Q. We had an outside stone wall repaired. The mortar is very white and does not match the old, gray mortar. Is there any way I can darken the look?

S.G.

A. When I ran into this situation, I asked the mason to tint the mortar to match the existing shade. Matching mortar is crucial and takes time, which can add to the cost. A little extra care makes all the difference between a repair that disappears and one you can see a mile away. My mason used white, tan, and different brands of gray mix and a black mortar tint to dull the color of the new mortar, as well as orange and white sand.

Since your mortar is already in place, you can try to tint the new stuff, but even as I type this I’m cringing. Because nearly 70 percent of a mortar’s color comes from sand, it is very important to match the composition of the old application as closely as possible.

Making stains

My mason told me that for an aged look, you can brew a stain with tea or coffee and test various strengths on an inconspicuous spot to get the best color match before moving on to larger areas. Apply the stain on the test area with a soft paintbrush using different stroke lengths, then rinse it off and evaluate. Allow the area to dry completely and compare before proceeding to stain the rest of the mortar.

Here are a few recipes, but remember: Please protect your skin and eyes when mixing chemicals.

■ For a reddish- or rust-colored stain, soak common nails in water until they rust, or use iron sulfate, mixed at the ratio of ¼ cup in ⅔ cup of water.

■ For a greenish-blue, mix ¼ level cup copper sulfate with 1 cup of warm water.

■ For a gray-brown-black, mix ¼ level cup manganese carbonate, 1 tablespoon potassium dichromate, and ½ cup plus 2 teaspoons of muriatic acid.

Q. I know I have ceiling mold. I can smell it. I had a new roof put on, but continue to have problems. Should I call in a mold specialist?

TDARR61

A. You mentioned that you have a new roof. Did you have leaks? If you had water damage and you’re sure the smell is mold, then, yes, have a company that specializes in it do an inspection.

Can you access your attic to get a visual on that area? Many times mold is visible on the underside of the roof sheathing or on the tops of the ceiling wallboard.

Rob Robillard is a general contractor, carpenter, editor of AConcordCarpenter.com, and principal of a carpentry and renovation business. Send your questions to homerepair@globe.com or tweet them to @robertrobillard.