Concrete Tiles Have Taken a Powder
Question: We put concrete tiles in our backyard in a large area. They look like red quarry tiles, 12x12, but they are made of concrete.
After a year they started to look bad with white stuff appearing on the surface. We applied a polyurethane coating and it improved the look for about six months. Now there are areas that have the skin peeling off and other areas where it is back to the white concrete look.
Can you suggest anything to clean it up and make it look better and/or to apply to the surface to make it shiny. We’ve used muriatic acid and various chemicals.
Answer: The problem of the “white stuff” is this: The sun beating on the concrete draws up the ground water beneath the concrete. As the moisture rises through the concrete, it frees and brings to the surface the lime or calcium carbonate (white stuff).
There is a product called Sinak that claims to remedy this situation. Sinak penetrates concrete and neutralizes the calcium, forming what the manufacturers call cold-process glass. In essence, it allows the concrete to “breathe.”
One problem for the do-it-yourselfer is it comes in minimum five-gallon containers, and a gallon should cover between 120 and 150 square feet, so you may have to buy more than you need. Retail prices range from about $13 to $17 a gallon.
Another problem is there are several types of Sinak, each with a specific use, so it’s important to get the right product for your concete tiles (based on density of the concrete, etc., so get whatever information you can from the contractor who installed the tiles).
And it is important to follow directions with this product.
You might seek guidance and get more details about availability from Sinak at 861 6th Ave., Suite 411, San Diego 92101.
Before doing anything, however, you must get the polyurethane coating off the concrete. I should think another go at muriatic acid is called for, following directions carefully as you would with any acid product.
You might scarify the polyurethane coating before using the muriatic acid.
Q: We have a small cottage on the beach. The exterior is a gray, weathered look. We originally are from the Outer Banks (North Carolina), where there are a lot of houses with that old gray look, so that’s what attracted us to this one. Our family has grown and we want to add on to the cottage, but we don’t know how to aesthetically tie-in the new addition with the existing one. Should we paint it or just sit tight and let it weather?
A: During the years it would take Mother Nature to weather the addition to your satisfaction, the existing cottage might weather itself to the ground.
There’s no need to wait, however. You have at least two alternatives: One is to build the addition in rock or use artificial-rock facing, carrying it over to the foundation or some other part of the existing structure for the aesthetic tie-in.
Or, if you leave a natural wood exterior on the addition, there’s a product on the market that’s designed to give a natural driftwood look. It’s Cabot’s Bleaching Oil, manufactured by Samuel Cabot Inc., a firm that has a factory at 23284 Eichler St., Hayward, Calif. 94545.
Robert L. Marini, marketing manager, points out that there’s no guarantee the bleaching will produce a matching gray shade, but the calcium hypochlorite in the product will bleach the pigment from the wood, producing in about six months a silver-gray effect.
The only problem is: If the new weathered look does not match the old weathered look, you must wait at least two years before staining or painting the addition. At that time, you could paint the entire structure a uniform color.
