Liquid sealant is a broad term for a number of generally unrelated products except that all share one specific trait. A liquid sealant is defined as any product that starts out as a liquid but hardens to a protective seal when dry. Acrylic, polyurethane, urethane, Teflon® and silicon-based caulks are common types of liquid sealants used in construction. These sealants are used for a variety of purposes, including crack repair, joint and seam filling, water sealing of wood and concrete, as well as for joining pipes and fixtures. Nail polish, denture sealers, and a variety of other household bonding products can all carry the designation of liquid sealant. In addition, a new type of all-purpose liquid sealant, based on glass, is also available.
Selecting the correct liquid sealant for a construction project — such as choosing silicon over acrylic to seal a bathtub's seams — is based on joint design, physical and chemical properties, durability, and application properties. Joint design refers to how the sealant matches the need of the joint and if the sealant maintains adhesion and cohesion under expected movement parameters of the joint. The physical and chemical properties influence the hardness of a sealant and determine whether it is clear or colored to match a surface. A liquid sealant's durability relates to how the sealant reacts to its environment — whether it is waterproof, if it deters mold growth, and if it can be used in ultraviolet light or under extreme temperatures. Application, or installation, properties include whether the sealant is pourable or requires a caulk gun, how long the product needs to dry, and at what temperature range the application process can be made.
The German-based Nanopool® company began widespread marketing of a new form of liquid sealant based on quartz glass. This liquid glass seal is purported by its creator to be usable on almost any type of surface, from clothes to medical scalpels. The sealant is reported to create a microscopic protective seal — 500 times smaller than a human hair — of biodegradable glass that guards against stains, water, ultraviolet light, dirt, bacteria, and mold. The sealant can also be applied to seeds and vines to protect against fungus and mildew and to wood to guard against termites.
A number of household and personal care products are also marketed as liquid sealants. Some of the more common of these include denture adhesives, nail polish, and tooth sealant. Denture adhesives bond dentures to the gums in the mouth. Nail polish is used to color and protect finger and toe nails from chipping. Tooth surface seals are implemented in protecting against tooth decay.