Standard · Systems, environments and degradation
ASTM D714
Rating the size and frequency of blisters in paint.
ASTM D714 rates blistering by comparing the surface with reference photographs. The current edition is D714-25.
Two scales
- Size: an even-numbered step from 10 down to 0. A 10 means a blister-free film; 8 is the finest blister that naked-eye inspection picks up; 6, 4 and 2 step up in diameter.
- Frequency: Few (F), Medium (M), Medium dense (MD) or Dense (D).
A rating combines both, for example 6M: medium-sized blisters at medium frequency.
The trap
The ASTM size scale runs the other way from ISO 4628-2. In ASTM D714 a smaller number means a bigger blister; in ISO 4628-2 a bigger size number means a bigger blister.
ISO 4628-2 also writes the density first and the size in brackets, for example 2(S2), and its pictures stop at size 2: size S1 is visible only at ×10. Translate a rating from one scale to the other with care, and name the standard in the report.
D714 is in ASTM Volume 06.01, one of the two volumes that the CIP exam guides name as their standards.
3 practice items in the members area mention ASTM D714 (CIP 1: 1 · CIP 2: 2).
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Also published openly: Henkel / CCAI corrosion evaluation legend: ASTM D714 blister size and frequency · WO2022061703A1 (Google Patents): ASTM D714 blister size steps 10, 8, 6, 4, 2.
This page describes the subject of ASTM D714 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.