What Is Epoxy



If you are considering the investment of a concrete coating system for your garage, basement, patio, or warehouse it’s important to understand how products differ and why.

Garage Store and its staff have been in the concrete coating business for years and have worked with multiple formulators and products. The bottom line is all products are not created equal and there are a lot of buzz words and terminology that every consumer should know and understand. We have composed a brief summary of products and terms to help you select the best concrete coating system for your application.

The term “epoxy” is a catch all term used to cover coatings that use a two component system. As defined from this reference:

Epoxy is a copolymer; a mixture of two different chemicals. These are referred to as the "resin" and the "hardener". The resin consists of monomers or short chain polymers with an epoxide group at either end.


tr.v. ep•ox•ied, ep•ox•y•ing, ep•ox•ies: "fasten together with epoxy"

The term epoxy is used loosely in the coating industry and with formulators, installers and consumers because, generally, an epoxy has greater adhesion and wear properties than paint. However, just as there are different qualities of paints, there are different qualities of epoxies. More specifically the quality of the epoxy is related to the application and purpose of the epoxy.

For example:
1. An epoxy for coating concrete in a zero sunlight exposure warehouse is different from an epoxy
used to coat a concrete patio in direct sunlight.
2. An epoxy used to fill a control joint is different than an epoxy to repair concrete.
3. An epoxy used as a basecoat or primer is different than an epoxy used as a topcoat.

Here’s a brief review of terms you have heard or read about and what they really mean:

Epoxies are thermosetting products known for excellent substrate (concrete) adhesion, mechanical properties, and chemical resistance.

Epoxy systems are made up of two components:
1. an epoxy resin
2. a curing agent (also know as a catalyst or hardener)

The resin and curing agent are packaged separately and mixed just prior to use. When epoxy systems are used (mixed), single molecules (monomers) of the epoxy resin and the curing agent combine to form long chain molecules (polymers). As the epoxy “cures” it becomes a solid polymer system with superior characteristics of hardness and chemical resistance. These characteristics are dependent on the type of resin, curing agents, solvents, and fillers used.

While there are only a few resins that are suitable for working with concrete applications, there are many curing agents. Therefore, epoxies can be formulated to have a variety of physical properties which makes it difficult for the person installing to generalize them as epoxies. Now you can understand the differences and why all epoxies are not created equal.

Epoxy for concrete coating come in three formulations:
1. solvent based
2. water based
3. 100% solid

100% solids epoxies are the most popular form and most often used by Garage Store because we get the best results. The percent solids describe the amount of solvent used. For example, a 100% solids epoxy has no or very little solvents. A 70% solids epoxy may have 20% solvents and 10% fillers and/or bonding additives. As a result, the benefit 100% solids epoxy offers an almost odorless installation which is great for the residential market and the environment.


The chemistry of polyaspartic coatings was first introduced in the early 1990s. The name polyaspartic has recently become popular or the buzz word among formulators in the industry due to the need to differentiate it from polyureas and polyurethanes. By definition, a polyaspartic is an aliphatic polyurea because it is the reaction of an aliphatic polyisocyanate (curing agent) with a polyaspartic ester (resin), which is an aliphatic diamine. However, polyaspartic coatings are very different in both application and coating performance properties from conventional polyureas. For example, polyaspartics allow the formulator to control the rate of reaction and cure; consequently the amount of usable time for the two-component mixture can range from five minutes to three hours.

More recent developments in polyaspartic coating technology and environmental regulations have concentrated on achieving low or near-zero volatile organic carbon (VOC) coatings where the polyaspartic ester is the main component of the co-reactant for reaction with a polyisocyanate.
The unique and adjustable reactivity of the polyaspartic esters allows for the design of fast-curing coatings tailored to the needs of the application. The fast curing feature of these coatings can provide significant, money-saving productivity improvements, along with high-build, low-temperature curing, and abrasion and corrosion resistance.

Build capability – how thick the coating actually is which results in longer wear life.

Polyaspartics generally have a very low viscosity (equivalent to water) which gives it outstanding wetting ability to apply a high build in one coat, UV stability, and excellent chemical and abrasion resistance thus providing some of the best properties.


Now you understand why all epoxies are not created equal. I recommend you compare apples to apples and ask your installer or salesperson for ASTM specification on the product you want installed. The only way to confirm or assure you are getting what you are paying for is to compare specs of the final cured product. Over the years, we have seen a lot of company’s say they offer the best products but can’t support or defend their products with specifications. Additionally, be carful of warranty disclaimers, ask them to read the fine print and explain it to you in a way that you understand.

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