This sealer was over applied. It should have been applied 1 to 2 mils thick, but was likely 20 to 30 mils thick.
Photo credit: Decorative Concrete Resources
Newer sealer formulations dry faster, especially in warmer temperatures.
Photo credit: Decorative Concrete Resources
Just over a year ago, a group of industry professionals met to discuss the large amount of reported problems with acrylic sealers, especially those being used in the decorative concrete field. The American Society of Concrete Contractors (ASCC) assembled a talented group that included contractors, distributors, manufacturers, raw material suppliers and the trade press. The group immediately focused on solvent- and water-based acrylic sealers that are used on the vast majority of decorative projects and seemingly were the center of the most issues.
Entering this event many felt that the sealer manufacturers needed to arrive with full protective gear and pads for the verbal beat down that was likely to occur. Contractors quickly shared horror stories that included upset customers, stripping and recoating, and lost time and income while distributors and manufacturers complained about the inability of contractors to follow directions. However, before an all out brawl could commence, cooler heads prevailed and presentations were given to educate each other on a wide variety of sealer topics. The topics covered sealer types, VOC laws' effects on sealers, troubleshooting and application methods.
During these highly educational presentations many in the room could see a mood shift taking place. The knowledge shared in the presentations and in the small breakout groups that were formed seemingly found an extremely simple but highly effective answer to the bulk of the reported problems. Manufacturers began to realize that although governmental interference may have forced them to make changes to their product, they probably had not passed that information down through the distributors to the end users as effectively as they could have. Distributors started to realize why they had been feeling caught in the middle of being loyal to their customers, but wanting to trust the manufacturer’s product they have been purchasing. Finally, contractors understood why the methods they have used for years might not be applicable with the products available to them today.
What the group realized is the answer to successful sealer application is "thin to win." Today’s sealers must be applied by the contractor in thin applications. The group also acknowledged that manufacturers and distributors needed to better promote the absolute necessity that today’s sealers must be applied in multiple thin coats and in a tighter range of conditions than suggested in the past. Finally, contractors must strictly follow the installation guidelines and understand the old adage “it has always worked for me in the past” is no longer relevant.
It seems like we have always been told that two coats of thin sealer are better than one, but that has never been truer than it is today. For sealer success, contractors must apply two coats of sealer at 1 to 2 mils of thickness each. A mil is 1/1,000 of an inch, or the typical equivalent of a grocery shopping bag or a dry cleaner bag. This allows moisture vapor to properly pass through and reduce the likelihood of efflorescence. When troubleshooting sealers, overwhelming cause of failure is coating thickness. This is especially true when discussing higher solid content (greater than 25 percent) sealers where a high gloss or sheen is desired.
Not to be forgotten in this discussion, water-based sealers have always been prone to thickness-related problems. Opening a pail of milky white “clear” sealer intimidates many contractors, but as we move toward a "green" oriented society the use of water-based sealers will dramatically increase. Water-based sealers are good products that simply take a little care and proper application technique to get right. Application at the rates recommended by the manufacturer (generally 350 to 400 square feet per gallon) are critical The consequences of over application is a white surface that is likely going to have to be mechanically removed. The process is not tough, but solely takes a contractor willing to follow basic instructions to achieve a solid finished coating.
Consequences of environmental regulations
Changes have been made in many sealer formulations due to regulations from our government that center on VOCs (volatile organic compounds). VOCs are released as a gas from the sealers we use, as well as from many cleaning supplies, paints, pesticides and building materials. In our industry the rule changes meant that our solvent-based sealers needed to contain less xylene and more acetone or other fast drying solvents. Xylene has been the main carrier for years to spread and evenly lay out the resin that forms the sealer coating. It worked well because it evaporated slowly giving the resin time to properly form a film. Xylene’s primary replacement is acetone, a solvent that evaporates five times or more faster than xylene which is important for the contractor to understand.
Just about every person has used acetone. It is found in everyday items such as markers and finger nail polish remover, both items where the liquid quickly evaporates. Faster drying solvents may have virtually no effect on sealer performance, but they create many other situations that will create problems for the contractor. The biggest is that the faster drying time sometimes do not allow for the resin to properly form its film. When the film has not properly formed it will lead to adhesion problems, discoloration and general sealer failure. Many projects that could have been previously sealed in the warm afternoon sun must now wait for a cooler evening or morning to be completed. Contractors are more likely to see roller marks, spider webbing coming from their roller and surface blistering due to the newer solvents.
Contractors may think that the "thin to win" answer overly simplified, but they should be thankful that all they are being asked is to do is follow recommended coverage rates and weather related guidelines. If they acknowledge and adapt these practices, they should expect to see a reduction or hopefully an end to the sealer issues that have plagued them in recent years.
To continue the education process and help bridge the communication gap between the manufacturer, distributor and contractor, the ASCC Decorative Concrete Council is developing Sealer Selection & Application Guide. The guide will not only help contractors choose the correct product for their project but will explain the terms used and best methods for application. An entire section will be devoted to sealer troubleshooting and repair methods. A large amount of photographs will demonstrate many of the signs seen on sealer failures, and correction methods will be offered. Look for this helpful guide soon at www.ASCConline.org and at most major concrete events.