Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: SUNDAY, June 26, 1994                   TAG: 9406300020
SECTION: HOMES                    PAGE: D1   EDITION: METRO 
SOURCE: Popular Mechanics
DATELINE:                                 LENGTH: Medium

HELP FOR STAINS IS AT THE HARDWARE STORES

A: There are a number of products on the market that will solve your problem. They are available at hardware stores, paint stores and home centers, and are referred to as water stain blockers or sealers (also called stain-blocking primers and stain-blocking sealers).

The stain-blocking sealer-primer is applied to the ceiling with a brush or roller, or it is sprayed on (it's available in aerosol cans). After the sealer-primer is dry, paint the ceiling.

Q: I've heard the term ``marine boot glazing'' applied to home windows. Can you tell me what this is, exactly?

A: You would think you walked into a boating supply house to hear your local window retailer talk about marine boot glazing. But the term is well suited to the high and dry. It refers to a flexible vinyl boot which is stretched around an insulated glass lite (often referred to in the window trade as an IGU, for insulated glass unit). It prevents moisture and air penetration. The boot is installed at the factory or can be re-installed with a new IGU in case the existing one is broken by a flying object, such as a fish, for instance.

Q: My concern involves the black mortar used on the brickwork of my 10-year-old home. This mortar was used to accent the bricks.

When it was new, the mortar was very black. However, after the first year, it turned gray. Now, after 10 years, the sun and the weather have turned the mortar almost neutral.

Is there anything I can do to restore the black? In every home I've seen with similar mortar, it has become faded.

A: Although nothing can be done to restore the black in the original mortar, there is something you can do to produce black mortar joints.

You can either stain the joints or tuckpoint them. Both of these methods are tedious and labor-intensive, so, unless you do the work yourself, it can become quite an expensive undertaking.

The original mortar mix probably had carbon black to produce the black color rather than a mineral oxide. They say that carbon black is sensitive to ultraviolet light, not stable, and has a life of about seven months to a year.

If you want to tuckpoint, you will have to grind out the existing joints to a depth of about five-eighths of an inch and then fill them with new mortar containing a black mineral oxide pigment.

The other method of producing black joints is to stain them using a water-repellent, penetrating masonry stain. The stain can be applied using a one-half-inch brush. You must work carefully, however, so as not to smear stain on the bricks.

To submit a question, write to Popular Mechanics, Reader Service Bureau, 224 W. 57th St., New York, N.Y. 10019. The most interesting questions will be answered in a future column.

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