Epoxy glues have been developed for a large number of applications. Manufacturers use a resin with a hardener to make the glue. These glues are usually very heat, water and chemical resistant once dry. Some glues dry very quickly while others dry slowly.
Epoxy is a structural adhesive that bonds items together while improving the strength of the overall product rather than the bond being a weak portion of the product. Specific epoxy glue has been developed for the construction of very large items such as airplanes, while another epoxy might be used for adhesion of craft items.
Most epoxy glue is sold in two parts wherein the resin must be mixed with the hardener and applied to the items to be bonded together. The amount of resin and hardener to be used varies based upon the application. Epoxy applied to two dry items usually dries at room temperature without the need for any other fixative. Some two-part epoxies dry very quickly and should only be mixed in small amounts to avoid waste.
Certain two-part epoxies are sold in one container that dispenses an equal amount of resin and hardener at the same time. These amounts must then be mixed before they are applied to the item needing the epoxy glue. The benefit of these types of dispensers is that there is no need for separate measurement of the resin and hardener. These types of epoxy glue dispensers are best for use on small projects, as they do not contain much product within the dispenser itself.
Epoxy glue is also used in dental work and other wet settings. Epoxy glue applied in a wet setting usually requires some other type of fixative to help the epoxy dry. For example, some types of epoxy glue are developed to be used with an ultraviolet light to cure the epoxy. Once cured, the epoxy is almost indestructible.
In certain applications, the resin is combined with a more flexible hardener, which gives the bond some flexibility for movement within the bonded product. The amount of available movement varies based upon the intended application. For example, epoxy developed for use on a PVC pipe alone requires very little flexibility whereas an epoxy glue that is used for bonding a PVC pipe to metal needs more flexibility due to the different substrates being bonded. Some epoxies are developed as a gel so they may be applied in a vertical or overhead setting.