Epoxy Adhesives For Strength and Durability
What's the scoop on epoxy?
Consumer epoxy adhesives are two-part plastic resin glues. The two parts... resin and hardener... chemically react when mixed and produce a strong adhesive bond to virtually any clean surface. They generally have a long shelf life since they don't set in the tube (unless you leave the cap off). There are also one-part epoxies that are designed for professional use. Heat instead of a chemical hardener is used to start the reaction that sets the epoxy.
Some epoxies not only produce a strong bond but also set quickly...some in as little as five minutes! However, setting time is very dependent on temperature. A "5 Minute" epoxy can become an hour epoxy below 60 degrees F... so read that label!
Epoxies set hard and will fill gaps, adding strength and stiffness to the materials glued. This is great for some materials, but not so good for others. Non-rigid materials such as fabrics and flexible plastics are better glued with GOOP (see next article) caulks and PVC adhesives. Though epoxies are recommended for wood by their manufacturers, wood glues are in my opinion a better selection unless quick setting is absolutely necessary. Epoxy makes a great secondary adhesive on most materials, including wood. For more on primary and secondary adhesives see the Famous Glue Trick at the end of this article!
Because epoxies set with adhesive strength and rigidity, thick formulations are employed as wood and metal fillers for use under the most severe circumstances. For example, epoxies are used to set bolts in concrete floors to stabilize heavy vibrating machinery and for some types of plumbing repairs. Various metal additives are used in some epoxies for material compatibility... for example steel, aluminum, bronze and titanium are added for repairs to those metals. This is necessary because different metals can react with each other over time, damaging the repair.
Other epoxy fillers are also used to restore rotten wood in homes and other wooden structures. Conserv Epoxy at http://www.conservepoxy.com manufactures specialty epoxies that not only repair rot but actually restore the strength to rotted wood. Their sturdy formulations have saved homeowners thousands of dollars in renovation projects where structural beams and supports have been attacked by rot, carpenter ants and termites!
Other manufacturers of widely-available consumer epoxies are Devcon and the Protective Coating Company adhesives.