What is dry film thickness?

Dry film thickness, or DFT, refers to the depth of a hardened coating measured in mils (thousandths of an inch). When a painter applies epoxy, polyurethane, or other protective coatings to floors or surfaces, the wet product contains solvents that evaporate as it cures. DFT measures only the solid material that remains once curing is complete.

For epoxy floor coating, DFT directly affects durability and performance. Thinner coatings may peel, wear through faster, or fail to protect the concrete substrate from chemicals, abrasion, or moisture. Typical commercial epoxy floors in Bridgeport facilities are specified between 6 and 10 mils, though heavy-duty warehouse or industrial applications may require 12 to 15 mils or more. Insufficient thickness cannot provide the same level of protection or longevity.

Professionals verify DFT using an electronic gauge, also called a mil gauge or coating thickness meter. The tool measures the dry layer by placing a probe against the cured surface and reading the result instantly. Because DFT is critical for warranty claims and performance guarantees, painters and contractors on the job check it at multiple points across the floor to confirm the coating meets specification. Documenting these measurements is standard practice for quality control.