Sealant Manufacturers produce a wide range of adhesive and sealant formulations. Products vary from high-strength, industrial silicones and adhesives on the one hand to putties, waxes and caulks on the other. In addition, these manufacturers may also produce specialty sealants for special applications such as fire resistance or water proofing. Like adhesives, a sealant’s characteristics depend on the substrate and joint design, performance expectations, production requirements, application environment and economic costs.
A sealant’s physical properties may be characterized by its viscosity, flow ability, paintability or staining resistance and other properties. Chemically, sealants usually contain a base polymer which is modified by various extenders and additives. Some of these additives are designed to improve the surface chemistry of the sealant, while others are intended to modify the performance attributes of the sealant.
The speed at which a sealant cures may be an important factor for some applications. The rate of curing can be improved by the use of catalytic primers or two-component systems. The depth of a sealant’s cure may also be an important consideration. Certain single-component sealants, particularly those based on silicones or urethanes, develop a skin that inhibits the diffusion of atmospheric moisture into the center regions of the sealant bead. This can result in the failure of these sealants to completely cure throughout the joint.
In addition to the above factors, a sealant’s movement capability must be considered when selecting a product for a particular application. The sealant must be able to expand and contract substantially without damage to substrates and joints. Defining this movement capability is often a difficult task because of the many variables involved such as temperature, rates of change in temperature, the nature and configuration of the substrates, and the sealant’s physical properties.
In the case of sealants, manufacturers typically supply these materials in either a liquid or solid form. The latter is typically produced through a process known as sintering whereby the raw material is heated to a point at which it crystallizes into a solid. The liquid form of a sealant is then added to the sintering material and mixed until the desired consistency is achieved. The finished sealant is then packaged for distribution and sale to end users. Some manufacturers may also offer equipment such as a gun and mixer to make it easier for a user to apply the sealant. Other accessories include bond breakers in the form of PVC made nozzles and a spatula to assist with mixing. The latter is especially useful for two-part system sealants which require the base and accelerator to be mixed prior to application. Some manufacturers may also offer specialty nozzles to facilitate the application of the sealant in different positions such as inclined or vertical joints. In addition to these components, some manufacturers may also offer a variety of other accessories and equipment to assist with the production of the finished product such as plasticizers and solvents. These items are typically designed to help ensure that the finished sealant meets specific quality and regulatory requirements for its end use.