In order to better understand and explain the differences between the various grades of multi-purpose adhesives that are currently sold in the overall market, it is important to first define the type of adhesives to which we are referring. Since there are many different types/kinds of adhesives, e.g. latex/rubber, acrylic, epoxy, polyurethane, etc., I will only be referring to latex-based adhesives that are typically used for the installation of most carpeting and felt-backed sheet goods. Keep in mind that even though these floor covering adhesives are often labeled multi-purpose, they are neither all-purpose nor for all flooring under all conditions. It's always good to read the adhesive manufacturer's technical information before beginning the installation to make sure that the adhesive is the right product for the floor covering that you are installing. The manufacturer knows its products best, especially its products' limitations. Many manufacturers are trying to make adhesives less of a commodity by designing better adhesives with enhanced performance, e.g. anti-microbial protection, green labeled, low odor, non-staining, quicker green strength, firm vs. soft setting, etc.
The adhesive industry is currently working on performance standards through various associations. This work will no doubt help everyone in the market better choose what adhesive they need for a particular intended use. The primary function of any adhesive is it's holding power. How much holding power or adhesion is needed is predominantly determined by type of floor covering, intended use (residential, light commercial vs. extra heavy commercial) and expected life of the installation. There is no doubt an installer needs to use a better adhesive in airport corridors as compared to a lightly used office filing room. At times, a good grade adhesive can be the right choice.
Typically, an adhesive's grade is determined by how much latex or rubber is in the adhesive as well as how the rubber is modified for use and protected from abuse. The more latex used, the more adhesion achieved, and the better the long-term performance. Think of it as more octane in gasoline or more cylinders in an automobile's engine. Yes, I know, it's not that easy. Quality and process controls are a must. Written performance standards will help put the focus on performance rather than price. Rather than "good, better, best", we may spec product as Type 1 vs. Type 2 or Grade A vs. Grade B. Once the right adhesive is determined by intended use, then we can all market the added features and benefits we build into each of our adhesives. Warranties can then be built around performance, rather than giving our customers a better warranty for more dollars spent. Proven performance rather than price is the way to go.