Hardwood Floors October/November 2017

AT THE SITE

is in the jug, the greater the crosslinking e ect and the greater the solvent loss to the headspace. What does this mean? More crosslinking and solvent loss will usually equate to higher viscosity, for a coat that does not ow, level, and coalesce as it should. Oil-based nishes are not immune, either. e greater the head space, the quicker a lmwill form over the remaining nish. And yes, like for waterbornes, you may notice a drop in ow and leveling, faster setup, and diminished overall nish application. Oil-based stains are probably the most-common partials in the van. ere are many good reasons for this, including the need to have numerous colors available to make blends, and the possibility that only a small amount of a particular color may be needed to make a blend for a job. Worse, applying stains can mean that a can is open a lot longer than a can of oil or waterbased sealers or stains meaning more solvent loss, a lengthening of the dry time, and (if not mixed periodically) a disproportionate concentration of heavier components in the partial. Worse, if the lid-to-can mating area is not kept clean, the cans will not properly seal, allowing more solvent to escape. Ideally, then, the best option is to predetermine the stain (or oil-based sealer/ nish) amount needed for a job, and then pour the estimated extra o into smaller, “full” cans. Be sure to label these cans clearly, and always use lined cans and lids; otherwise, the driers in the stain can react with the metal of the can, resulting in a gummy product at the can-product interface, higher viscosity and longer dry times. Lined cans usually have a dark gray coating inside the cans and lids; if the metal is still shiny or metallic-gold in color, they are probably not lined. e same goes for oil-based nishes and sealers. If you are worried about solvent loss or otherwise thick product, do not just add water or other solvents to your nishes, stains or sealers without placing a call to your manufacturer rst. ey can tell you if, what, howmuch, and when to add. Usually, since we do not actually know how the product was stored or used, you will probably only get an “uno cial” recommendation. Be sure to have extra product on hand; do not rely on some old partial that has been opened 500 times to get you out the front door of a job. It’s best practice to use fresh nish for your nal coat. In my next article, I will address proper conditions at the job site. Until then, take care of those stains, sealers, and nishes! Do not neglect them, before, during transport, or on the job. Because, hey, what your dad always told you really is true: “If your nish ain’t happy, ain’t nobody happy.” Ethan Erickson is a Chemist at Arboritec USA in Greenwood Village, Colorado. He can be reached at Ethan.Erickson@arboritec.com.

Further, waterborne nishes are o en packaged in plastic jugs which, unlike metal cans, are still somewhat air/water permeable. Elevated temperatures can increase the permeability, as a higher percentage of air/water/solvent passes through the jug. Obviously, oxygen-crosslinked (“one-component”) nishes and sealers are a ected the most. However, don’t discount polyisocyanate hardener bo les, either – polyisocyanates readily react with water, losing crosslinking e ectiveness. Also, added heat speeds up the loss of solvent through the hardener bo les. e end e ect is a thicker (or yellowish) hardener that will not only be harder to e ciently mix into the product, but will also be less e ective at crosslinking with Part A and developing properties. (Should you encounter a hardener that is either yellowish or thick, avoid using it – get a new one.)

Although it is a good idea to store all nishes out of direct sunlight, this is even more important for UV-cured nishes. Since the sun emits the entire spectrum of UV light, it is just common sense to keep UV nishes away from it; even if they are behind a window that blocks 99 percent of UV light, and even if they are in their jugs (which are o en darker/denser plastics, to help block UV rays). It is best to store them in their jugs, in the cardboard carton, away from sunlight. Finishes are not so delicate that they will crumble if storage temperatures or RHs are not ideal 100 percent of the time. However, by storing them how they should be stored, you are only stacking the odds in your favor. AN OPEN-AND-SHUT CASE Every time that you open a nish/sealer/stain jug, you essentially replace the air at the top known as the headspace. Consider that one-component nishes or sealers are usually oxygen-crosslinked. So, if you are replacing the air every time that you open the cap, that means that you are adding more oxygen for the nish to crosslink with, not to mention some solvent loss, both from the open jug and into the “new”/solvent- free headspace. Further, the less nish/more headspace there

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