THE FUNCTION OF STAINS AND PAINTS
Nearly 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 bath room wall. The full total thickness of the paint that eventually ends up on the exterior of your property is usually about one tenth the thickness of your skin, and interior paint is even thinner. We ask a great deal of that covering of skin. What it can do depends upon a number of factors, including the quality and type of paint or stain, and how well the areas prepped and painted.
Paint and stain should be durable, resisting fading and abrasion and allowing repeated washings. Interior paint should go on with little spattering. A quality interior stain or clear coat should resist fading, peeling, or yellowing, and also be easy to keep up, free from impurities or waxes that could collect dirt and make cleaning or recoating difficult. External paints should dry with a toughness that resists deterioration from all sorts of exposure, and an elasticity which allows for constantly expanding and contracting walls. With their deep penetration and level of resistance to ultraviolet (UV) light, the stains and finishes on your home's outside surfaces should give a similar high performance.
Historical Development of Stain and Paint
The oldest known paint was used by the painters of Lascaux, who ground natural pigments with water and a binder that might 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 house is peeling after only three winters. Here's why: The regular mild temperature, humidity, and dark interiors of caves are ideal chemical preservatives. Your home, on the other hand, is exposed to all varieties of weather and conditions.
The Egyptians knew as early as 1000 B.C. that paint could protect as well as decorate. Beeswax, vegetable oils, and gum arabic were warmed and blended with Earth and vegetable dyes to paint images which have lasted thousands of years. The Egyptians used asphalt and pitch to maintain their paintings. The Romans later used white lead pigment, developing a formula that would 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 in the following centuries.
Milk paint goes back to Egyptian times, was widely used 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 smooth and hard, and can be tinted with other pigments. Like stains, milk paint should be covered with a wax or varnish, and is very durable.
Fashioned from hogs' bristles, badger and goat hair, brushes also transformed little for many centuries. Bristles were hand bound, rosined, and greased, then hand laced in to the stock of the brush. Hog's hair brushes, called China bristle brushes, are still a preferred brush for oil-based paints.
Pigments originally came from anything that bore a color, from ground up Egyptian mummies to pasture mud. Most mineral or inorganic pigments originated from rust, potassium, sea salt, sulphur, alum (aluminum), and gypsum, amongst others. Some extravagant works incorporated valuable stones such as lapis lazuli. A huge selection of organic and natural 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 printed in 1773 was reprinted 14 times until 1900, with only minimal revisions. However, the colder climates of northern Europe did bring about the necessity for more durable paint, and in the 1500s the Dutch artist Jan van Eyck developed oil-based paint.
Starting in the Middle Ages lead, arsenic, mercury, and various acids were used as binders and color enhancers. These and other metals made the mixing and painting process unsafe. Paints and varnishes were usually blended on site, in which a ground pigment was blended with lead, oil, and solvents over sustained high temperature. The maladies that arose from harmful exposure were common among painters at least until the late 1800s, when paint companies commenced to batch ready mix coatings. While contact with contaminants given off through the mixing process subsided, contact with the harmful ingredients 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 commenced to synthesize dyes. Today many pigments and dyes are chemically synthesized.
Inventions in the painting industry have extended well beyond pigments. Water-based latexes have gained in popularity as a safe, quality alternative to oil-based paints. Latexes have changed from simple "whitewashes" to highly advanced coatings that can outlast oil-based products. Both oil-based and latex coatings are emerging yearly with notable improvements, like 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 decrease the volatile organic chemical substances, or VOCs, found in standard paint and stains. Dangerous and flammable, VOCs evaporate as a coating's solvent dries. They can be inhaled or soaked up through the skin, and create ozone pollution when exposed to sunlight.
THE MAKE UP OF STAINS AND PAINTS Paints and stains contain four basic types of materials: solvents, binders, pigments, and additives.
Paint and Stain Solvents and Binders
Solvents are the vehicle or medium, for the ingredients in a paint or stain. They regulate how fast a coating dries and exactly how it hardens. Water and alcohol are the primary solvents in latex. Oil-based solvents range from mineral spirits (thinner) to alcohols and xylene, to napthas. The solvent also contains binders, which form the "skin" when the paint dries. Binders give paint adhesion and longevity. The expense of paint depends 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 see when utilizing 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 greater amount of acrylic resins for greater hardness and durability.
Alkyds and oil-based paints are simply the same thing. The term alkyd comes from "alcid," a mixture 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 professional use and a urethane revised 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 stronger, require only water clean-up, have little odor, and are non-flammable. One disadvantage: They swell hardwood grain and require sanding between coats.
Paint and Stain Pigments
Pigments will be the costliest component in paint. In addition to providing color, pigments also influence paint's hiding power - its ability to hide an identical color with as few coats as you possibly can. Titanium dioxide is the primary the most expensive ingredient in pigment. Top quality paints not only have more titanium dioxide, but also more finely ground pigment. Inexpensive paints use coarsely ground pigment, which doesn't bind well and washes off easier.
Additives
Additives regulate how well a paint contacts, or wets, the surface. They also 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 marks have more time to smooth out. That is why oil-based paints have a tendency to drip on vertical surfaces 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 known as 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 caused when the soap wetting agent rises to the surface as it dries. The better the paint, the less pin holing you will have. It used to be that if latex paint was shaken at the paint store you would have to let it to settle for a few hours. It is no longer the case with better paints, that can be opened and used right from the shaker without danger of pin holing.
Coalescents help latex resins bond, especially in colder weather. Oil-based paint, because it dries slowly and resists freezing, can adhere and dry in temperatures from 50°F to 120°F. With added coalescents and, contrary to popular belief, antifreeze, some latexes can be employed in the same temperature range, and even lower. Some outdoor latexes can be safely applied at temps at only 35°F. Companies including Pratt & Lambert, Pittsburgh Paint, and Sherwin Williams have removed the surfactants to help their latex paints go on in lower temperatures. As the wetting agents have been removed, the latex dries faster.
UV blocking additives have been put into paints and stains to help slow the aging process. Sunlight is accountable for a lot of the break down of any covering. It fades colors, dries paint, and increases the expansion and contraction process which makes paint crack and peel. 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 stay in a region with a lot of humidity, rainfall, and insects, you may want 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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