Q) I am interested in knowing if there is a good, long-lasting paint that can be used on a concrete patio and walk that is outside and uncovered.
My concrete had to be patched in several places and I would like to cover up the patchwork. I have about 1,500 square feet of concrete.
What is the best type of paint and how long will it last? Should a primer or sealer be used first? Also, is there any type of concrete topping, not more than half-inch thick, that can be put on top of old concrete? -- D.W.M.
A) I will answer the last part of your question first. Yes, there is a topping that can be applied over old concrete to give your patio and walkway areas a new surface. The topping is applied using a concrete patching material and concrete glue.
There are several brands available. Consult your local masonry dealer for recommendations and be sure to read the instructions of each product carefully prior to making a selection.
If you prefer to paint the old surface you can also do this with success. Careful selection and application of the paint are mandatory.
You will need an alkali-resistant paint made for concrete and masonry. There are several brands on the market which, together with special brushes and rollers for masonry surfaces, have made painting masonry a relatively simple matter.
First, be sure that the surface is clean, that cracks, indentations and spalls are filled, and that the surface has no flaking areas before painting. Wash away all oil and grease; remove dirt and other materials with a wire brush.
If there is a white salt-like material adhering to concrete, stucco or mortar, it is probably efflorescence. This is caused by moisture that dissolves salts in the interior of alkaline materials and carries them to the surface. Efflorescence must be removed before painting or repainting by brushing (do not wet or more crystals will appear). Painting will help prevent efflorescence.
Before painting, apply a colorless water sealer recommended for masonry surfaces.
Selecting a quality paint is important. Remember, concrete is quite alkaline and alkali is not a friend of many paints. Alkaline-resistant paints include latex paints designed for use on masonry surfaces, Portland cement paints, masonry paints and solvent-thinned rubber-base paints.
Each has its advantages and disadvantages. For example, latex paints for use on masonry surfaces can be used with confidence. They come in a variety of colors, are water-thinned and can be applied to a damp surface. In fact, the surface should be dampened before applying the first coat.
Solvent-thinned rubber-base paints are ideal for painting basements, porch floors, swimming pools and walks exposed to weather. They provide excellent resistance to alkali and water penetration and resist abrasion. After an alkali-resistant primer has been applied, the finish coat should be used to resist exposure. Two finish coats are better than one.
Your local paint dealer, or masonry dealer should be able to give you recommendations on specific brands of paint. Send inquiries to Here's How, Copley News Service, P.O. Box 190, San Diego, CA 92112-0190. Only questions of general interest can be answered in the column.