D10, D50, D90 and Dmax are four important parameters used to describe particle size distribution.

They are commonly used to describe powder materials, granules, etc. They indicate the proportion of particles of different sizes in the whole particle population.

D10: It indicates that 10% of the particles have a particle size smaller than this value.

D50: Also known as “average size”, this means that 50% of the particles are smaller than this value. D50 reflects the average size of the entire particle population.

D90: It indicates that 90% of the particles are smaller than this value, D90 mainly reflects the proportion of larger particles in the population, and can be used to assess the roughness of the population.

Dmax: It indicates the largest particle size in the cluster. Dmax can reflect whether there are oversized particles in the cluster, whether these large particles meet the requirements of the equipment, or whether they may have an impact on the performance of the product.

– Mean particle size: represented by D50.

– The width of the particle size distribution: The difference between D90 and D10 (called Span) reflects the width of the particle size distribution. The larger the Span value, the wider the particle size distribution and the greater the difference in particle sizes.

– Content of large particles: D90 can reflect the content of large particles.

– Content of fine particles: D10 can reflect the content of fine particles.

– Presence of maximum particles: Dmax can reflect the presence of the maximum particles.

• High resolution equipment can more accurately distinguish the size of particles, and the consistency of multiple measurements is more stable. Lower resolution equipment will not be able to clearly distinguish between particles of similar size and will result in larger errors. When multiple measurements are taken on the same batch, particles of different sizes are easily grouped into the same category, resulting in poor repeatability of the results.
• Higher sensitivity devices can more accurately capture smaller particles or individual large particles. Low sensitivity devices are less responsive and have difficulty detecting specific particles, resulting in either a larger test result than the true value or missing of a large particle, resulting in inaccurate results.

The particle size tester we use at Jolin Corporation is Omec LS-609.

• During the production process of luminous powder, accurate particle size detection results play a decisive role in controlling its particle size range. The smaller the particle size range of the luminous powder is, the smoother the production will be after mixing with the medium, the better the coverage in the end product will be, and the more translucent the luminescence effect will be. Otherwise, it is prone to presenting a mottled state.
• The particle size of luminous powders is often expressed as D50 when evaluating them. Here the value of D50 is often a range rather than an absolute value. In most applications, D50 is sufficient as a reference. However, in some special applications, such as ultra-thin coatings, ultra-fine fibers, ultra-fine spray gun calibers, etc., attention needs to be paid to D90 and Dmax, which may affect the smoothness of the product surface, the structural properties, or the production process.