Since its introduction over eight years ago, Polyurethane 250 has proven itself as one of the most versatile and dependable architectural concrete sealers on the market today. With over 20,000,000 square feet installed, this field proven and time tested sealer has become the first choice for many of our industries top professionals. What is not to love? Polyurethane 250 offers superior adhesion to a variety of substrates and all forms of architectural concrete from slate and saltillo tile to concrete pavers. In terms of performance, Polyurethane 250 has solvent based acrylics beat hands down! It has superior abrasion and chemical resistance and exterior gloss retention typically two to three times that of solvent based acrylic. Combine these properties with a coating that is so easy to install that even the most inexperienced installer can use it successfully. It is no wonder that Polyurethane 250 is one of our most popular products. 

 

by Daniel Owen,

Vice President of Arizona Polymer Flooring

 

In this month's application corner we are going to cover some basic application techniques and rules for Polyurethane 250. First things first...surface prep. While Polyurethane 250 offers very good adhesion to minimally profiled substrates, there are occasions where you will need to do some form of preparation beyond machine cleaning. These would typically be power troweled concrete floors that are burnished or floors where cast on color hardeners are used. In the case that the concrete is too tight or dense to receive the coating it will be necessary to do a light diamond grind or acid etch to open up the concrete.
 
When applying Polyurethane 250 I recommend using a "thin to win" motto, this is truly a scenario where more is NOT better. The coating is designed to go down at 300 to 400 square feet per gallon on smooth surfaces. It should be 225 to 275 square feet per gallon on textured surfaces. Over application will ultimately lead to failure due to solvent being trapped in the film. This problem will typically manifest itself as a blister where the coating is thick and ultimately loses adhesion as the solvent migrates out of the film.  In extreme situations the entire project will be soft and eventually lose adhesion due to solvent entrapment. The most common application tools used to install Polyurethane 250 are a brush and roller. For smooth concrete I recommend using a 3/8th nap roller cover.  Textured surfaces such as exposed aggregate, stamped concrete or concrete pavers will require a ½ to 1 inch nap roller cover depending on how deep the texture of your substrate is.
 
I find that using a dip and roll method on both smooth and textured surfaces works best. While spraying is not as typical, it is a viable method for the application of the Polyurethane 250.  For small projects, an HVLP sprayer works great and for larger projects, conventional airless sprayers may be used. If you use an airless sprayer the recommendation is that you back roll the coating to insure an even finish.
 
Now for the question I get asked the most: Can I use a pump up sprayer to apply the Polyurethane 250? The answer to that is twofold. No, you cannot apply it this way "as is" because the solids are too high. However, you can reduce it with acetone 50-100% and it will go through a pump up. But please keep in mind that when using a low pressure sprayer it is easy to over apply or leave puddles and this could ultimately lead to failure. Extra care must be taken if you choose to use this application technique because it can be very problematic. I hope you all found this information useful.