Plastics Technology Laboratories  

Density and Specific Gravity

ASTM D792, ISO 1183

Click on the picture for a larger view

Density is the mass per unit volume of a material. Specific gravity is a measure of the ratio of mass of a given volume of material at 23C to the same volume of deionized water. Specific gravity and density are especially relevant because plastic is sold on a cost per pound basis and a lower density or specific gravity means more material per pound or varied part weight.

Test Procedure:
There are two basic test procedures, Method A and Method B. The more common being Method A, can be used with sheet, rod, tube and molded articles. For Method A, the specimen is weighed in air then weighed when immersed in distilled water at 23C using a sinker and wire to hold the specimen completely submerged as required. Density and Specific Gravity are calculated.

Specimen size:
Any convenient size.

Specific gravity = a/[(a + w)-b]
a = mass of specimen in air.
b = mass of specimen and sinker (if used) in water.
W = mass of totally immersed sinker if used and partially immersed wire.

Density, kg/m3 = (specific gravity) x (997.6)

Equipment Used:
Mettler Balance
Fixture for weighing samples in water

Intertek PTL Overview
Contact Us
Services & Tech Info
Industry Segments
Industry Segments


**Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. For more information please contact a Intertek PTL Technical Representative at . Due to copyright restrictions, we are not able to provide copies of standards. Standards can be obtained from appropriate standards authorities.

Back to Testlopedia