Hardwood Floors June/July 2026

AT THE SITE The Importance of Coating Thickness (Continued)

UNDERSTANDING PROPER FILM THICKNESS It is important to note first, the

A typical household with kids and pets should strive for a minimum of 108 to 126 microns of dry film (three coats at 120 microns each) and extreme use floors require 135 to 158 microns of dry film (three coats at 150 microns each).

difference between wet- and dry-film thickness. Wet-film thickness (WFT) is calculated at the time the coating is applied on the floor. Dry-film thickness (DFT) is calculated after drying is completed and the remaining components in the finish have evaporated. The relationship between WFT and DFT is straightforward: the dry-film is approximately the wet-film minus the portion lost to evaporation (this is commonly expressed as the solids content of the finish). For water based finishes with 30 to 35 percent solids content, roughly 65 to 70 percent of the applied coating will evaporate. For example, a coat applied at 100 wet microns will yield 30 to 35 microns dry, while a 120-micron wet coat will result in 36 to 42 microns dry. In the end, setting and use situation for any given floor must be logically and honestly evaluated when choosing the product, its application rate, and the proper application tools. For instance, with our products, in residential settings with light to moderate use, a good benchmark goal is 90 to 105 microns of dry film (three coats at 100 microns each). A typical household with kids and pets should strive for a minimum of 108 to 126 microns of dry film (three coats at 120 microns each) and extreme use floors require 135 to 158 microns of dry film (three coats at 150 microns each). Achieving these film targets requires proper technique, selection of the appropriate tools, having sufficient product on hand, and uniform application from room to room.

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The encouragement for floor finishers to adhere to recommended coverage rates while applying water based or other coatings is

not a ploy or conspiracy to “sell more product.” Rather, it ensures that the intended performance of the coating is achieved, creating a successful outcome for all parties involved. When a homeowner receives a beautifully finished floor,

PHOTO COURTESY OF BERGER-SEIDLE AMERICA

they are happy with their chosen professional and investment. The professional benefits from using a product that performs reliably, and the manufacturer is happy to earn trust and repeat business. Maintaining this cycle of quality and trust is essential for the long-term health of our industry. May the odds be stacked in your favor for successful coating.

Damian Bush is technical director for Berger-Seidle America.

NOTE: 1 micron = 0.03937 mils; 1 mil = 25.4 microns Why the difference matters: Specifications may be written in one unit but measured in the other. Using the wrong unit can lead to incorrect application, quality control failures, or non‑compliance.

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