Standard · Application and film thickness
ASTM D4414
Measuring wet film thickness with notch (comb) gauges.
A notch gauge is pressed square into the wet film straight after application. The wet film is between the last notch that touched paint and the first one that stayed clean.
Two forms of gauge
- Procedure A: a straight notched plate, for about 3 to 2,000 µm.
- Procedure B: a circular gauge rolled through the film, for about 25 to 2,500 µm.
How far to trust it
D4414 itself calls notch gauges neither accurate nor sensitive. A notch reading guides the painter while the film can still be corrected. The specification accepts the dry film, measured later with a DFT gauge.
From the volume solids, WFT = DFT × 100 ÷ VS, with a correction when thinner is added. ISO 2808 lists the same tools as methods 1A (comb) and 1B (wheel).
Use it: WFT ↔ DFT calculator
4 practice items in the members area mention ASTM D4414 (CIP 1: 3 · CIP 2: 1).
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This page describes the subject of ASTM D4414 in our own words; it does not reproduce the standard. For the full text, buy the current edition from ASTM International. Checked on 2026-10-14; errors go in the corrections log. CoatMentor is an independent study aid. It is not affiliated with ISO, AMPP, SSPC, NACE International, ASTM or FROSIO.