McPherson Quality Painting and Water Proofing

McPherson Painting

by Mike McPherson

What is low odor paint? Does it work? Read on.

Paint Odor

Until recently, the strong odor in latex paint was like a lot of things in life - it was unpleasant, but you put up with it to get the job done.

The primary odor-causing agent in latex paint has always been the solvent. But things are changing. Today, you can buy low-odor interior latex paint that is essentially solvent-free, and industry experts say that low-odor exterior paints should debut in the near future. Certainly, this is a boon for painters and customers everywhere who are bothered by chemical odors. Yet it presents the problem of discerning the difference between paints that are nominally low-odor - those that meet federal specifications for solvent content - and new varieties of paint that are formulated to have almost no solvent. Both types of paint form a high-quality, long-lasting film, but the solvent-free variety is much more pleasant to use, especially if you're sensitive to chemicals.

Chemistry In The Air

To understand the difference between low-odor paints, you have to delve into the arcane subject of paint chemistry. Let's start with a basic definition of paint. It's nothing more than a mixture of pigment and binder that's dispersed in a solvent. When the mixture is applied to a surface, the solvent evaporates into the air, but the binder and pigment remain. The binder is a glue like material that forms a film that clings to the surface. The pigment, or color, is dispersed in the film and acts as the evaporating solvent that gives paint its odor.

That's all there is to basic paint. But latex paint is a bit more complicated. Like all paint, it contains binder, pigment and solvent, but it has another ingredient - water. Many people call the water in latex paint the solvent. But strictly speaking, the water does not dissolve anything. It merely separates and suspends the spherical globs of binder and pigment particles. This is why you may have heard latex paint referred to as an emulsion. It's a mixture in which particles of a substance are immersed, but not dissolved, in a liquid. In latex paint, the binder particles are as hard in the can as in the final film. It's no coincidence that paint chemists refer to binder as a solid. The binder gives paint its resistance to abrasion, called scrub ability. And to a large degree, it's responsible for the paint's shine and its resistance to ultraviolet rays. A chemically sophisticated binder has more binder particles, which makes the paint more expensive. McPherson Quality Painting uses only the highest quality materials.

Traditional latex binder is so hard that it needs to be temporarily softened with solvent to allow the binder globs to stretch and become oval-shaped. These oval globs can then form a film with pigment trapped inside. This process is called coalescence. As it takes place, both the water and the odor-causing solvent evaporate. High-quality latex paint requires no more than 1% to 7% coalescing solvent per gallon, while the new low-odor latex paints have less than 1% and are considered essentially solvent-free. These paints have soft, self-coalescing binders that don't require solvent.

Solvent-Free Characteristics

Self-coalescing binders are certainly a major chemical breakthrough, but paint manufacturers told us that there are trade-offs. The softer binders don't provide the hardness or scrub ability that other binders do. Also, solvent-containing latex paint is available in a gloss that rivals oil-based paint, but solvent-free latex is available only to the semigloss level.

And while solvent-free latex paint can be tinted to any color, the colorants contain solvents, and the darker colors contain more solvent than the lighter colors.

There are also other chemicals, aside from solvents, that contribute to latex-paint odor. As a class, these materials are known as paint additives. For example, amines, which are materials that are chemically related to ammonia, are added to paint to improve its chemical stability across a range of temperatures. This is especially important in latex paint, because even the best-quality latex is 65% water. So you may still notice a slight ammonia odor. Other materials that contribute to paint odor are mildeweides and chemicals called rheology modifiers. These are the substances that help the paint form a smooth coating. Finally, no matter what kind of paint you use, you're liable to notice some odor immediately after applying it. This phenomenon has less to do with the paint than the substrate. If you apply any liquid over a surface, the surface itself will release an odor. Some of the odor associated with paint is really the smell of the surface below it being wetted with water or solvent.

So how do you choose a solvent-free latex paint? Chances are that if you walk into a paint store or home center and ask for a low-odor latex, you'll be told that all latex is low-odor. If you try to clarify this by asking for solvent-free latex, you may get the same reply. This is not necessarily evasion on the part of the salesperson. Paint is still largely considered a solvent-borne material, and when you compare it to oil-based paint and other coatings, any latex paint is low odor and has few petroleum solvents.

So if you can't get any information at your local paint store or from your prospective contractor contact  for tips on "Solvent-Free Paint Shopping" and for the names of some readily available solvent-free paints. Try Kelly Moore or Home Depot.

Low-odor Application

Okay, you've decided to give these new low-odor paints a shot. It's only natural to wonder whether applying them will yield results different from the standard latex paint you know so well. You'll be relieved to know that there isn't a lot difference with these paints in terms of application or cost when compared to traditional latex paint. The low-odor variety is a premium-quality product, so you'll probably pay in the range of $30 to $45 per gallon for it, depending on where you shop. The paints provide an average of about 400 sq. ft. of coverage per gallon—the industry standard for a gallon of high-quality latex paint applied to an evenly textured and not overly porous surface. As obvious as it sounds, don't overlook surface preparation when applying these paints. The fact that the paint is a premium product doesn't mean it will bond well to a surface that is dusty, greasy or covered with mildew. It's really just common sense. Clean the surface if it needs it, prime it if it is in poor condition and mix the paint thoroughly or have it mixed.

Finally, apply the paint without overspreading it. You can roll low-odor latex with a 3/8-in. nap roller, and cut into corners using a synthetic bristle brush. It's just that simple. And you'll be able to breathe easier in the process.

Graphic of proportions of materials in a can of paint

Figure 1 can

can of paint20% binder, 15% pigment, 65% water and additives.

A can of high-graded latex paint contains 20% binder by volume. In traditional latex paint, there is 1% to 7% solvent dissolved into the binder. This solvent is largely responsible for giving latex paint Its odor. New, low-odor varieties of latex paint are essentially solvent free, though they contain about the same amount of binder.






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