Resin See also: Amber Any of a class of amorphous solids or semisolids (see States Of Matter). Natural resins occur as plant exudations (e.g., of pines and firs), and are also obtained from certain scale insects. They are typically yellow to brown in Color, tasteless, and translucent or transparent. Oleoresins contain essential Oils and are often sticky or Plastic; other resins are exceedingly hard, brittle, and resistant to most solvents. Resins are used in Varnish, Shellac, and lacquer and in medicine. Synthetic resins, e.g., Bakelite, are widely used in making plastics.