FEATURES OF STAINS AND PAINTS
Nearly every kind of surface, from drywall to concrete, needs protection from the elements. These dangerous elements can range from raging blizzards to innocent looking sunlight on a bed room wall. The full total thickness of the paint that eventually ends up on the exterior of your house is usually about one tenth the thickness of your skin, and interior paint is even thinner. We ask a lot of that layer of skin. What it can do is determined by a number of factors, including the quality and brand of paint or stain, and exactly 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 reduced spattering. An excellent interior stain or clear coat should resist fading, peeling, or yellowing, and also be easy to maintain, free of impurities or waxes which could collect dirty residue and make cleaning or recoating difficult. Outside paints should dry with a toughness that resists deterioration from all sorts of exposure, and an elasticity which allows for constantly expanding and contracting surfaces. With their thorough penetration and resistance to ultraviolet (UV) light, the stains and finishes on your home's outside surfaces should provide a similar high performance.
The Evolution of Stain and Paint
The oldest known paint was utilized by the painters of Lascaux, who ground natural pigments with water and a binder that might have been honey, starch, or gum. You might be wondering why these cave paintings have lasted thousands of years as the paint on the south part of your house is peeling after only three winters. Here's why: The frequent mild temperature, humidity, and dark interiors of caves are ideal chemical preservatives. Your house, on the other hand, is exposed to all sorts 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 preserve 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 also to preserve wood. The Chinese used gums and resins to make complex varnishes such as, shellac, turpentine, copal, and mastic. The formulas and applications for those varnishes also improved little in the following centuries.
Milk paint dates 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 has been 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 has to be sealed with a wax or varnish, and 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, are still a preferred brush for oil-based paints.
Pigments originally originated from anything that bore a color, from ground up Egyptian mummies to street mud. Most mineral or inorganic pigments originated from rust, potassium, sea salt, sulphur, alum (aluminum), and gypsum, along with others. Some extravagant projects incorporated treasured stones such as lapis lazuli. A huge selection 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 printed in 1773 was reprinted 14 times until 1900, with only minor revisions. However, the colder climates of northern Europe did bring about the need 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 harmful. Paints and varnishes were usually combined on site, where a ground pigment was mixed with lead, oil, and solvents over sustained high heating. The maladies that arose from harmful exposure were common among painters at least until the late 1800s, when paint companies started to batch ready mixed coatings. While exposure to poisons 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 discover a replacement for the natural pigments and dyes that originated from Germany. They started to synthesize dyes. Today many pigments and dyes are chemically synthesized.
Innovations in the painting industry have extended well beyond pigments. Water-based latexes have gained in reputation as a safe, quality option to oil-based paints. Latexes have transformed from simple "whitewashes" to highly advanced coatings that can outlast oil-based products. Both oil-based and latex coatings are emerging each year with notable improvements, including the ground metal or glass that's now added to reflect harming UV light.
A milestone in the evolution of coatings occurred in the very early 1990s with the introduction of a fresh class of paints and stains known as "water borne." Created by the need to adhere to stricter regulations, water borne coatings decrease the volatile organic compounds, or VOCs, found in standard paint and stains. Toxic and flammable, VOCs evaporate as a coating's solvent dries. They could be inhaled or absorbed through your skin, and create ozone pollution when exposed to sunlight.
STAINS AND PAINTS CHEMISTRY Paints and stains contain four basic types of ingredients: solvents, binders, pigments, and additives.
Paint and Stain Solvents and Binders
Solvents are the vehicle or medium, for the materials in a paint or stain. They regulate how fast a coating dries and 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 includes binders, which form the "skin" when the paint dries. Binders give paint adhesion and durability. The expense of paint is dependent in large part upon the grade 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 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 greater amount of acrylic resins for higher hardness and durability.
Alkyds and oil-based paints are basically the same thing. The term alkyd comes from "alcid," a combo of alcohol and acid that acts as the drying agent. Both have the same binders, which may include linseed, soy, or Tung oils. Oil based and alkyd enamels may contain polyurethanes and epoxies for extra hardness. Alkyd paints come in high performance combinations such as two part polyester-epoxy for commercial use and a urethane modified alkyd for home use. Urethane boosts toughness.
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 raise real wood grain and require sanding between coats.
Pigments; Stain and Paint
Pigments are the costliest ingredient in paint. In addition to providing color, pigments also influence paint's hiding power - its ability to protect an identical color with as few coats as you can. 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 area. 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 potential to flow and level; they go on smoother than latex and dry more slowly, so brush marks have a chance to smooth out. That's why oil-based paints have a tendency to drip on vertical areas more than latexes do.
Latex paint has been trying to catch up with oil-based paint over time. Today many latexes outperform oil-based paints and primers, because of 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 caused 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 had to let it to settle for a couple of hours. This really is no longer the case with better paints, which can be opened and used right out of the shaker without threat of pin holing.
Coalescents help latex resins bond, especially in colder weather. Oil-based paint, since it dries slowly and resists freezing, can adhere and dry in temperature from 50°F to 120°F. With added coalescents and, contrary to popular belief, antifreeze, some latexes can be applied in the same temperature range, and even lower. Some outside latexes can be properly applied at conditions as low as 35°F. Companies including Pratt & Lambert, Pittsburgh Paint, and Sherwin Williams have removed the surfactants to help their latex paints go on in lower heat. 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 breakdown of any covering. It fades colors, dries paint, and adds to the expansion and contraction process that makes paint crack and peel. UV blockers in paint may consist of finely ground metals and ground glass which is currently being added for increased reflection of the sun's rays.
If you reside in an area with tons 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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