Illustration 1: Types of carpet backing

The issue of adhesive and backing compatibility has become very complex due to the growing number of carpet mills that have their own private label adhesives and private label backings, not to mention liability disclaimers that specify the specific brands of adhesives that must be used to install their carpets with their new backings.

The contractor's dilemma occurs when he installs the carpets of several different backings and the numerous adhesives required to address the warranty/liability of each installation. Often the contractor who pays for his adhesives finds himself with a multitude of private label adhesives that are unable to be used for the next job.

Then there is the issue of differing performance properties for each of the private label adhesives. The contractor must constantly adjust the way he works every time he uses a different adhesive in order to address the issues of initial tack, open time, spread rates and green strength development.

It is a known fact that many of the private labeled adhesives are not manufactured by the floor covering manufacturers. It is interesting to note that some of the major European flooring companies do have their own adhesive manufacturing capabilities; however, in the U.S. this is not the case. Regarding the floor covering manufacturers recommending their own adhesives, many in our industry believe that the mill is just trying to make an extra buck. I believe that the floor covering manufacturer is "selling a system" by offering the very best premium adhesive with added features, such as antimicrobial protection or water resistance, to reduce the risk of an installation failure.

Regarding carpet backings, the days of jute are gone. Woven polypropylene, such as Action-Bac, is now the secondary backing of choice. Over the last few years, backings have become more complex. We now see the primary and secondary backings fused together rather than applied separately at the mill. We now see a plastic film/membrane fused to the secondary woven polypropylene. This combination can be applied either way to the tufted carpet. This combination provides a different look to the carpet backing. We now see a non-woven fleece fused to the woven polypropylene secondary backing to add softness to the finished product.

These new backings were developed to provide greater tuft bind or greater moisture resistance (spillproof), or greater ease of installation. The changes in the backings involve the use of different adhesives to bond the secondary backing to the primary backing, or improvements to the secondary and primary backings. Most carpet is tufted into a primary backing which is primarily a synthetic woven scrim (See Illustration 1). The yarn is locked into the primary backing by use of an adhesive, mainly latex. Typically a secondary backing is glued to the tufted carpeting to stabilize the product. Backings manufacturers can enhance the performance of the finished product by enhancing the primary or secondary backings. Carpet mills can enhance the performance of the finished product by using different glues to adhere the secondary backing to the primary backing.

The result of these improved backings is that the carpet does not breathe as much as some of the older backings. The carpet is less porous and does not allow as much moisture to travel through it. This includes the wake in the adhesive used to install the carpeting.

Our adhesive company's research indicates that our standard premium multipurpose carpet adhesives can be used successfully; however, we recommend only those adhesives that have high solids (low water content), excellent water and alkali resistance, outstanding initial grab, quick green strength, and good residual tack.

Lower grade adhesives will take longer to dry and cause bubbling problems. When adhesives dry very slowly, their ultimate bond strength will never be achieved. Therefore, a premature failure may occur. Since these new backings are less porous, the adhesive must have the very best water, alkali (for concrete floors) and mildew resistance. Only premium adhesives have these characteristics. Most of the new backings can be successfully installed with non-private labeled adhesive as long as the adhesive is truly premium. I often suggest to a customer to double check that the branded adhesive has the same, if not more, features and benefits as the private labeled adhesive. Also, trust and experience in the company you are working with is very important.

Regarding the liability issue, it is very important to remember that the resilient industry tried tackling this controversy many years ago. In a statement to the floor covering industry, a major resilient manufacturer stated that its warranty was not automatically voided when non-specified adhesives or other products are used in an installation. The company stated that it would stand behind its warranty, even if other products were used in the installation, unless the specific problem that occurs is caused by the use of a non-recommended product or is the result of improper installation. Problems such as delamination and printing irregularities would have nothing to do with the installation, and would not affect the warranty. I believe this statement more than adequately clarified the resilient manufacturer' position. It was and remains fair and well balanced.

Many years ago, a contractor friend asked me what I would do if I were in his shoes. I told him that I would use the private label adhesive if I were installing one or two types of backing from one or two manufacturers. However, if I were installing various backings manufactured by several carpet mills, I would use a national brand of premium adhesives that provided me with the best local service in that market.