resins

Resins are a diverse group of organic substances that occur in natural plant exudates or are manufactured synthetically. They are typically viscous liquids or solids that are insoluble in water and resist dissolution, often hardening with exposure to air or heat. The term covers a broad range of materials used as coatings, adhesives, sealants, and casting agents.

Natural resins are produced by many plants, especially conifers, as protective exudates in response to injury or infection. They can harden into solid deposits over time and are often composed of terpenoids and resin acids. Common natural resins include pine resin (colophony or rosin), dammar, copal, lac, and the fossilized resin amber. In botany and commerce, resins are distinguished from gums by their low solubility in water; gums are water-soluble polysaccharide-rich secretions. Rosin, a purified form of pine resin, is widely used in varnishes and as a grip-enhancing additive in violin bows and other applications.

Synthetic resins are polymers produced by chemical synthesis. They include thermosetting resins such as phenolic, urea-formaldehyde, vinyl ester, epoxy, and polyester resins, and thermoplastic resins such as acrylics and certain polyurethanes. Synthetic resins form the basis of many plastics, coatings, adhesives, composites, and casting resins. Across both natural and synthetic varieties, resins are valued for their adhesive strength, film-forming properties, and chemical resistance, but some may present health or environmental concerns if not handled properly.