— Clarify application scenarios: Select proper types based on indoor/outdoor surroundings, humidity, temperature, base materials and sealing demands. Neutral silicone sealant fits outdoor doors and windows; polyurethane sealant suits concrete expansion joints; polysulfide sealant applies to underwater environments.

— Inspect product quality: Opt for goods from formal manufacturers. Check test reports and shelf life, avoid unqualified products. Qualified sealant features uniform texture without lumps or peculiar smell, and forms smooth bubble-free surface after curing.

— Check performance parameters: Focus on bonding strength, elongation rate, temperature resistance and curing time. Outdoor applications require products with elongation rate no less than 300% and UV resistance.

— Distinguish functional differences: Sealants are divided into sealing type and bonding-sealing type. Choose the former only for gap filling, and the latter for dual bonding and sealing effect. Special fireproof and mildew-proof sealants are available for specific demands.