THE PURPOSE OF PAINTS AND STAINS
Nearly every kind of surface, from drywall to concrete, needs protection from the elements. These hazardous 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 property is usually about one tenth the thickness of your skin, and interior paint is even thinner. We ask a great deal of that layer of skin. What it can do depends on a number of factors, like 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. An excellent interior stain or clear coating should resist fading, peeling, or yellowing, and also be easy to keep up, free of impurities or waxes that 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 that allows for constantly expanding and contracting areas. With their deep penetration and level of resistance to ultraviolet (UV) light, the stains and finishes on your home's exterior should provide a similar high performance.
The History 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 may have been honey, starch, or gum. You might be wondering why these cave paintings have lasted a large number of years as the paint on the south part of your home 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 subjected to a myriad 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 mixed with Earth and flower 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, making a formula that could 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 superior varnishes such as, shellac, turpentine, copal, and mastic. The formulas and applications for those varnishes also evolved 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 has been revived as an alternative interior paint. Cassein, the protein in milk, dries very flat and hard, and can be tinted with other pigments. Like stains, milk paint must be covered with a wax or varnish, and is very durable.
Created from hogs' bristles, badger and goat hair, brushes also transformed little for several 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, remain a preferred brush for oil-based paints.
Pigments originally originated from whatever bore a color, from ground up Egyptian mummies to road dirt and grime. Most mineral or inorganic pigments originated from rust, potassium, sea salt, sulphur, alum (aluminum), and gypsum, among others. Some extravagant projects incorporated treasured 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 publicized in 1773 was reprinted 14 times until 1900, with only modest revisions. However, the colder climates of northern Europe have brought about the need for more lasting paint, and in the 1500s the Dutch artist Jan van Eyck developed oil-based paint.
Starting around 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 hazardous. Paints and varnishes were usually combined on site, in which a ground pigment was blended with lead, oil, and solvents over sustained high heat. The maladies that arose from harmful exposure were common amongst painters at least before late 1800s, when paint companies started out to batch ready mixed coatings. While exposure to toxins given off during the mixing process subsided, exposure to the harmful ingredients 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 find a alternative to the natural pigments and dyes that originated from Germany. They started out 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 acceptance 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 annually 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 category of paints and stains known as "water borne." Created by the need to comply with stricter regulations, water borne coatings decrease 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 absorbed through your skin, and create ozone pollution when subjected to sunlight.
STAINS AND PAINTS 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 ingredients 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 resilience. The cost of paint is dependent 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 see when 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 increased 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 combination 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 high performance combinations such as two part polyester-epoxy for professional use and a urethane revised alkyd for home use. Urethane boosts durability.
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 real wood grain and require sanding between coats.
Pigments
Pigments will be the costliest ingredient in paint. In addition to providing color, pigments also influence paint's hiding power - its capability to hide an identical color with as few coats as it can be. Titanium dioxide is the principal 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.
Stain and Paint 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's why oil-based paints tend 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 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 would have to let it to settle for a few hours. This is certainly no longer the situation 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 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 outside latexes can be properly applied at temperatures 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 temperature. As the wetting agents have been removed, the latex dries faster.
UV blocking chemicals have been added to 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 adds to 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 the sun's rays.
If you stay in an area with lots of humidity, rain, 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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