Glossary Term
DFT (Dry Film Thickness)
DFT means Dry Film Thickness, the measured thickness of a paint or coating layer after it has dried or cured on the substrate. In yacht and superyacht coating work, DFT is one of the main quality-control values for primers, build coats, and finishing systems because protective performance depends on having enough coating on the surface, distributed within the specified tolerance range. ISO 19840 describes DFT verification against nominal dry-film thickness on rough surfaces and ties it to measurement method, inspection areas, and acceptance criteria.
The term matters on underwater coating systems, topside paint, tank coatings, machinery-space coatings, and structural corrosion-protection work. Too little film can reduce barrier protection, shorten coating life, and expose edges and peaks of the blast profile. Excessive film can create curing issues, solvent entrapment, cracking risk, or finish defects, depending on the product and build sequence. ASTM D7091 and related AMPP procedures show that DFT is measured nondestructively with coating-thickness gauges and assessed by a defined sampling method, not by visual judgment.
On yacht refits, DFT sits inside the wider painting control package alongside surface preparation, environmental readings, stripe coats, recoat windows, and final appearance. A glossy finish may look complete while the protective film build underneath is out of range. That difference is one reason serious coating specifications treat DFT as a technical acceptance item rather than a cosmetic note.