It's tough to match old concrete

[Sinoed]

As part of the repairs to the masonry and facade I'm having three damaged window sills replaced. They have to be custom made because of a fancy little imprint on the front. Apparently matching concrete that is 120+ years old is proving to be quite the challenge. Adding a bit of black didn't work - it looks like too much grey. I actually think adding tan or brown to the mix might help but I'm not quite sure and my concrete guy is a bit puzzled. Anyone done this before or have any thoughts on what to try?

[Mick_VT]

I have heard that new brick can be made to look closer to old by soaking with black tea... you might try that

[DRJR]

Try mixing brown with a little black. That should get you close.

After the cement has cured, wash it with muriatc acid. This will give you the weathered look.

[Vala]

Will the concrete change color over time?

[Texas_Ranger]

Will the concrete change color over time?

Absolutely, within only a handful of years! I've seen identical concrete pavers mixed (new ones and ones that had been on the ground for less than 5 years) and the old ones were slightly lighter and definitely more beige than grey. Add all sorts of moss and lichen to the equation and you get fairly drastic changes!

[Vala]

Will the concrete change color over time?

Absolutely, within only a handful of years! I've seen identical concrete pavers mixed (new ones and ones that had been on the ground for less than 5 years) and the old ones were slightly lighter and definitely more beige than grey. Add all sorts of moss and lichen to the equation and you get fairly drastic changes!

Might that be something for Sinoed to consider then when it comes to matching?

[Sinoed]

I'm kind of hoping it does fade over time, I think they'll blend better after that. We're going to try a bit of brown and my concrete guy is going to bring the sills over to the house for a check before he pours any more. I never thought it would be this tough.. :p

[DRJR]

Acid wash will give the concrete a weathered look. It should help blend the new crete with the old crete.

Another trick to get aged concrete, is to use colored sand. A mix of red mason sand and grey concrete sand will give you a light grey/tan look. Once washed with acid you will have an aged look.

Playing with sand is actually easier than coloring dyes. Using either will take some experimenting to get what you want.

Remember to keep the color to the darker side. Concrete will get lighter with age.

[Sinoed]

The concrete guy has tried adding a bit of brown and I think they're getting pretty close. He's going to take the test sills over to the house to see how closely they match so my aunt can give him the ok. I'm relatively fortunate, although there are other windows on the street side they're set back above the porch so I don't think you'll notice the color difference as much. The sill being replaced for the kitchen faces the backyard, so you can't really see that one. I hope these work out - I'm guessing they're going to be expensive.