Epoxy 101: What is Epoxy?

What is Epoxy? Definition and Synonyms

Ask the question “What is epoxy?” and you will find multiple definitions from a variety of sources. Epoxy is so widely used by many industries, that its definition varies slightly based on the application.

Definition of Epoxy:

  • Epoxy is a class of resin derived by polymerization from epoxides. Epoxies are used chiefly in adhesives and coatings.
  • Epoxy is a thermosetting resin capable of forming tightly linked cross-polymer structures.
  • Epoxy is characterized by toughness and strong adhesion, especially when used for floor coatings.

Epoxy Synonyms:

epoxy resin, epoxy polymers, epoxy coating, epoxy paint

What is an Epoxy?

Epoxies are polymer materials that begin as liquids and are chemically changed into a solid. An epoxy based polymer is mechanically strong, chemically resistant to degradation from chemical elements in the solid form, and highly adhesive during conversion from liquid to solid. There are a wide range of basic epoxy chemicals from which an epoxy coating system can be formulated.

What are epoxies? Physically epoxy coating systems contain two components, resins and hardeners. The resin component is usually light, sometimes almost clear colored, and almost odor free. Hardeners are usually dark and have a slight odor. When these two components are mixed, they will chemically bond together, and once the chemical reaction has finished, they will form a strong and rigid plastic material.

This Epoxy 101 guide answers the question: What is Epoxy? For additional information on using epoxies, see: Working with Epoxy Coatings

Why use an Epoxy?

Epoxy coatings are used because of their outstanding chemical resistance, durability, low porosity and strong bond strength. Epoxy coatings can be formulated to be field applied, brushed-on, rolled-on, or troweled-on.

Epoxies are known for their excellent adhesion, chemical and heat resistance, good-to-excellent mechanical properties, and very good electrical insulating properties.

What are epoxies used for? Applications of epoxy based materials are extensive and include: coatings (i.e. epoxy floor coatings or anti-corrosive coatings), adhesives and composite materials like carbon fiber and glass-reinforced plastic (although polyester, vinyl ester, and other thermosetting resins are also used for glass-reinforced plastic). There are even special epoxy coating formulations that offer increased chemical resistance, increased temperature resistance, and the ability to be applied underwater.

What is Epoxy? Epoxies Make Great Floor Coatings:

While epoxy floors are very common, for serious and demanding applications the epoxy is either mixed with, or applied under and above, quartz (sand) or aluminum oxide grains. Either way, the result is really a quartz or aluminum oxide floor, held in place with the epoxy. The quartz, and even better the aluminum oxide, is much more durable and wear resistant than the epoxy alone.

Adhesion of Underwater Applied Epoxies:

Underwater epoxies generally have good-to-excellent adhesion to most submerged surfaces (i.e. emergency boat hull repair); however, steel surfaces in saltwater environments can be a problem. Such surfaces are often protected by a cathodic protection system. These systems use electrical current to suppress corrosion. Dissimilar metals in saltwater also form tiny electrical cells. Because epoxy bonding is due to molecular attraction of charged particles, existing electrical charges, known or unknown, can interfere or disrupt epoxy bonding. It is best to test underwater coatings for possible cathodic adhesion problems if used in marine settings on steel surfaces.

How Much Does Epoxy Cost?

The best epoxies are expensive, especially industrial strength epoxies. If you find inexpensive industrial epoxies on the market, chances are they may have been “watered down” with thinners or low quality solvents. These diluted cheap epoxies are lower performing epoxies, and will not stand up to repeated use as well as true industrial strength epoxies. Businesses looking for ‘floor epoxies’ are advised to invest in an unaltered industrial strength floor coating and avoid diluted down epoxies. As the old saying goes, ‘you get what you pay for’.

How to Identify Cheap Epoxy:

Cheap epoxies may contain large amounts of a non-solvent thinner called nonylphenol. Nonylphenol is an inexpensive chemical that is often added to epoxies. Check your epoxy’s MSDS for any mentions of nonylphenol.

A cheap epoxy may also require hazmat shipping. Generally, higher quality resin systems, such as Novolac epoxies, can be shipped non-hazmat. The exceptions are special high temperature and/or more UV resistant epoxies, which often require hazmat shipping.

Cheap epoxies also tend to have a required ‘induction time’, where the mixture must sit to ‘self-cook’ for several minutes after mixing the two components are mixed together. Crystallization of either the resin or the hardener, like crystallized honey, is another common trait of cheap epoxies.

Most epoxies tend to ‘blush’ to some degree as they cure. Blushing is the formation of a waxy coating on the surface of the curing epoxy due to moisture in the air. High quality epoxies will have minimal blushing

The Problem with Solvents in Cheap Epoxies:

Adding a bit of solvent to a solvent based or solvent-free epoxy is something that most manufacturers would not officially approve of and something that might not work with all epoxies.

Most States and the EPA have regulations regarding the acceptable levels of these carcinogenic agents allowed in products due to health and environmental concerns. Not only are they a health hazardous substance, they are one of the primary causes of coating failures. As the solvents evaporate in to the air and water, the coating becomes thinner and holes are created in coating’s structure, causing permeability problems. This process continues long after the original curing process. The results are a failing coating system that will allow the penetration of harmful chemicals to undermine the coating and damage the structural base metal or concrete.

Less Expensive Polyester Resins vs. Epoxy Resins

Polyester resins, or fiberglass resins, cost far less than epoxy resins. Polyester resins are much more porous than epoxy resins, have stronger fumes, and only stick well to themselves. Unlike polyester resins, solvent-free epoxies can be applied to foam without dissolving it.

The Novolac Epoxy Advantage:

Novolac is the cutting edge in epoxy technology:

  • Environmentally Safe (Hybrid NOVOLAC systems are 100% solids, with no solvents, and no volatile compounds)
  • Superior Bonding (Novolac epoxies bond both mechanically and chemically to metal and concrete)
  • Higher Chemical Resistance (A high chemical resistance, with ability to withstands up to 98% sulfuric acid)
  • Higher Temperature (Novolac epoxies can be engineered to withstand temperatures exceeding 400 °F)
  • Superior Abrasion Resistant (Novolac epoxies undergo high impact texting for abrasion and chemical resistance)
  • Reinforcing Kevlar™ Fibers (Novolac epoxies are Kevlar reinforced, increasing wear resistance and reducing the possibility for cracking or chipping.)

Thanks

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