Dry Film Thickness (DFT) refers to the thickness of a coating (such as paint) after it has fully dried and cured. It is typically measured in microns (µm) or mils (1 mil = 25.4 microns).
In the painting and protective coatings industry, especially in Australia, DFT is a critical quality control parameter. It ensures that the applied coating meets the manufacturer’s specifications for durability, corrosion resistance, and overall performance.
Key points about DFT:
- Measured after drying: Unlike Wet Film Thickness (WFT), which is measured immediately after application, DFT is measured once the solvent or water has evaporated and the coating has cured.
- Affects performance: Too thin a DFT may lead to inadequate protection, while too thick a DFT can cause cracking or poor adhesion.
- Measured using tools: Common tools include magnetic or ultrasonic DFT gauges, depending on the substrate (e.g., ferrous or non-ferrous metals).
Example: If a paint system specifies a DFT of 75 microns per coat, the applicator must ensure that, once dry, the coating measures approximately 75 microns thick to meet the specification.
In Australia, compliance with standards such as AS/NZS 2312 (Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings) often requires accurate DFT measurement and documentation.