PaintPRO Vol 3 No 4

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Related Readings:
Ceramic Paints
Ceramic Pigments & Paints
Winning White Paint
Quality Paints
Elastomerics
Epoxies
Other articles in this issue:
Choosing Quality Wallpaper
Metallic Paints
Surface Prep for Wallpaper Removal
Colored Plasters
Estimating a Paint Project
Contractor Profile: Hennig Mural Design
Paint Product News
Painting Tips
 
PaintPRO Archives
USG Paint

 

 

Plaster, Integrally Colored Plaster

New products make integrally colored plastering a whole lot easier.
By Gail Elber

About three o’clock in the afternoon, drywall will break your heart. A slanting sunbeam can reveal ripples in even the best-finished wall. And if your wall is in a public space such as a restaurant or office, it’s vulnerable to bumps and scuffs, so it requires constant touchups. As a result, homeowners and business owners looking for something classy and durable are renewing their interest in drywall’s ancestor, plaster. But conventional gypsum-based plaster requires several layers with a long curing time and — well, a plasterer. Likewise, to apply lime-based Venetian plaster, a technique much in demand now, you need training to produce its characteristic multilayered colors and marble-like sheen. Fortunately, several alternatives offer some of plaster’s warm, soft look, integral color, and durability with less expense of money and time, and some of them are well within the abilities of anyone who can apply drywall texture. If drywall texturing is part of your business, consider some of the integrally colored texture options you can offer as an alternative to paint.

USG ApplicationsAn applicator applies the USG Plaster BonderClear to a wall whose trims have been masked off and joints finished with SHEETROCK® Brand Wallcovering Primer. These Steps prepare the wall to accept the Decorative Interior Finish and help ensure a beautiful uniform final effect.

Decorative Interior Finish System
The Decorative Interior Finish System from USG provides the look of integrally colored gypsum plaster but is easier to apply. It can be applied over drywall finished to as little as level 2 (joints taped with one coat of compound). The system consists of a coat of plaster bonder and a colored layer of USG’s Diamond veneer plaster. After knockdown troweling and burnishing, you apply a sealer.

Casey Coates of Western Partitions Inc. in Tigard, Oregon used DIFS to create a two-tone finish at Destination Harley-Davidson, a motorcycle dealership. In the past he had experimented with adding latex paint tints to veneer plaster, but he hadn’t been able to match the color between batches. Coates’s estimator and USG rep Randy Novak happened to share an interest in Harleys, so when the local dealership was doing some remodeling, they got owner Ed Wallace, Jr., interested in DIFS, and Coates agreed to experiment with it.

Wallace picked out a color that complemented his floor tile from USG’s standard color chart. USG delivers the necessary colorant premixed in a package that you add to the compound when you mix it with water. In addition to the standard colors, the company will premix custom tints, or you can brew your own. USG has experience only with Colortrend colorants, but any universal tints should work.

USG Mixing compoundAfter the bonder has dried to the touch, one member of the crew mixes the decorative finish. Consistent amounts of water, DIAMOND® Brand Interior Finish and colorant are mixed in a five-gallon bucket using a heavy-duty drill with a joint-compound mixing paddle.

Coates’s crew applied a single layer of DIFS, then burnished it with a trowel to create darker highlights. Compared with coloring his own plaster, Coates says, “This is a lot less labor-intensive, easier to use, and has less room for error.”

Mike Watts of G&W Painting in Salt Lake City has done four jobs with DIFS and has two more coming up. Experienced with decorative and faux finishes, Watts has used DIFS to get various effects. “I’ve experimented with a raw umber glaze over the top to give it an aged look,” he says. “We’ve burnished it to a smooth finish, then after it dried we troweled it with a magnesium hawk to leave marks on it and then sanded it down to lighten it.” On an upcoming job, he plans to apply alternate trowelfuls of two different shades.

Having put some test boards through a torture test, Watts gives DIFS high marks for durability in the face of nail holes and bumps. To make repairs easy for the client, he spreads out a portion of the material to dry after the job, then grinds it to a uniform fine texture and leaves a plastic bag full for the client. The client can mix a little with water to fill a nail hole, and it matches nicely.

Applying Decorative Interior FinishThe Decorative Interior Finish is applied to the wall to a thickness of 1/8-inch, starting in the corners and moving outward.

Clay plaster
Clients who have been doing their homework may ask you about clay plastering, sometimes called “earth plastering” or “natural plastering.” Though it’s a little out of the mainstream, it’s definitely not out of the question. Originating with ancient adobe and cob houses, the technique has been adopted by modern cob and straw-bale builders. But clay plaster can also be used on drywall, an application that’s popular in Europe. Europeans like the fact that manufacturing clay plaster is easy on the environment. Also, clay doesn’t irritate people who have environmental sensitivity disorders.

To make your own clay plaster, you start with a clay slip (often potters’ clay), then mix in sand and chopped straw, plus a protein binder, such as eggs or casein. The mixture is troweled on in thin coats. It’s actually more forgiving than gypsum or lime plaster because it doesn’t set up while you’re working; each coat takes a couple of days to dry. The final coat, in which straw is omitted and linseed oil is added, is burnished to a smooth and durable finish. The color is pinkish to brownish, depending on what clay you can get. Bits of mica or straw can be added to the finish coat for sparkle. You can find recipes in natural building books and Web sites, or attend a natural building workshop.

If paddling in raw eggs doesn’t sound like fun, you’ll be happy to hear that Tierrafino, a user-friendly preformulated clay plaster from Holland, is available in the United States from Hopper Finishes in Phoenix, Arizona.

USGTierrafino comes in five earthy colors that can be mixed to produce others. It can be troweled or even sprayed over Level 2 finished drywall. Ground mother-of-pearl, straw, or other particles can be added to the top coat for visual interest. After the surface has dried, it must be sponged off, then smoothed with a soft brush, to eliminate dust.

Don’t be put off by the softness of clay plaster — it’s actually quite durable. The surface yields to a fingernail, but scuffs or cracks can be repaired by wiping the surface with a damp sponge, then smoothing it with a soft brush. When Anne Marie Holmes’ cabin in Dexter, Oregon was flooded, the clay-plastered drywall suffered only a water-line. The plaster and drywall remained sound. As with DIFS, leave a little mix with which the homeowner can fill nail holes and the like.

Don’t paint your next job
Residential and commercial clients are drawn to colored plaster not only because of the practical advantages — durability, soundproofing — but because of the material’s intangible warmth. Now that a new wave of colored textures has made it easier to create this effect, you may find that it’s worth your while to offer your customers an alternative to paint. Go ahead — encourage your customers to yearn for the look of a Tuscan farmhouse, an adobe hacienda, or an African palace. But let’s just hope that fashionable decorators never rediscover the widespread ancient practice of plastering with dung.

Other plasters
DIFS and clay plaster are easier to apply than conventional gypsum plaster or Venetian plaster. Those materials must be pressed into the wall in multiple coats with special troweling techniques, then troweled hard to bring the fine particles to the surface and sometimes burnished to produce a gloss.

Plastering is a trade that takes time to learn. If you’re interested, some faux finishing schools offer plastering instruction. Or seek an alliance with a plasterer. Meanwhile, if you find yourself talking about plasters to clients and vendors, here are a few terms that you’ll need to know.

Setting-type compounds
Stucco: Based on Portland cement, which contains lime (calcium carbonate), clay, sand, and other ingredients. As in concrete, mortar, and grout, the lime undergoes a chemical reaction (setting) when mixed with water, generating heat and creating a hard mineral compound. What we call stucco in North America is a coarse-grained compound meant for exterior application over expanded metal lath or masonry, but some fine-grained Venetian plasters are also called “stucco.” Make sure you and the client are alluding to the same thing. You can apply colored exterior stucco indoors, but it’s not going to look like the Venetian plaster they saw in Metropolitan Home.

Gypsum-based plaster: Based on the mineral gypsum (calcium sulfate dihydrate), which is heated during manufacture to remove water from the molecule. In this case, it’s the gypsum that reacts with water, generating heat and producing a hard mineral surface. It’s softer than Portland cement. Plasterers color it with universal tints, but it’s difficult because the material is so white.

Venetian plasters: Based on very fine particles of ground limestone and marble, they’re meant to be colored.

Synthetic plasters: These combine stucco, plaster, or Venetian plaster with acrylics to improve workability and water resistance.

Setting-type drywall taping compounds: Known as hot mud, they harden in less than an hour. Based on chalk, a soft form of calcium carbonate, they’re softer than gypsum plaster, but can be used to create textures where wear and tear will be low.

Drying-type compounds
Drying-type drywall compounds: Based on vinyl instead of on minerals, they harden overnight by evaporation. They’re not hard enough to use for texturing.

Clay plaster: Based on clay, a hydrous silicate of aluminum. Clay plasters also harden slowly by evaporation, forming a soft but easily maintained surface.

 
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