What a Difference the Topcoat Makes.
It is hard to figure out exactly what is the best product to use for each project when there are so many options available. While the finished products may look similar and the aggregates used can make the initial colors and textures identical; the materials used in the system are very different. For a designer or architect, it is important to choose the best product for the customers use and the environment. When resinous flooring first came to the United States, there were few choices, but today there are many choices to provide the best produce for each and every project. I will try to simplify the process and help clarify the selection process.
First, it is important to understand the major material options. There are four major options for use in most projects, and they are available from most of the more mainstream manufacturers. Epoxy, Polyurethane, Polyaspartic, and MMA are all used as topcoats and complete systems in many resinous flooring projects. All of these products are transparent resins that are made up of multiple components and cure to a clear finish. All of these products except for MMA will look very similar directly after installation unless additives are added for texture. The danger of not understanding these products is that most people cannot tell the difference between them until the floors go into service, and by then, it is too late.
Chemists have spent years developing resins that will work well in different environments. While epoxies of the last century worked well, there were weaknesses that needed to be resolved. Below, I will try to outline the best qualities of each type of material. It is important to understand that the application of each product has an impact on the finished product and some of the products listed are more difficult to install than others.
Epoxy is the grandfather of the others in the resinous flooring industry. It is strong, easy to use and still very relevant. Epoxy has been used for flooring for many years and is still used on many projects. While many systems are entirely made up of Epoxy, they are also used as primers and base coats for other types of systems. Epoxy's bond well to concrete and to themselves; they work well with sand and aggregates and rarely cause problems with out-gassing or fish-eyes. Think of Epoxy as a great building block or foundation to many other flooring systems. While epoxy has great qualities, it also has weaknesses. Epoxy turns amber over time, and even though scientists have improved its light stability, it is still not as light stable as its newer cousins. Epoxy is also not very resistant to heat; it is however chemical resistant, especially in its Novalac form, but much less light stable.
PolyUrethane is the next step up in Resins; it is very clear and light stable. Urethane's first gained popularity in the flooring industry as topcoats on epoxy systems in airplane hangers and automobile dealerships. First generations urethane's contained solvents and would not meet today's VOC requirements, but there are many low and no VOC options available today. While urethane's solve many problems that plagued epoxies, they still do not bond well to concrete or each other. Urethane's are very chemical resistant and more tolerant to higher temperatures, but do not work well as a stand alone system. Urethane's are best used as topcoats over epoxy systems where high traffic, light stability, gloss, and temperature are issues.
Polyaspartic is similar to urethane, but much faster. Many Polyaspartic products have little to no odor and cure very quickly. While the rapid cure can be a positive, it can also be an extra challenge to installers who are not familiar with working quickly. These products, like polyurethanes, do not bond as well as epoxy to concrete and do not bond well to each other without extensive preparation. Polyaspartic systems can work well, but must be installed quickly and within redcoat windows to make sure each coat bonds to the other. These products are very light stable and remain clear compared to their epoxy counterparts.
MMA cannot be ignored as a relevant option in the resinous flooring industry. This product is probably the best resinous product for exterior work. MMA bonds well to itself and is very light stable. Unlike its cousins, it is not glossy. MMA products cure quicker than any of the other resins and can be a challenge for installers. These resins can be very tricky to work with and have a strong odor that cannot be used in many occupied facilities. While MMA's are popular due to their speed and chemical resistance, the hurdles in their installation limits the availability of quality installers. MMA cannot be used as a topcoat on another system unless it proceeds a total broadcast or completely cured product; it can literally melt other resins.
When you have a project, it is best to consult with a professional to come up with the best system that will work for your environment. The first step is having an understanding about the products, and realize that they all have their strengths and weaknesses. Finding the right combination, can lead to a successful project. For the best results, it is important to have the best product specified so that the installers (bidders) are clear about the expectations and use a product that will give the customer the best finished product for their environment.