PAINTS AND STAINS
Almost every kind of surface, from drywall to concrete, needs protection from the elements. These damaging elements can range from raging blizzards to innocent looking sunlight on a bed room wall. The full total thickness of the paint that ends up on the exterior of your residence is usually about one tenth the thickness of your skin, and interior paint is even thinner. We ask a whole lot of that coating of skin. What it can do depends on a number of factors, like the quality and brand of paint or stain, and how well the areas are prepared and painted.
Paint and stain should be durable, resisting fading and abrasion and allowing repeated washings. Interior paint should go on with little spattering. An excellent interior stain or clear coat should resist fading, peeling, or yellowing, and also be easy to keep, free from impurities or waxes that could collect dirt and make cleaning or recoating difficult. Exterior paints should dry with a toughness that resists deterioration from all types of exposure, and an elasticity which provides for constantly expanding and contracting surfaces. With their thorough penetration and resistance to ultraviolet (UV) light, the stains and finishes on your home's outdoor surfaces should give a similar high performance.
The History of Paint and Stain
The oldest known paint was used by the painters of Lascaux, who ground natural pigments with water and a binder that may have been honey, starch, or gum. You may be wondering why these cave paintings have lasted thousands of years while the paint on the south area of your property is peeling after only three winters. Here's why: The frequent mild temperature, humidity, and dark interiors of caves are ideal preservatives. Your home, on the other hand, is subjected to a myriad of weather and conditions.
The Egyptians knew as soon as 1000 B.C. that paint could protect as well as decorate. Beeswax, vegetable oils, and gum arabic were heated and mixed with Earth and seed dyes to paint images which may have lasted thousands of years. The Egyptians used asphalt and pitch to maintain their paintings. The Romans later used white lead pigment, making a formula that could exist almost unchanged until 1950.
The Chinese used oil from the Tung tree to cement the Great Wall, and to preserve wood. The Chinese used gums and resins to make sophisticated varnishes such as, shellac, turpentine, copal, and mastic. The formulas and applications for those varnishes also improved little during the centuries.
Milk paint dates back to Egyptian times, was widely used up until the late 1800’s when oil-based paints were introduced. Odorless and non-toxic, milk paint today is being revived as an alternative interior paint. Cassein, the protein in milk, dries very level and hard, and can be tinted with other pigments. Like stains, milk paint has to be covered with a wax or varnish, which is very durable.
Created from hogs' bristles, badger and goat hair, brushes also improved little for several centuries. Bristles were hand bound, rosined, and greased, then hand laced into the stock of the brush. Hog's hair brushes, called China bristle brushes, remain a preferred brush for oil-based paints.
Pigments originally originated from whatever bore a color, from ground up Egyptian mummies to road mud. Most mineral or inorganic pigments originated from rust, potassium, sea salt, sulphur, alum (aluminum), and gypsum, amongst others. Some extravagant works incorporated precious stones such as lapis lazuli. Hundreds of organic pigments from plants, insects, and animals made up all of those other painter's palette.
Paints and stains changed little from the time of the Pharaohs to the Industrial Revolution. A book on varnishes published in 1773 was reprinted 14 times until 1900, with only modest revisions. However, the colder climates of northern Europe have brought about the necessity for more durable paint, and in the 1500s the Dutch artist Jan van Eyck developed oil-based paint.
Starting during the Middle Ages lead, arsenic, mercury, and different acids were used as binders and color enhancers. These and other metals made the mixing and painting process unsafe. Paints and varnishes were usually mixed on site, where a ground pigment was mixed with lead, oil, and solvents over sustained high heat. The maladies that arose from dangerous exposure were common amongst painters at least before late 1800s, when paint companies began to batch ready mixed coatings. While exposure to poisons given off through the mixing process subsided, exposure to the harmful materials inherent in paints and stains didn't change much until the 1960s, when companies ceased making lead based paints.
World War I forced the U.S. painting industry to modernize. Manufacturers had to find a replacement for the natural pigments and dyes that came from Germany. They started out to synthesize dyes. Today many pigments and dyes are chemically synthesized.
Enhancements in the painting industry have extended well beyond pigments. Water-based latexes have gained in acceptance as a safe, quality option to oil-based paints. Latexes have evolved from simple "whitewashes" to highly advanced coatings that can outlast oil-based products. Both oil-based and latex coatings are emerging yearly with noteworthy improvements, including the ground metal or glass that's now added to reflect destroying UV light.
A milestone in the evolution of coatings occurred in the early 1990s with the introduction of a new class of paints and stains known as "water borne." Created by the necessity to adhere to stricter regulations, water borne coatings reduce the volatile organic ingredients, or VOCs, found in standard paint and stains. Dangerous and flammable, VOCs evaporate as a coating's solvent dries. They could be inhaled or assimilated through the skin, and create ozone pollution when subjected to sunlight.
STAINS AND PAINTS... THEIR CHEMISTRY Paints and stains contain four basic types of ingredients: solvents, binders, pigments, and additives.
Solvents and Binders
Solvents are the vehicle or medium, for the materials in a paint or stain. They determine how fast a finish dries and how it hardens. Water and alcohol are the key solvents in latex. Oil-based solvents range from mineral spirits (thinner) to alcohols and xylene, to napthas. The solvent also includes binders, which form the "skin" when the paint dries. Binders give paint adhesion and toughness. The expense of paint will depend on in large part upon the quality of its binder.
Because water is the vehicle in latex paint, it dries quickly, allowing for recoating the same day. The odor that you notice when by using a latex paint or stain is the "flashing," or evaporation, of the binder and solvents. The binders in latex are minute, suspended beads of acrylic or vinyl acrylic that "weld" as the paint dries. Latex enamels contain a higher amount of acrylic resins for increased hardness and durability.
Alkyds and oil-based paints are simply the same thing. The word alkyd comes from "alcid," a combo of alcohol and acid that acts as the drying agent. Both have the same binders, which might include linseed, soy, or Tung oils. Oil based and alkyd enamels may contain polyurethanes and epoxies for extra hardness. Alkyd paints come in powerful combinations such as two part polyester-epoxy for industrial use and a urethane customized alkyd for home use. Urethane boosts resilience.
Water borne coatings use a two part drying system: water is the drying agent, and oils form a hard-drying resin. These new coatings match and sometimes out perform their oil-based cousins. They resist yellowing, are more durable, require only water clean-up, have little odor, and are non-flammable. One disadvantage: They swell wood grain and require sanding between coats.
Paint and Stain Pigments
Pigments are the costliest ingredient in paint. Besides providing color, pigments also impact paint's hiding power - its ability to protect an identical color with as few coats as it can be. Titanium dioxide is the primary and most expensive ingredient in pigment. Top quality paints not only have significantly more titanium dioxide, but also more finely ground pigment. Inexpensive paints use coarsely ground pigment, which doesn't bind well and washes off more easily.
Paint and Stain Additives
Additives regulate how well a paint contacts, or wets, the surface. In addition they help paint flow, level, dry, and resist mildew. Oil is the surfactant, or wetting agent, in oil-based paint. These paints have a natural thickness and capacity to flow and level; they go on smoother than latex and dry more slowly, so brush stridations have more time to smooth out. That is why oil-based paints have a tendency to run on vertical areas more than latexes do.
Latex paint has been playing catch up with oil-based paint over time. Today many latexes outperform oil-based paints and primers, thanks to thickeners, wetting agents (soapy substances that are also called surfactants), drying inhibitors, defoamers, fungicides, and coalescents. Defoamers keep latex paint from bubbling and leaving pinpricks (called "pin holing") in the paint as it dries. Bubbling is triggered when the soap wetting agent rises to the top as it dries. The better the paint, the less pin holing you should have. It used to be that if latex paint was shaken at the paint store you would have to allow it to settle for a couple of hours. This is no longer the situation with better paints, that can be opened and used right from the shaker with no danger of pin holing.
Coalescents help latex resins bond, especially in colder weather. Oil-based paint, since it dries slowly and resists freezing, can stick and dry in temps from 50°F to 120°F. With added coalescents and, believe it or not, antifreeze, some latexes can be employed in the same temperature range, and even lower. Some outside latexes can be properly applied at temperature ranges at only 35°F. Companies including Pratt & Lambert, Pittsburgh Paint, and Sherwin Williams have removed the surfactants to help their latex paints be applied in lower conditions. As the wetting agents have been removed, the latex dries faster.
UV blocking additives have been put into paints and stains to help slow deterioration. Sunlight is responsible for a lot of the breakdown of any covering. It fades colors, dries paint, and increases the expansion and contraction process which makes paint crack and peel off. UV blockers in paint may consist of finely ground metals and ground glass which is currently being added for even greater reflection of natural sunlight.
If you reside in an area with lots of humidity, rainfall, and insects, you may need to consider adding a biocide or fungicide to your paint. Biocide deters insects, and fungicide counters mildew. Many coatings already contain some fungicide, but only in small concentrations because of strict interstate regulations.
Sound Quality Painting
824 90th Dr SE suite B
Lake Stevens WA 98258
(425) 512-7400
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