Density Analysis

Density - Container Diagram
Density - Granule Diagram

Density is defined as mass of a sample or body divided by its volume. This value is typically expressed in kg per m3 or g per cm3 for solids, as well as in g per mL for fluids at a given temperature. Alternately, the dimensionless ratio between a sample density and the density of a reference material, termed specific gravity, may be reported.

Changes in the density of a raw material or product can indicate changes in its structure or composition, which could lead to performative differences. As such, density is an important parameter for product development as well as quality control in many industries ranging from pharmaceutical, food and beverages, cosmetics, agricultural, environmental, plastics, ceramics and industrial building supplies.

There are several types of specialized density terms as utilized by different industries, depending on what constitutes the sample volume. Aligning the appropriate type of density with the desired applications is particularly important for porous solids or granular materials. Below are simplified definitions of the different types of voids that may be included or excluded from the sample volume.

  • Intraparticle void: the void within each sample piece or granule. The terms below can also be applied to single sample piece, core, or chunk.
    • Open pore: pores accessible from the sample surface
    • Closed pore: pores inaccessible from the sample surface
  • Interparticle void: the space between the granules or particles
  • External void: roughness or irregularities on the sample surface

PTL can advise on the most appropriate techniques suitable for your needs.  We have capabilities for density determination using a variety of techniques. PTL can also follow standard methods from various organizations such as ISO, USP, and ASTM. Listed in the table below are examples of common density types. The void volumes included in the sample volume are marked with an X.


Density Types
Solid Material Volume
Intraparticle Void Volume
Interparticle Void Volume
External Void Volume
Closed Pores
Open Pores
Bulk Density
X
X
X
X
X
Tapped Density
X
X
X
X
(Reduced by tapping)
X
Envelope Density
X
X
X
X
Skeletal or Apparent Density
X
X
True Density
X

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Click the button to the right to learn how to submit sample material for particle size and characterization analyses. If you have more questions along the way, please contact us.