Standard · Adhesion, cure and holidays
ASTM D2240
Durometer hardness (Shore A and Shore D).
ASTM D2240 measures indentation hardness with a durometer. Coating inspectors use it on thick, chemically resistant films and elastomeric linings: Type A for soft materials, Type D for hard ones.
The procedure
- The specimen should be at least 6 mm thick, unless thinner material is known to give the same result. On a thin film the hard substrate below falsifies the reading.
- Keep each reading at least 12 mm from an edge and the readings apart from each other.
- Read the dial within one second of firm contact, unless the specification gives another time.
- Take five readings and report their mean or median.
A hardness value on its own says little. The specification or the product data sheet gives the hardness a cured film should reach.
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This page describes the subject of ASTM D2240 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.