PAINTS AND STAINS
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 dining room wall. The total thickness of the paint that eventually 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 great deal of that coating of skin. What it can do is determined by a number of factors, like the quality and brand of paint or stain, and how well the walls 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 finish should resist fading, peeling, or yellowing, and also be easy to keep, free from impurities or waxes which 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 surfaces. With their thorough penetration and level of resistance to ultraviolet (UV) light, the stains and finishes on your home's outdoor surfaces should provide a similar high performance.
A Timeline of Paint and Stain
The oldest known paint was employed 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 as the paint on the south side of your property is peeling after only three winters. Here's why: The continuous mild temperature, humidity, and dark interiors of caves are ideal 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 herb dyes to paint images which have lasted a large number of years. The Egyptians used asphalt and pitch to preserve their paintings. The Romans later used white lead pigment, creating 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 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 excellent interior paint. Cassein, the protein in milk, dries very smooth and hard, and can be tinted with other pigments. Like stains, milk paint needs to be coated with a wax or varnish, and it is very durable.
Fashioned from hogs' bristles, badger and goat hair, brushes also evolved 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, are still a preferred brush for oil-based paints.
Pigments originally came from whatever bore a color, from ground up Egyptian mummies to street dirt. Most mineral or inorganic pigments originated from rust, potassium, sea salt, sulphur, alum (aluminum), and gypsum, amongst 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 minimal revisions. However, the colder climates of northern Europe have brought about the need for more durable paint, and in the 1500s the Dutch designer 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 hazardous. Paints and varnishes were usually combined on site, where a ground pigment was blended with lead, oil, and solvents over sustained high temperature. The maladies that arose from toxic exposure were common among painters at least before late 1800s, when paint companies commenced to batch ready mix coatings. While exposure to toxins given off through 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 discover a alternative to 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 attractiveness as a safe, quality alternative 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 every 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 chemical substances, or VOCs, found in standard paint and stains. Harmful and flammable, VOCs evaporate as a coating's solvent dries. They could be inhaled or consumed through your skin, and create ozone pollution when exposed to sunlight.
THE MAKE UP OF PAINT AND STAINS Paints and stains contain four basic types of materials: solvents, binders, pigments, and additives.
Solvents and Binders
Solvents are the vehicle or medium, for the substances 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 between 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 cost 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, enabling 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 higher 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 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 industrial use and a urethane modified alkyd for home use. Urethane boosts longevity.
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; Paint and Stain
Pigments are the costliest ingredient in paint. In addition to providing color, pigments also impact paint's hiding power - its potential to cover an identical color with as few coats as you can. Titanium dioxide is the principal the 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 easier.
Additives; Paint and Stain
Additives regulate how well a paint contacts, or wets, the surface area. 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 potential to flow and level; they go on smoother than latex and dry more slowly, so brush streaks 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 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 induced when the soap wetting agent rises to the surface 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 let it to settle for a couple of hours. That is definitely no longer the case with better paints, that can be opened up and used right from the shaker without threat 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, believe it or not, antifreeze, some latexes can be employed in the same temperature range, and even lower. Some outside latexes can be securely 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 be applied in lower temperature ranges. 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 off. UV blockers in paint may contain finely ground metals and ground glass which is currently being added for increased reflection of natural sunlight.
If you stay in a region with plenty 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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