place and have them send a sample of the old mortar out to be analyzed. Why guess at it. You will end up with a very good match.

[tiffanybackup]

Thanks for the video, guys! We exposed the brick in our 112 year old apartment wall. Both the living room and the bedroom have a mix of pebbles or small stones and what looks like sand the color of, well sand! It's a light beige color with no grey in it (from what I see). How can I make it match in both color and texture? I've been grinding the mortar to make it nice and smooth. Can I use reuse the leftover sand from grinding it, or no?

[Santos-ekmd]

How about do a vid on DIY steam clean brick pointing?

[DanMolden]

Just like matching stain when puttying wood

[josephnorcalusa]

thank you for sharing, helpful information !!

[CurvedSlightly]

But didn't bother telling us what kind and colour of sand?

[huntress]

How bad is it if I re-point mortared one horizontal line on the outside of my stone foundation wall and the top line of stones on my patio with type s mortar? How bad is the risk of cracking stones or other damage? It is old fieldstone. Should I definitely chip it out and remove it? Does the chipping itself risk damaging the wall?