Hardwood Floors December 2017/January 2018

AT THE SITE

By Ethan Erickson

Love and Care of Your Finishes and Sealers PART 2 : ON THE JOB S I TE

Love and care of your sealers and nishes does not end when you get to the job site. You have taken care selecting and housing them, and have taken them for a drive. Now, you have just carried them across the threshold of a new house (so don’t tell them that you will be pu ing them down and leaving in a ma er of days). What now, Romeo? Keep reading. NUTS AND BOLTS First and foremost, know and follow the directions for the product, including, but not limited to: • whether to stir, shake or “gently rock,” • how long to mix, • when to add the cross-linker or hardener (for two-part

HOT COATING Hot coating is not always bad, but do always defer to the manufacturer instructions for the limits: “May be recoated a er X hours…,” “Allow to dry X hours…,” etc. ese are set to ensure that enough drying and coalescence have taken place to hinder neither the integrity of the rst coat nor the application of the next one (adhesion is usually not an issue with the successive coats with waterbornes). When coated too early, isocyanate crosslinked nishes, more so than one-components, can be more “grabby,” as that is exactly what they are doing: grabbing the still-reactive surface of the preceding coat, as they crosslink with those components to a higher degree than if that coat was drier. One consequence is to prevent the coat from owing out and leveling like it wants to, from those li le chemical “handshakes” reaching up from below. Most manufacturers recommend no more than two waterborne coats per day. is limit is because each coat drastically limits the rate at which solvent/water can escape and oxygen can permeate to cure the bo om coat. is decrease is closer to exponential than it is to double. Imagine, then, the decrease in permeability a er a third coat. is translates to a slowing of the hardness, chemical resistance, and other properties development – a problem for oors used too quickly (because people always stay o their oors for as long as contractors tell them to). If you are going to do more than two coats per day, stack the odds in your favor. Try to use isocyanate or aziridine crosslinked nishes for the intermediate coatings, as these are not dependent on oxygen ltering through to crosslink and cure, like one- components. Also, wait the longest time between the rst and second coat – not between the second and third coat. Remember that each successive coat typically drastically reduces the solvent and oxygen permeability of the previous coat(s) – the longer you can wait a er the rst coat, the faster your systemwill cure, and achieve the properties on which you sold your customer.

products), how to mix, and for how long, • how long to let it rest before application, • application tools, • coverage rates, • recommended application temperatures and relative humidity, • substrate preparation, • products to use before/a er said coat, • when to apply said/succeeding coats, • abrasion between coats, and • howmany coats may be applied in one day.

Remember, there are reasons why those instructions are on the label – testing has proven that following themwill yield the highest probability of success. Of course, circumstances frequently occur that fall outside the guidelines; do not be afraid to call your manufacturer. We may not enjoy you interrupting a scintillating sales meeting, but we really do want to help you to be successful. I should note here that manufacturers are only liable for product replacement, not your labor, meals, gas, golf rounds, pedicures, or other resand/recoat expenses. A few of the above bullet points bear further exploration.

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