ASTM C562

Moisture in a Graphite Sample

Applicability: ASTM C562 applies to carbon and graphite materials in various product forms including electrodes, blocks, machined components, and powder, where hygroscopic surface moisture must be quantified prior to use or chemical analysis. The method is applicable to samples at or near ambient conditions and is not intended to determine structurally bound or combined hydrogen; samples suspected of containing volatile organic compounds other than adsorbed water require separate analytical consideration.

Purpose: ASTM C562 determines the surface moisture content of graphite by heating a weighed sample at 125°C in a convection oven for 30 minutes and calculating the resulting mass loss as a percentage of the original sample mass. Accurate moisture determination is a prerequisite for correctly reporting ash, fixed carbon, and other compositional properties on a dry basis; it is also used in quality control to ensure that graphite components and powders meet storage and handling specifications, particularly where absorbed moisture would adversely affect electrical resistivity measurements or dimensional stability during downstream processing.