Paint Systems

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Paint Systems

Paint is a simple mixture of ingredients including pigments, a binder and diluents, or thinner (in a water-based paint it is water; in a solvent-based paint, it is petroleum solvent). Automotive paints utilizing modern paint technology using water-based high solid/low solvent urethane that for environmental reasons produce a much softer and more porous finish than acrylic or oil based high solvent content paint systems. Using permanent pigmentations and colorants specifically designed for automotive applications (containing automotive-grade binders). Albeit a non-toxic (less than 0.01-percent VOC) water-based paint, there are no compatibility issues with major-brand urethane and polyurethane clear coats.

Co lour- the primary pigment is commonly composed of titanium dioxide. The amount of primary pigment impacts greatly on the hiding capabilities of the paint film and UV protection, secondary pigments are pigments such as talc, silica, calcium carbonate, mica, etc., which have little impact on hiding as they are basically used as fillers to help control viscosity, leveling, sheen, etc.

Binder- the binder system for the color and clear coats is formulated from a single component melamine system (PPG Diamond Coat); which holds everything in the paint together (including the pigments) giving the paint its ability to bond, and endure the elements.

Resin- the resin is the film-forming portion of the paint, a synthetic or natural material used as the binder in coatings, can be translucent or transparent, solid or semi-solid. Examples: acrylic, alkyd, copal ester, epoxy, polyurethane, polyvinyl chloride, silicone oil.

Epoxy- by applying an epoxy coat as a sealer, which you can sand if you choose, the epoxy is the only oxygen air tight product used and will seal everything below it, nothing will soak or leech into the 2K primer, and it will also improve adhesion of the base coat and produce a stronger bond. Using the epoxy as a sealer is used mostly with restoration projects and / or by enthusiast detailers that have the time to wait and not rush things

Clear coat- is usually a two-part, high-solid, low-solvent polyurethane or urethane paint used to protect modern water-based paints as they provide a clear, tough and durable protection. Water-basted paints porosity allows the clear to absorb directly into the paint, creating an excellent bond that will not lift or peel (providing the paint has been applied properly)

Polyurethane-a tough, rubber-like elastomer based on the condensation of organic isocyanates with resins containing hydroxyl groups, also referred to as urethane.

Avoid Dimethylsilicone (DMS) aliphatic hydrocarbon solvent based products, as they are migratory, entering into the substrate (resin binder system) and being a solvent they will slowly break down the polymers in the clear coat. In time you'll notice areas where the colour becomes opaque (dull) and you cannot polish the surface to regain its shine. They also release the plastizers from vinyl, rubber and paint; causing them to evaporate out of the substrate, leaving behind a dry inflexible surface.

High or low solids (ratio paint / solvents) - high solids (60/40) that leaves more material (coverage) once paint has cure. Low solids (30/70) means the paint contains more solvents, once they have out-gassed (evaporated) leaves a thinner coat (paint thickness)

Water-based paints are essentially low solids paints (up to 60% solvent), but they are legal because de-ionized water is used as the solvent (water is the most common solvent) as opposed to volatile organic compounds (VOC). In addition to the low solids aspect, waterborne paints have many other properties that help improve the performance and appearance.

(See also Petroleum Distillates, Clear Coat, Paint Curing)

Paint System Thickness- Most modern vehicle paint film systems comprise; Primer coat of 2Mils, Colour coat of 1-2Mils, Clear coat 2-3Mils. Removing more that 0.5 mil 0.0005") of clear coat will cause premature paint film failure. As a point of reference two sheets of Saran wrap placed on top of each other measure 1.5Mil (0.0015") a surface scratch that will `catch' your fingernail is approximately 0.004" deep will usually require wet sanding and refinishing. There comes a point when you must judge wither removing a scratch will compromise the clear coat and if so you’ll have to ‘live’ with the imperfection

Solvents used for the spray painting process:

- Aliphatic hydrocarbons (Mineral Spirits- V M & P,Naphtha)

- Aromatic hydrocarbons (Toluene, Xylene)

- Esters (Ethyl Acetate, Butyl Acetate)

- Ketone (Acetone, Methyl Ethyl Ketone (MEK))

Various combination are used along with other additives (retarders, accelerators, and levellers) to reduce the viscosity of the material to a spray-able consistency and accommodate climatic conditions.

Verious Paint (Coating) Types

Nitrocellulose Lacquer:

This paint had rapid drying and low viscosity properties, applied with a spray gun leaving a hard dry finish in approximately. When polished, and waxed, it far surpassed in durability and appearance the qualities of the Japanese lacquers.

Synthetic Enamel:

Alkyd or synthetic enamels proved to have superior qualities in film strength, adhesion, lustre, flexibility and durability over all previous paints. It dries by solvent evaporation, like the lacquer paints, but the resin remains soft and sticky when no solvents are present. It cures to a hard finish by absorption of oxygen, the curing process can be accelerated by heat. Unlike lacquer, when dry, it doesn't polishing to produce a high gloss finish.

Acrylic Lacquer:

Chemists developed a substitute for nitrocellulose lacquer, using an acrylic resin as a base. The resins used in acrylic lacquer tend to be slightly brittle, with the addittion of a solvent for that softens the resins. Cellulosic resin is derived from cellulose (pure cotton). Acrylic lacquer was used extensively by General Motors (GM).

Acrylic Enamel:

The development of acrylic enamel (harder and more durable) Chemically, it is a cousin to synthetic enamel, but is modified with acrylic resin, which is not soft and sticky with no solvents present. It cures further with air and unlike lacquers, which remain soluble in solvents, the enamel family is insoluble in solvent when cured. An acrylic resin is chemically any polymer whose basic monomers are chemical derivatives of acrylic acid.

Polyurethane Enamel:

Polyurethane enamel was developed to withstand the severe stress of high speed airplane surfaces, which are subject to rapid temperature changes and flexing. This paint was much more durable than the acrylic enamels.

Acrylic Urethane Enamel:

Acrylic urethane enamels were developed to withstand environmental elements, such as acid rain and ultra violet (UV) radiation, it is the most durable paint to date.