7.1 Accurate determination of thickness is important for identification purposes. Thickness is related to weight and must be known in order to calculate apparent density and the dielectric strength.

7.2 Thickness variation affects the quality of roll winding and is useful in judging the uniformity of mica paper particularly with respect to dielectric breakdown voltage, impregnation time, and thickness of the end product.

1.1 These test methods cover procedures for sampling and testing untreated mica paper to be used as an electrical insulator or as a constituent of a composite material used for electrical insulating purposes.

1.2 The procedures2 appear in the following order:

ASTM

Method

Procedures

Sections

References

Apparent Density

12

...

Aqueous Extract Conductivity

32 and 33

D202

Conditioning

4

D685

Dielectric Strength

16 – 19

D149

Impregnation Time

20 – 24

D202

Moisture Content

26 – 28

D644

Roll Quality

25

...

Sampling

3

...

Tensile Strength

13 – 15

D828

Thickness

6 – 10

D374/D374M

Weight

11

D646

Weight Variability

29 – 31

...

1.3 The values stated in inch-pound units are to be regarded as the standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.