| Calculating the size, shape, and mass of microscopic | | | | come in particulates before being emulsified into the |
| particles in a suspension is seemingly a daunting task | | | | household paint matrix, and having the proper size for |
| at best. Particles in the micrometer, or micron, size | | | | the pigmentation particles is crucial. Too large a |
| can move very quickly in an aerosol, for example, | | | | particle and the paint would coat in an uneven color, |
| and determining their size and shape while they are | | | | too small and the pigment may not be brought out |
| flitting about in the dispersion would require | | | | after the paint dries. |
| extremely sensitive instruments. Particle sizing | | | | Laser light backscatter particle sizing is one of the |
| equipment must enter into this ambiguous and | | | | most innovative methods to date. Laser light is a |
| difficult analytical process. | | | | pure coherent light, and the beam can be focused |
| There are several methods for particle sizing. One | | | | and adjusted for nearly any particulate matter being |
| such method is the so-called sedimentation method. | | | | analyzed. Powders and aerosols, which can be very |
| This procedure is mostly straight forward, as an | | | | difficult to analyze, are discerned in this manner, and |
| emulsion of known or unknown particles in a known | | | | laser refraction and diffraction can be so precise that |
| liquid are slowly settled in a tube, and optical sensors | | | | individual nanometer-sized particles can be measured. |
| detect the sizes, shapes and settling velocities in a | | | | The Lorenz-Mie Theory is the rule by which the |
| matter of minutes. An excellent sedimentation | | | | calculations are made for the determination of particle |
| instrument can provide results in as fast as fifteen | | | | size and shape after the arbitrary light beam is |
| minutes. | | | | scattered when striking a spherical particle. It must |
| Sedimentation of the particles can reveal many | | | | be understood, however, that most particles in an |
| properties of the material being analyzed. The mass | | | | aerosol are particularly spherical, so this method must |
| of each particle can be determined by the velocity in | | | | also be used to determine shape. Many particles in |
| which the particles settle in the known liquid. Knowing | | | | powders maintain roughly the same size and shape, |
| the viscosity of the liquid in which the particles are | | | | depending on the material that is pulverized. Talc, for |
| suspended can give the analyzer calculation to the | | | | example, has different sizes, which can result in |
| particles mass, as gravity affects different masses in | | | | different properties of the powder. Since talcum is |
| a known solution. Emulsions of materials that are to | | | | used in many industrial methods, getting the right size |
| be analyzed that belong in the same state can be | | | | before fabrication of certain dependant materials is |
| separated into the different particles that make them | | | | crucial. Particle sizing instruments enable |
| up, thus giving an accurate physical attributes to the | | | | manufacturers to guide the quality of materials by |
| materials and how they behave after manufacturing. | | | | maintaining the proper particle sizes. |
| Paints that use specific pigments can be analyzed for | | | | Particle sizing is a crucial part of many material |
| quality control using this method, and it is also an | | | | manufacturing processes, and since there are many |
| invaluable tool for chemical engineers who design | | | | proven and reliable methods for analyzing particle |
| solutions and emulsions for many industries, including | | | | sizes, quality control is an area that has improved in |
| agriculture, pharmaceutical, and cosmetics. Pigments | | | | its own right. |