Coating How-tos, through Thick and Thin
Tracking wet film thickness throughout a project—to avert dry thickness curveballs later on—is the focus of the newest PaintSquare Video Learning Center installment.
"Calculating Wet Film Thickness or WFT" is one of 19 videos in the original instructional series, which explores multiple aspects of protective coatings work.
Created and narrated by experts at KTA-Tator Inc., the series of concise videos covers a wide range of topics, from quality-control and health and safety issues, to basics on the proper use of coatings instruments.
Taking WFT Measurements
In this video (5:18), KTA's Ken Trimber describes how to calculate the target WFT based on three key values and two formulas.
Most coating specifications require the dry film thickness (DFT), "but the painter can't wait until the next day to determine whether the proper thickness has been achieved," Trimber says.
Therefore, WFT measurements must be taken as the coating is applied so that adjustments to the application process can be made.
Occasionally, the target WFT is listed on the product data sheet, but that's not always the case, so it's important to know how to calculate the target WFT for both thinned and unthinned coatings, Trimber notes.
Taking WFT measurements is necessary because "the painter can't wait until the next day to determine whether the proper thickness has been achieved," Trimber says.
Adding thinner to a coating increases its volume and affects the thickness of the wet film; however, it is not part of the DFT because it evaporates into the air, Trimber explains.
3 Key Values
In order to calculate the target WFT, three key values are needed:
Based on these three values, Trimber gives the two formulas to calculate the WFT and demonstrates how to use them with example equations.
PaintSquare expects to present a new Learning Center video from the series every two weeks. Future topics in the series include:
The full series will be available free in the PaintSquare Video Learning Center.