ASTM D1640/D1640M :- Drying, Curing, or Film Formation of Organic Coatings

These test methods cover the determination of the
various stages and rates of film formation in the drying or
curing of organic coatings under laboratory-controlled conditions of air temperature, (low, ambient, and/or elevated) and/or
humidity. Procedures for assessing drying under prevailing
conditions of temperature and humidity in the shop and field
are also described.

Substrate, Coating Application Method, and Film

Obtain agreement between the contracting parties as to
the substrate, wet film thickness (WFT), and application
method for testing the specific coating involved. The product is
tested as manufactured (without reducer, unless otherwise
agreed upon by contracting parties). Unless otherwise agreed,
the thickness of the cast film shall conform to the coating
manufacturer’s product data-sheet. If the wet film thickness is
not stated on the manufacturer’s product data sheet, it can be
calculated using the formula in 4.1.1 based on the manufacturer’s recommended dry film thickness (DFT) and percent
non-volatile by volume (% solids by volume). If this information is not provided, contact the coating manufacturer to obtain
the recommended wet film thickness for testing.

How to calculate WFT

WFT = (DFT ÷ % Solids by Volume )

ASTM D1640/D1640M :- Drying, Curing, or Film Formation of Organic Coatings

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