We had to tear out part of an old rock wall to install a new door and window and now having trouble matching the mortar to replace the rocks. The house is very old and was probably cemented back then. We have tried mixing half and half mortar/concrete, using bleach among other things which dries alot darker than the original. Any suggestions?
Re: matching mortar/concrete
Depending on how much area you are needing to do, there is a product at Home Depot that might work for you. It is a pre-mixed adhesive grout material. They have 3-4 colors that I have mixed together to make another color. It comes in 1 qt. containers. If you have alot to do you might consider using it only as a top coat over the regular concrete about 1/8 of an inch thick, just for color.
Another suggestion is to match the color of the old concrete in a flat latex paint. Thin it down to the consistancy of stain and kinda "faux" color it that way.
Be sure that the old, existing concrete is clean of mold and mildew. Take a spray bottle with bleech in it and mist the old concrete next to the area around the new opening. You might want to feather it out, if it's a big wall, to keep from doing too large of an area. If you're up to the task, go all of the way to the corners of the wall in both directions. (For that use a pump up garden sprayer) After the bleech sits for about 10-15 minutes, rinse the wall well with a pressure nozzle on a garden hose. (don't let the bleech dry on the windows) You will be suprised how much the color will change by killing the mold and mildew that is in the pores of the old concrete.
If you have not done the concrete work yet, there is also a colorant for concrete in the same department as the adhesive grout I mentioned. Do some sampling first before mixing up a big batch.
Last edited by J Roper; 10-13-2008 at 04:09 PM.