Grout Grows Up

The way that grout is applied to ceramic tiles today would be familiar to a tile setter from ancient Rome. The difference is what's in that grout. Recent years have seen the development of high-tech grout products: additives that make grout resistant to stains and mold; lightweight polymers that make grout easier to work with; ingredients that make it easy to match grout color to tile color; even silica that makes grout sparkle.

A number of manufacturers now offer mold inhibitors. These include BioBlock from Mapie Americas (www.mapei.com) in Deerfield Beach, Fla., which is formulated to combat mold, mildew and bacteria. However, many builders don't realize that mold inhibitors tend to have a limited effective lifetime. "Mold inhibitors in cement grouts will eventually oxidize, and they won't provide long-term mold prevention," says Gray LaFortune, director of the Los Angeles-based Ceramic Tile Institute of America.

LaFortune says that a better way to get long-term mold resistance is simply to follow the grout manufacturer's mixing instructions, the most important of which is not to put too much water in the mix. "Most people overwater the mix, so the grout becomes porous [when it dries]. This allows organic material to enter the grout and encourages mold growth," LaFortune says. He says that epoxy- or resin-based grouts don't absorb water and are more mold-resistant than cement-based grouts.

Epoxy- and resin-based grouts are also easier to work with, say some tile setters. Peter Gowen, repair specialist with AGS Tile & Stone in Sacramento, Calif., says that he enjoys working with Mapie's epoxy grouts. "Mapie epoxy grout is a two-part mixture instead of the more common three-part epoxy grout," Gowen says. "In addition to being easier to mix, it seems to have a longer working time."

Gowen also likes the new Prism line of lightweight grout from Custom Building Products in Seal Beach, Calif. A seven-pound bag of Prism has the same volume as a typical 25-pound bag of cement-based grout and covers as much area, according to Gowen. "Its lighter weight makes a big difference [to the tile setter] at the end of the day," says Gowen.

Some additives do double duty. Sealers are designed to protect tile and grout from staining, but a new surface sealer called Enrich-N-Seal, from Aqua Mix in Corona, Calif., can also make post-grouting cleanup easier. "The polymer additive seals the grout and also takes away the powdery look of slate, marble, travertine, limestone, granite and other natural stone tiles," says Christine Jenkins, Aqua Mix corporate training manager. When applied prior to grouting, Enrich-N-Seal also reduces the bond between the grout and the tile surface, so excess grout can be more easily wiped off after it dries.

Aqua Mix has also modified its Grout Colorant so that it adheres better to different types of grout joints. This waterborne epoxy colors, seals and rejuvenates existing grout joints and can be used on new installations where the grout has dried to inconsistent shades. It is available in 99 standard colors and provides a seal that can last up to 15 years, according to Jenkins. Custom colors are also available.