12 August 2008

Protective Coatings and Paints -04 Coating Composition

Generally, all coating formula consist of three basic categories - solvent, resin, and pigment.
Each of these categories has a special function in the formulation of coatings.
The resin (also called binder) and the solvent form the liquid portion, sometimes called the vehicle. Since the solvent evaporates as a coating cures, it is sometimes called the volatile vehicle, and the resin the nonvolatile vehicle. The resin and pigment which form the solid film after evaporation of the solvent are sometimes called the solid film.

From the past, we could know that the first paints utilized fish or vegetable (e.g., linseed) oils as binders and natural earth pigments. The first solvents were from trees (e.g., turpentine).
Now most resins and solvents are derived from petroleum, and many pigments are derived from organic synthesis or modification of natural minerals. This could answer a question, why coating price is escalate hardly as oil price escalation.

In addition, there are also many additives used in small amounts in coatings to provide some special function.
These include antifoam agents, flattening agents to reduce gloss, mildewcides, adhesion promoters, viscosity modifiers, and ultraviolet stabilizers.[yirf]

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