What is paint mil thickness (DFT)?
Mil thickness, or dry film thickness (DFT), is the depth of a paint coating measured in thousandths of an inch (mils), used to verify proper application and durability of paint jobs.
A mil is one-thousandth of an inch (0.001"). Dry film thickness, or DFT, refers to the depth of paint applied to a surface after it has dried. Paint applicators measure DFT using a specialized gauge to ensure the coating meets the manufacturer's specifications and the job requirements.
Why DFT matters: Paint performance depends on coating thickness. Too thin, and the paint fails to protect the substrate, cracks prematurely, or leaves visible holidays (missed spots or areas of inadequate coverage). Too thick, and paint may sag, crack during curing, or waste material. Most residential exterior paint requires 1.5 to 3.0 mils DFT per coat, depending on the product and surface. Primer, base coats, and topcoats each have their own thickness targets.
Checking DFT is standard practice for quality control. Applicators in Rock Hill and across the region use DFT gauges (both destructive and non-destructive types) to spot-check coverage during and after application. This verification protects both the contractor's reputation and the client's investment by confirming the coating will deliver the durability promised. Compliance with DFT specs is especially important on commercial or industrial projects where warranty and performance standards are strict.