During manufacture, along with the pigments that give the wide range of colours, certain additives are included to give paint qualities such as high gloss, or non-drip.
Thixotropic paints are sold as non-drip paints. These are almost jelly-like in the tins, letting you load the brush quicker without drips. In other instances, manufacturers add extenders to fill and strengthen the paint. Cheap, budget paint contains lots of filler. While you get more paint for your money, it often means the paint doesn't cover as well and so you need extra coats. Reinforced emulsion has powdered mica or similar fine aggregate added to it to make a water-thinnable exterior grade emulsion paint that dries with a textured finish.
Paint that is too thick cannot be properly applied and needs to be thinned down before use. Some finishes require special thinners supplied by manufacturers, but most domestic solvent-based (oil) paints can be thinned with white spirit, while emulsions can be thinned with water. Turpentine will thin oil paints but it costs more than white spirit.
The proportion of pigment to resin affects the way in which paint sets. A shiny, gloss paint has approximately equal amounts of resin and pigment. A higher proportion of pigment produces a matt (dull) paint. By adjusting the proportions, it makes it possible to produce eggshell or satin finishes. Matt paints cover well because of their high pigment content, while the resins in gloss paints give them their strength.
Solvent-based (oil) paints are suitable for painting metal. There is a wide range of specialized finishes available: metallic finishes (which contain aluminium, copper, bronze or even gold powders); non-setting security paints used for rainwater and down pipes (the paint remains slippery to prevent intruders scaling walls via external pipes); non-slip paints (ideal for metal spiral staircases and external fire escapes); and radiator enamels (a heat stoving acrylic paint, which can also be used to repaint central heating boiler cabinets, refrigerators, washing machines, and cookers).
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