PAINTS AND STAINS
Almost every kind of surface, from drywall to concrete, needs protection from the elements. These dangerous elements can range between raging blizzards to innocent looking sunlight on a bath room wall. The full total thickness of the paint that ends up outside of your residence is usually about one tenth the thickness of your own skin, and interior paint is even thinner. We ask a lot of that coating of skin. What it can do will depend on a number of factors, like the quality and type of paint or stain, and exactly how well the areas prepped and painted.
Paint and stain should be durable, resisting fading and abrasion and allowing repeated washings. Interior paint can go on with little spattering. An excellent interior stain or clear coating should resist fading, peeling, or yellowing, and also be easy to maintain, free of impurities or waxes that could collect dirt and grime 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 provides 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 Paint and Stain
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 might be wondering why these cave paintings have lasted a large number of years while the paint on the south part of your house is peeling after only three winters. Here's why: The constant 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 vegetable dyes to paint images which have lasted thousands of years. The Egyptians used asphalt and pitch to preserve their paintings. The Romans later used white lead pigment, making 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 superior varnishes such as, shellac, turpentine, copal, and mastic. The formulas and applications for those varnishes also improved little during the 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 excellent 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 sealed with a wax or varnish, and it is very durable.
Created from hogs' bristles, badger and goat hair, brushes also changed little for many 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 came from anything that bore a color, from ground up Egyptian mummies to pasture mud. Most mineral or inorganic pigments came from rust, potassium, sea salt, sulphur, alum (aluminum), and gypsum, amongst others. Some extravagant works incorporated treasured stones such as lapis lazuli. A huge selection of organic and natural pigments from plants, insects, and animals comprised 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 necessity for more lasting paint, and in the 1500s the Dutch artist Jan van Eyck developed oil-based paint.
Starting in 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, in which a ground pigment was blended with lead, oil, and solvents over sustained high heating. The maladies that arose from harmful exposure were common amongst painters at least before late 1800s, when paint companies began to batch ready mix coatings. While contact with toxins given off through the mixing process subsided, contact with the harmful materials inherent in paints and stains didn't change much before 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.
Enhancements 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 altered from simple "whitewashes" to highly advanced coatings that can outlast oil-based products. Both oil-based and latex coatings are emerging each year with well known 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 decrease the volatile organic substances, or VOCs, found in standard paint and stains. Toxic and flammable, VOCs evaporate as a coating's solvent dries. They can be inhaled or consumed through the skin, and create ozone pollution when exposed to sunlight.
PAINTS AND STAINS... THEIR CHEMISTRY Paints and stains contain four basic types of materials: solvents, binders, pigments, and additives.
Solvents and Binders
Solvents will be the vehicle or medium, for the substances in a paint or stain. They regulate how fast a covering 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 depends in large part upon the quality of its binder.
Because water is the vehicle in latex paint, it dries quickly, enabling 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 include a better amount of acrylic resins for better hardness and durability.
Alkyds and oil-based paints are simply the same thing. The word alkyd is derived from "alcid," a blend 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 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 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
Pigments are the costliest element in paint. In addition to providing color, pigments also affect paint's hiding power - its ability to hide a similar color with as few coats as it can be. 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 more easily.
Additives; Stain and Paint
Additives determine 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 more time to level out. That is why oil-based paints have a tendency to run on vertical surfaces more than latexes do.
Latex paint has been trying to catch up with oil-based paint over the years. Today many latexes outperform oil-based paints and primers, because of 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 induced when the soap wetting agent rises to the top 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 had to let it to settle for a couple of hours. This really is no longer the situation with better paints, which is often 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, because it dries slowly and resists freezing, can adhere and dry in temps from 50°F to 120°F. With added coalescents and, believe it or not, antifreeze, some latexes can be applied in the same temp range, and even lower. Some outdoor latexes can be securely applied at heat 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 added to paints and stains to help slow deterioration. Sunlight is responsible for much of the break down of any covering. It fades colors, dries paint, and adds to 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 now being added for even greater reflection of natural sunlight.
If you are in an area with tons of humidity, rainwater, 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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