What exactly are solids? In waterbased hardwood floor coatings, solids are whatever is left on the floor after the coating cures. Solids are usually expressed as a percentage of weight; a coating with 50% solids will be half gone after it dries. Still
confused? To put it simply, the higher the solids, the more coating you will have left on the floor after it dries. There are several myths floating around the hardwood floor finish industry regarding solids. Keeping this in mind, let’s examine
the three biggest misconceptions about solids.
Myth #1: The more solids, the better.
Solids can be anything that does not evaporate during the curing process, so you have to look at what makes up the solids and what each of them does. Merely comparing finishes by
percentage of solids is not an adequate test of their capabilities and performances. Finish solids are often a blend of several ingredients, each having a specific purpose. Many of these have nothing to do with how long a finish will last. These
various ingredients help the finish resists scuffs, reduce bubbling, improve adhesion, alter clarity, regulate sheen, and last but not least, determine overall durability. Ingredients used to adjust sheen or to control bubbles, for example, may
add to the solids, but they do nothing for the durability.
Myth #2: Taber abrasion tests are always accurate.
The only scientific data less reliable than a Taber abrasion test result is what you get from your local
weatherman. The American Society of Testing and Material (ASTM) states that the accuracy of one Taber abrasion machine compared to another may vary up
to a range of 90% to 106%. This is considered the normal range and means the tests can be off by 100% and still be considered accurate. These results can occur even when documented test procedures are used. In a nutshell, this is why we don’t
value Taber abrasion tests as the one and only way to determine the durability of a finish.
Myth #3: Pure urethane solids are best.
Like the first myth, this one concerning urethane solids is also incorrectly
based on the idea that “if a little of something is good, then a lot must be better.” Many people (and some manufacturers) think omitting acrylic will improve a waterbased coating. We’ve found the opposite to be true, and we
are not alone. Like most everything else you can buy, there are expensive acrylics and inexpensive filler acrylics, and the same is true for urethanes. It is possible to have more expensive acrylics in a finish formula than the urethane
used in the same formula. For flooring applications, urethane resins work best when blended with acrylics.