The History of Paint

Paint through the Centuries

For centuries, paint was essentially lead. Ancient Egyptians, Greeks, and Romans made a sort of paint by treating lead with wine or vinegar. Later painters mixed up white-lead paste, then added linseed oil, turpentine, a drier, and colored pigments in oil. Such paint had turpentine, a drier and colored pigments in oil. Such paint had great hiding power, was easy to work with, stuck where it was applied, and weathered well. Unfortunately, it also poisoned people, by skin absorption, respiration, or ingestion (the paint chips tasted sweet). Today, paint with more than .06 percent lead by volume is banned in the U.S.

There's also been a shift away from oil as the base for paint. It began during World War II, when linseed oil and the solvents that cut it were scarce. By the mid-'5Os, synthetic replacements were outperforming natural ingredients. Today, practically all paints consist of some form of synthetic resins or polymers. Modern solvent-thinned paints still work like the old oil-base paints, only more effectively; alkyds (a hybrid word designating the combination of alcohols and acids that produces the synthetic resins) have replaced most or all of the natural oils. Alkyd formulations are comparatively low in cost and have excellent color retention, durability, and flexibility.

But the most dramatic shift has been away from solvent-thinned paints in favor of water-thinned ones. Today, latex is the consumer standard, accounting for nearly 80 percent of the paint sold.

What's in paint? Three components

Pigment gives paint its color and hiding power.

Vehicle is the combination of synthetic resins and oils that surrounds the pigment particles.

It determines cohesiveness (providing the strength for the dried paint film) as well as adhesiveness.

Carrier (often listed as the volatile vehicle) thins the syrupy resins so the paint will flow on; it
evaporates first as the paint dries, and it allows for varying consistencies thicker or thinner.
Water is the carrier for latex paints, petroleumdistillates for alkyd paints.

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Are today's paints better?

Experts disagree. The quality range is much wider, but the best are better and the worst much worse. Paint life span is impossible to predict; there are too many factors

specific to your situation. Be wary of guarantees in judging a brand, see if the paint levels itself
out, showing few brush or roller marks, ripples, or pockmarks. It shouldn't run or sag on the wall during application-the sign of a thin paint (or perhaps you're applying too thick a coat.)

The paint should hide what's underneath it. It should dry hard, to resist denting, scratching,
marring. Hardness correlates with resin content and gloss. Old-timers might swear by linseed oil
base paint, but tests at the USDA's Forest Products Laboratory suggest that today's best choice
for routine outdoor home use is an acrylic latex with a resin content of at least 20 percent.

Paint Gloss: what you get is what you see

Resin makes paint durable, easy to clean, and moisture resistant; the more resin, the higher the gloss. High-gloss paint reflects light, emphasizing defects in walls and ceilings as well as showing
off whatever it coats. (Textured paints and flats break up light; that's why they're used on large
walls and ceilings, particularly if those surfaces are uneven or damaged.

On labels, gloss goes by various names: luster, shine, sheen. Paint can be termed high-gloss, semi gloss, or flat (mat). Semi gloss can be called eggshell, velvet, satin, or pearl, and can range from
nearly flat to very shiny, depending on the manufacturer. There's no industry standard. With enamels, the pigments used should be top quality, with little filler.

Latex glosses may stay tacky much longer than you think. They may feel dry to the touch, but
don't stack things on the newly painted surfpadding:ace too soon, or they may bond to it. Cure can take
two weeks to a month.

Latex Paint: easy to work with, clean up

Once a name for synthetic rubber, latex is now synonymous with water-thinned paint.
The pigment-holding resin particles are held in suspension. Instead of absorbing oxygen to form
a hard coating, the particles actually coalesce into a tight film that is insoluble in water when dry.

Latex is easy to work with. It can be applied to damp surfaces. It doesn't require a wet edge; you can stop mid wall, start later, and never see where you left off. It dries fast, though a full cure can take up to four weeks. Best of all, you can clean up wet paint with soap and water.

You can tell latex quality by the type of resin used:

acrylic is best; vinyl acrylic and other blends next, all vinyl not as good. All are flexible (particularly the acrylics), stretching and shrinking with the wood or whatever they're painted on. On the down side, you can't sand latex especially gloss latex to a desirable texture; it will tear off or melt to a gummy consistency. Latex enamel doesn't level as well as alkyd enamel and won't hold as high a
gloss but a top-quality latex product will hold its gloss better and longer than its alkyd counterpart, especially in areas exposed to weather.

Alkyds:

higher gloss, harder surface Alkyd paint (often called oil-base paint) doesn't dry like latex; oxygen absorbed from the air changes the molecular structure of the solids, so you can sand an alkyd surface- a critical factor if you're using successive coats to provide high glosses. The paint will
also hang on a little harder, because the solvent will carry the paint into the substrate more than water would. On old, poorly prepped surfaces, like chalking walls, choose an alkyd. It will also hold
a higher gloss, and the paint film is more moisture resistant.

On the minus side, alkyds are harder to apply, aren't as sag resistant as latex, are harder to touch
up, and require cleanup with mineral spirits.

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