With the majority of adhesives for resilient flooring being pressure-sensitive, the problem of show-through has become greater than ever before. What can be done to combat this problem? Read on for some common problems and solutions to this issue.

Adhesive overlap. Adhesive overlap is a major concern. It is an aesthetic problem magnified by gloss finishes. It’s amazing how many times I see a flooring issue of this type in a hospital. I hear the same concerns expressed by the staff over and over again. They often have no idea how much a high-gloss finish will accentuate even the slightest irregularity in the material, adhesive or substrate. Their only concern seems to be how shiny the surface of the floor is. And at almost any hospital, you will find a huge amount of low-level lighting, which just exacerbates the whole issue.

Adhesive gapping. The opposite problem is a gapping of the adhesive that shows through. The object when applying is to bring the adhesive close enough to eliminate the overlap and eliminate the valley, which is opposite to the overlap of adhesive. If this is done incorrectly, either one – the overlap or the valley – will show through.

Incorrect trowel notching and rolling. The correct use of trowels for the proper application of adhesives has always been a concern within the industry. When trowels wear down, they do not apply enough adhesive. Then they are either re-notched and leave an irregular spread or the incorrect notch is used, which leaves either too much or too little adhesive. Finally, and I cannot stress this enough, rolling the material thoroughly with the proper weighted rolleris imperative. It sounds elementary, but if you perform this necessary step incorrectly you will have problems.

Paint roller application. Several adhesive and flooring manufacturers have recommended trowel-applied adhesive to be rolled with a short nap paint roller to flatten out the trowel ridges. I have witnessed this recommendation but feel it does help stop the trowel ridge show-through problem. Many installers who have used this method find it works well, however.

The downside is it takes a little more time, but there are benefits as well. The adhesive will dry-to-touch quicker, and because there is a larger bonding surface than trowel ridges a better bond is achieved. I also see more installers using this method for VCT tile installations. To be successful, the installer must keep the roller clean and prevent it from leaving balls of dried adhesive on the finished spread. An easy way to do this is by keeping the roller wrapped in a piece of plastic to keep the adhesive wet and fresh.

Spray application. The most recent method is the spraying of adhesives for resilient materials. This is not a new method for applying adhesive, as it has been used with carpet for decades. However, when used for resilient there are two main concerns: The blowing of debris creating bumps beneath the material’s surface, and any unevenness of the spray showing through the material. If those two concerns can be eliminated then the spraying of an adhesive may have a major place in the resilient flooring industry.

Adhesives that are designed to dry-to-touch can be sprayed smoothly and evenly, and then the likelihood of show through can be almost eliminated. Attention will have to be paid to keeping the spray smooth and even, with special attention paid to overlaps of the spray.

Another advantage is if the spray adhesive can be applied thin enough, the likelihood of indentations that occur in the adhesive line can be kept at a minimum. Finally, if it will get the installer off his knees, it will save him from the constant wear and tear of this job. I do think it is going to take a specially formulated adhesive to meet all of these criteria.

The application of adhesive properly done is still the biggest challenge we have in the resilient flooring industry. There are a lot of hurdles to overcome, but rolling and spraying are growing in popularity and are helping to overcome some of the industry concerns. No matter what method you ultimately use, remember to do it right and follow the manufacturer’s recommendations. Don’t take shortcuts that do not work.