TYPES OF PAINT
- Alkyd Paints
- Latex Paints
Vinyl Acrylic Latex
- Epoxy Ester Coatings
- Catalyzed Epoxy Coatings
- Polyurethane Finishes
Catalyzed Aliphatic Polyurethanes
Alkyds are extremely versatile synthetic resins that dry faster and are much harder than ordinary oils such as linseed oil. They are made by combining synthetic materials with various vegetable oils (linseed, soya, tung, etc.) to produce clear resins. Drying results from both the evaporation of the solvent and from oxidation of the alkyd. Mineral Spirits is used as the solvent and thinner for most alkyd paints.
Alkyd paints are generally available in a wide range of sheens for interior or exterior architectural and industrial plants. They have gradually replaced oil base paints because of their faster dry, and superior gloss and color retention. Like oil base paints, alkyds will tend to yellow or darken with age in interior environments, although not as severely. They should not be used directly on masonry or other alkaline surfaces such as plaster, galvanized metal or brick.
Latex binders are synthetic materials that can be varied in flexibility, hardness, gloss level, color retention, etc. All latex paints are water thinned. Drying results from coalescence of latex particles as the water evaporates from the film.
Latex paints have become extremely popular for painting both interior and exterior surfaces. Their advantages versus alkyd or oil paints include better color and gloss retention, VOC compliance, lower odor, faster dry and recoating, easier clean-up, more blister and peel resistance and better alkali resistance. The main limitations of latex paints are they should be applied above 50 F. and they must be kept from freezing.
The two most common types of latex paints are:
Vinyl Acrylic Latex (PVA) – Used mostly in interior wall paints and trim enamels. Provides excellent washability, yellowing resistance, ease of applications and self-sealing properties. Fast dry allows applications of two coats in one day. Does not raise the “grain” of drywall fibers. Limitations are inferior wet adhesion, water resistance, alkali resistance and gloss and color retention versus acrylic latexes. Acrylic Latex – Used mostly in interior trim enamel and exterior house paint on wood or masonry. superior to alkyd, oil, and vinyl acrylic latex paints in color and gloss retention, alkali resistance, and blister resistance. Ideal for new work or repaint work. Acrylic latex paints are recommended for the best performance.
Epoxy Ester Coatings
Epoxy esters are epoxies modified with oil to produce a coating which will dry by oxidation. They are single package paints that do not require the use of a catalyst or converter for curing. Epoxy esters possess better chemical resistance, especially to alkalies, than oil or alkyd paints.
They can be used on areas where there is some splash and spillage of chemicals. Epoxy esters are not as hard or chemical resistant as catalyzed epoxies, but offer a good compromise in performance between epoxies and alkyd paint. They will lose gloss and chalk in exterior areas, but only appearance not performance is affected.
Catalyzed Epoxy Coatings
These are two package coatings produced by mixing an epoxy base portion with a hardener or converter portion. The converter reacts chemically to produce an extremely hard, tough, film. When mixed an epoxy coating has a limited pot life varying generally from about four to sixteen hours.
Catalyzed epoxy coatings provide outstanding chemical resistance making them ideal for use in industrial areas. Commonly used as floor coatings due to their excellent abrasion resistance. Also used as glazed wall tile-like finishes due to their outstanding stain resistance, hardness and ease of cleaning. Most epoxies will tend to chalk rapidly on exterior surfaces and yellow in interior areas, but remain durable.
Oil-Modified Urethanes – This type consists of a blend of urethanes, drying oils and alkyds. They dry by evaporation of solvent and oxidation of the oil. They are one package, air dry types. They feature outstanding abrasion resistance on wood floors, furniture, paneling, cabinets, etc. Catalyzed Aliphatic Polyurethanes – Two component type having outstanding gloss and color retention, abrasion resistance, and chemical resistance. They cure by the Isocyanate component reacting with a polyo component (acrylic or polyester). Like catalyzed epoxies, the mixture has limited pot life.