Particle characterization is the process of analyzing particles by particle shape, size, surface properties, charge properties, mechanical properties, microstructure and many more measurement parameters. There is a broad range of commercially available particle characterization techniques that can be used to measure particulate samples.

Size and shape are important attributes that affect the behavior of particulate substances. Spherical beads are easily and commonly characterized by a single size measure: “Diameter”. Irregular shapes are more difficult to characterize given their multi-dimensional structure. Powders used in manufacturing, for example, requires several measurement parameters to ensure flowability, packing and other performance functions.

Particle Size and Shape Analysis are analytical techniques by which the distribution of sizes and shapes in a sample of solid or liquid particulate material is measured and reported. Particle size and shape analysis are an important tool in characterizing a wide range of final-product performance for quality control in many different industries, including paints, building materials, pharmaceutical, food industries and toners.

Statistical results are generally given with histograms of Because of the large number of particles, size and shape data are statistical. Histograms are the best way to portray statistical distributions of a variable or measure, and there are various means and measures of spread to characterize a distribution using just a few numbers.

Size Distribution histograms

To show the sizes present in a sample, the size range is divided into small size classes or “bins”, and we count the number of particles present in each size bin. The graph below is a size histogram, and it presents a good picture of the actual distribution. Size data is normally shown graphically on a log scale axis, to better show the small sizes.

Particle size information is typically displayed either in a volume-weighted distribution or a number weighted distribution. Both are equally important to view. It is important to understand that the volume-weighted histogram will emphasize the larger particles and the number-weighted histograms will put emphasis on the fine particles.

Circularity, Smoothness and Aspect Ratio histograms

Non-size data such as circularity, smoothness, Opacity, etc. are shown on a linear scale. These shape measurements are typically called fraction measures that will be a measure from zero to one.  These histograms have very fine divisions or bins increasing the ability to report accurate results.

Also shown in a linear scale is aspect ratio.  Shown below is bounding rectangle aspect ratio. Particle shape analyzers will typically have several different types of aspect ratio measurements. The user can select which aspect ratio measurement is more appropriate based on the shape of their particles. Aspect ratio measurements are typically between 1:00 and 10 but can be user defined. The bin spacing can also be user defined.