CSLB C-33 Painting & DecoratingCoating ApplicationMedium
A painting contractor is preparing to apply a water-based acrylic latex paint to a newly primed interior wall. The manufacturer's specifications recommend a dry film thickness (DFT) of 2.0 mils per coat. The paint has a volume solids content of 40%. What approximate wet film thickness (WFT) should the contractor aim for to achieve the specified DFT?
- A5.0 mils
- B8.0 mils
- C3.5 mils
- D6.5 mils
Show answer & explanationAnswer & explanation
Correct answer: A. 5.0 mils
To achieve a specific dry film thickness (DFT), the wet film thickness (WFT) must account for the volume solids content of the paint. The formula WFT = DFT / Volume Solids (as a decimal) is used. In this case, WFT = 2.0 mils / 0.40 = 5.0 mils.
Why the other options are wrong
- B. This calculation is incorrect and significantly overestimates the required WFT.
- C. This calculation is incorrect and does not properly account for the volume solids.
- D. This calculation is incorrect and significantly overestimates the required WFT.
Wet Film Thickness (WFT) Calculation
The calculation of the required wet film thickness to achieve a specified dry film thickness, considering the paint's volume solids content.
- WFT = DFT / Volume Solids (as a decimal)
- Volume solids represent the percentage of the coating that remains after solvents evaporate.
- Measuring WFT during application helps ensure proper DFT and coating performance.
Memory trick: Wet film, dry film, solids percent, simple math, get it done.