FED-STD-141 Paint, Varnish, Lacquer And Related Materials: Methods Of Inspection, Sampling And TestingThis standard elaborates the methods used to determine the physical and chemical properties of paint, varnish, lacquer, and related materials. The purpose of this standard is to establish standardized testing methodologies and to eliminate unnecessary or undesirable variations in test results when evaluating a product??s adherence to specification requirements. If any variation or modification of the methods established in this standard is required by any specification, the procedures listed in the specification will take precedence. Any conflict between this standard and any particular specification will be resolved in favor of the specification.

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METHOD 6241.2

March 22, 2001

INFRARED REFLECTANCE FROM SPECTROPHOTOMETRIC DATA

1. SCOPE

1.1 Scope. This method is designed to provide a measure of infrared reflectance. The effective

infrared reflectance of a specimen for a specified wavelength interval and for specified geometric

conditions is dependent upon the spectral composition of the incident energy, the spectral

sensitivity of the receiver, and the spectral reflectance of the specimen. This method should be the

basic method for the measurement of infrared reflectance and in case of dispute; the results obtained

under this method should govern.

2. APPARATUS

2.1 Spectrophotometer. Use a spectrophotometer that determines the spectral characteristics of

the test specimen within the applicable limits of the infrared spectrum. Use a photoelectric type

apparatus suitable for determinations throughout the applicable wavelength interval. Design the

apparatus to minimize the effect of stray energy by introducing stray energy filters or use double

dispersion prisms (see 6.1). Adjust the direction of irradiation to be nearly perpendicular to the

irradiated face of the test specimen and view hemispherical or the converse. Use split widths of the

monochromator that are sufficiently narrow throughout the applicable infrared spectrum to insure

that the spectral characteristics of the specimen are not appreciably altered when narrower slit

widths are used.

2.2 Standard. Smoked or pressed MgO or pressed BaSO4 prepared according to Recommended

Practice for Preparation of Reference White Reflectance Standards, ASTM E259.

3. REAGENTS

3.1 Reagents. None required.

4. PROCEDURE

4.1 Irradiating and viewing. If glossy samples are to be measured, the specular components of

reflected energy shall be excluded wherever possible.

4.2 Test specimen. The area of the test specimen viewed shall be sufficiently large to be

representative of the test specimen, textured specimen in particular.

4.3 Calibrations. The calibration of the photometer scale shall be carefully checked at reasonable

time intervals in a manner to insure accuracy over the entire range. Glass filters shall be used for

this purpose. The wavelength calibration shall be checked frequently to insure accuracy. Spectrum

lamps shall be used for this purpose.

FED. TEST METHOD STD. 141D