Paints are used to ensure protection of the buildings from harmful weather effects, including rain, heat, and winds, and also to improve the surface finish. The useful life of structures is influenced by the application of paints that are available in several varieties of colors and textures.
Paint is in a liquid state and is transformed into a solid layer after being applied on a surface. Paint consists of pigments, suitable additives, and a few binders that are unified by water or oil based solvent. Pigments are coarse solids that are included to improve quality, toughness, texture, and reduce the paint cost. Alternatively, paints may contain dyes as a substitute of pigments.
The pigment and binder ratio in the paint determines the surface shine in the material or component, on which the paint is applied. The purpose of the additives is to improve the paint characteristics, including the resistance to splatter and mildew, convenient cleaning, and protection from ultraviolet rays. The ingredient's characteristics influence the life of the paint. The solvents quantity is high in the cheaper paints.
Some pigments may be toxic, like lead pigments used in lead paint. These pigments have slowly been replaced with the minor toxic materials, like titanium dioxide. The titanium dioxide is normally coated with aluminum or silicon oxides to achieve improved external durability, and enhanced hiding characteristics. These improvements are possible due to the spacing inside the paint film. Pigments are categorized as either synthetic or natural. Synthetics include blanc fix, synthetic silicas, and precipitated calcium carbonate, while the natural pigments include various clays and silicas.
Fillers are a particular category of pigment that is used to compact the paint film, integrate the structure, and augment the paint volume. Fillers normally consist of the inert materials, like lime, clay, etc. Floor paints subjected to scratch may also include delicate quartz sand to serve as filler. However, all paints do not include fillers, though some paints include large quantities of pigment, fillers, and binders.
The binder is normally known as the vehicle. It is the real component of the paint that forms the paint film. It provides adhesion to bind the pigments and influences the essential paint characteristics like gloss, external durability, and toughness. Binders include the natural or synthetic resins like acrylics, polyesters, and epoxy.
Binders are classified according to the system of drying or curing that are oxidative crosslinking, solvent evaporation, coalescence, and catalyzed polymerization. Drying usually implies evaporation of thinner or solvent, while curing involves binder polymerization. The paints may experience either, or both of the processes, in accordance with the requirements of composition and chemistry. Thus, paints may only dry, dry and cure, and also that do not require drying to achieve curing.
Some of the paint categories contain extremely harmful substances that may damage the kidney or liver, or may cause cancer. Even after the paint has been applied and dried, it may release toxic emissions for long durations. These pollutants are produced due to the volatile organic compounds present in the paints. These compounds are a source of the greatest harmful emissions, after the automobiles. Until recently, high intensities of such compounds were used that have been reduced due to the improvement in technology, and general awareness. However, the paints that are nontoxic do not include volatile organic compounds in large quantities, and are therefore safe for the human health.