The Causes and Effects of Common Adhesive Problems
Adhesive concerns surface in all types of situations. Often, we believe that the only role an adhesive plays is to hold down a piece of material. But frequently, extenuating circumstances arise to create problems. The following are several of the more common adhesive-related concerns and their possible causes.
Adhesive on the surface of materialsAdhesive on the surface of a piece of resilient material can be a result of many different causes. Sometimes, spilled adhesive is tracked onto the surface of the floor material. Other times, it's due to adhesive oozing or bleeding through a tile joint or seam. The adhesive will be sticky, attract soil and appear dirty. Most adhesives, with the exception of epoxies, can be cleaned from the surface of the material. It is best to attempt to identify the source of the adhesive so that the cause of the problem can be positively identified.
Bleeding of adhesives can occur for a variety of reasons. Among these are:
Compatibility of adhesives with the substrateResidues on the surface of the substrate can cause de-bonding, discoloration and adhesive deterioration issues. Any residue left on the surface of the substrate introduces one more variable that can cause adhesive failure. Some common residues, and the concerns they create, are as follows:
The substrate's porosity often dictates the type of adhesive to use and the amount of open time it requires. Many times, a floor in a renovation project is assumed to be porous when, in fact, the substrate is non-porous. Porosity conditions are of most concern when installing resilient products with a non-absorptive type of backing, such as when heterogeneous- or homogeneous-backed sheet materials are laid over a substrate that has had a moisture remediation treatment and was skim coated with a cementitious underlayment.
Bonding failuresThe causes of adhesive bond failures are varied. Some of the more common situations are detailed below.
Excessive adhesive applicationExcessive adhesive application is usually the result of the installer selecting an improper trowel notch for the job. In fact, the notch trowel is the installer's single most misused tool. All adhesive manufacturers specify the trowel notch requirements for their adhesives and for the type of substrate to which the adhesive may be applied.
So, why is there a problem? Well, if you were using a trowel with 1/16-inch wide and 1/16-inch deep notches spaced 1/16 of an inch apart, and the specifications for the adhesive required a trowel with 1/16-inch wide, 1/16-inch deep notches spaced 3/32 of an inch apart, you'd probably question what harm could come from using the trowel that had notch spacing a mere 1/32 of an inch smaller that what was specified. How could such a minute difference affect an adhesive spread? The answer is almost 20% more adhesive will be applied to the substrate.
Excessive adhesive applied to the substrate is responsible for indentations in resilient material caused by static loads, such as furniture, and rolling loads. Undulations in the material can result from knee, knuckle and footprints that leave permanent impressions in the excessive adhesive film left on the floor. Ridges may also develop in the adhesive during the rolling of the floor. Other problems caused by the application of excessive adhesive include oozing of adhesive, adhesive contamination of seams, bubbles in the floor covering, and curling of materials.
Rolling materials into the adhesiveI hear a lot of comments regarding the use of a roller. To get excess air out from beneath the freshly laid floor covering, some installers use a broom, a wet towel wrapped around a piece of lumber, a wall roller, their hands, and any number of other means. The bottom line is they are too lazy to carry in the appropriate tool - a roller - to complete the installation in the specified manner.
Why do you think a manufacturer would specify the use of a 100-lb. roller if a 25-lb. one would do the job? Why would a manufacturer specify a 150-lb. roller for rubber tile if a 100-lb. roller would suffice? Are manufacturers trying to be difficult? I don't think so! The reason is application of a specific, straight-line static load is necessary to force the material down into the adhesive while maintaining a uniform pressure on the surface of the material. Do you think that could be accomplished with a wall roller? And how do you think the installation will look once it has 10 coats of high-gloss polish applied?
Adhesive removalRemoval of adhesives must be done with the greatest of care. Some adhesives must be completely removed, while others may be removed to a thin residue. In no case should a new adhesive be applied over the trowel notches of an old adhesive.
Adhesives can be removed by either mechanical or chemical means. If there is no asbestos concern with the old adhesive, it can be removed mechanically through the use of some type of power scraper (either a wet or dry method). Chemical removal requires much more attention to detail.
Chemical adhesive removers must be cleaned up thoroughly, because they exert the same removal action regardless of whether they come in to contact with an old existing adhesive or a freshly applied new one. When remover residues are left behind, the results can be disastrous.
Beware of adhesive abatement companies that are not familiar with the flooring industry and its standards. These firms can leave you with what appears to be a clean substrate even when it is loaded with adhesive remover residues that are not readily identifiable.
Other problemsTrowel notch show-through. How many times have you walked into a supermarket and gasped at the trowel notch show-through you see in the floor? This occurs when the installer either uses a trowel with the notches spaced too far apart for the adhesive to be used, or his trowel had worn down and was improperly re-notched so that several notches were made deeper than the others. I have seen instances of this so bad that the vinyl composition tile (VCT) was cracked over the ridge the trowel left in the adhesive.
Material subjected to traffic too soon. Sometimes, after an installation is completed, other tradesmen working at the job site are allowed onto the floor too soon. When the entire job is completed and the floor cleaned and polished with a high-gloss polish, a host of indentations and rolling-load marks becomes immediately apparent all over the new floor. This occurs because the adhesive was never allowed to cure before being subjected to traffic.
Manufacturers specify that a newly installed floor should be protected from foot traffic for 24 hours and from rolling-load traffic for 72 hours. It doesn't matter whether the applied adhesive is latex, acrylic or an epoxy - they all need to be protected.