A: There are several options for patching divots in granite and other natural stones, including two-part epoxy, polyester resin mixed with hardener, and acrylic resin cured with ultraviolet light.
Acrylic cured with light is usually the easiest option for homeowners interested in making the repairs themselves, said Bill Hickey, vice president of sales for Braxton-Bragg (800-575-4401; braxton-bragg.com), a Tennessee-based company with nationwide sales of tools and supplies for installing and caring for tile, stone and concrete. However, the acrylic dries clear, so it’s suitable only when the patch doesn’t need to be tinted. How to know? Hickey recommended filling a hole or two with water or rubbing alcohol. If the divot virtually disappears when the hole is full of clear liquid, clear acrylic is suitable for a patch. “It’s like a magnifying glass” that brings the look of the underlying stone to the surface, he said.
Assuming this test shows a clear patch will work, one option is the ProCaliber Granite and Marble Acrylic Repair Kit, Clear Gel ($29.95 at braxton-bragg.com). The kit includes acrylic, a syringe to get the acrylic in divots, a light to cure the resin and polishing materials. Separately, you should also buy some single-edge razor blades, which are often sold at hardware stores and home centers with painting supplies. Do not use utility knives; they will scratch granite, while razor blades, used correctly, will not.
If you use the kit, Hickey recommends cleaning the countertop with rubbing alcohol, then slightly overfilling a divot with the resin and shining the light on it. This will harden the acrylic, typically within two or three minutes, he said. After the acrylic begins to harden, but before it is completely hard, scrape back and forth with a sharp razor blade held at a 90-degree angle to the surface of the stone. This will gradually shave off the surface of the patch, leaving it level with the stone. Once the patch is so smooth that it feels the same as the surrounding stone when you rub your fingers across the surface, you are ready for the final step: polishing. With a soft cloth or paper towel, rub some of the polishing cream in the kit over the patch until it is as glossy as the rest of your countertop.
If your test with water or rubbing alcohol showed that a clear patch won’t do, you’ll need to decide between epoxy and polyester. Epoxy forms a stronger bond. But for filling holes, the polyester is typically plenty strong. The polyester is also less tricky to use because it hardens even if you don’t use the precise proportion of hardener, which can’t be said for epoxy. And polyester costs less. So for most homeowners, it’s an obvious choice. Akemi Marmorkitt 1000 Transparent Knifegrade Adhesive is one example; Tenax is another popular brand. Braxton-Bragg sells the Akemi product in a one-quart can with hardener for $23.50. A coloring kit with tubes of eight colors costs $44.95, or a tube of a single color is about $6. If the divots are mostly in black areas of your countertop, you might be able to get by with a tube of black. Although labeled as transparent, the resin is really a honey color. Akemi makes similar products that work better if you want light-colored patches. There is, for example, a platinum version that cures to a light gray. “Knife grade” is a term that other manufacturers also use to distinguish patch products that have a putty consistency from those that are pourable liquids. For countertop repairs, get knife grade.
Use the same razor blade technique to trim polyester or epoxy patches until they are level with the countertop.
As for your travertine shower bench, you could use the same patch materials, but you will probably need a light-colored substance. Hickey recommended K-Bond Polyester Knife Grade Transparent Adhesive, which Braxton-Bragg sells for $14.95 a quart, with a tube of hardener included. (Curiously, with polyester adhesives, the more hardener you use, the less hard the resulting patch is. Check labels, but the typical amount of hardener is only about 2 percent of the mixture.) Coloring paste costs $6.49 for a single color or $59.87 for a kit of 10.
Another option for travertine is to use a cement-based, unsanded grout as a filler.
Travertine is porous, so you need to be far more careful not to smear patch material across the face of the stone than you do when patching granite. Take the time to spread blue painter’s tape around the perimeter of each hole beforehand. Travertine is usually honed, not polished, so there is no need to buff the patch.
Whether you’re working on granite or travertine, if you need a tinted patch, one of the most difficult steps is mixing a custom shade that’s a perfect match for your stone. It’s an art — and one of the big reasons pros often do a better job than homeowners, even if they use identical products. But, of course, a pro job costs more. Surface Link, in Chantilly, Va. (800-482-1774; surfacelink.com), works with about 40 countertop restorers across the country. Its minimum fee is $295, said John Vatis, technical director and owner. For that price, you’d typically get numerous holes patched.
Patching a countertop or shower bench does not affect sealant used on the rest of the stone. Many installers recommend resealing stone every year. So if that’s what you’ve been doing, just keep on with your routine.
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