Cleiuri

Cleiuri is the plural form of the Romanian word clei, meaning glue or adhesive. In general use, cleiuri refer to substances that bind two or more surfaces by forming a bond as they cure or set. Adhesives differ from mechanical fasteners in that they rely on cohesive and adhesive forces at the interface between substrate and adhesive.

Adhesives are classified by origin and setting mechanism. Natural adhesives include animal glue (gelatin), casein glue derived from milk, starch pastes, gum arabic, and dextrin. Synthetic adhesives include polyvinyl acetate (PVA) glue, epoxies, polyurethanes, cyanoacrylates, acrylics, silicones, and phenolic resins. Some systems are moisture- or heat-activated; others cure by chemical reaction as solvents evaporate or monomers polymerize.

Applications and performance: Adhesives are used in woodworking, paper and bookbinding, textiles, packaging, construction, automotive, and electronics. Important properties include bond strength, open time, cure time, viscosity, temperature and moisture resistance, and flexibility. Performance depends on substrate preparation, surface energy, cleanliness, and environmental conditions such as temperature and humidity.

History and safety: Humans have used adhesives since ancient times, evolving from plant starch pastes and animal glues to modern synthetic formulations. Environmental and health considerations focus on volatility, emissions, and recyclability. Many contemporary products are designed to be water-based with lower volatile organic compound (VOC) content, reducing hazards during application.