Ultimate ParticlesPhysical particles of materials are those we can measure using ordinary sieves. Using water washing and standard wire mesh sieves it is normally only possible to determine the range of particle sizes of a powder sample down to 325 mesh (about 40 microns). However the particles measured by this means are agglomerates of hundreds or even thousands of ultimate particles. However in ceramics, we are dealing with ultimate particles far smaller than this in almost all materials. Ball clays, for example, have particles one tenth of a micron in size, 400 times smaller than 325 mesh. It is common for +95% of many materials to pass a 325 screen. Understanding materials fully means being aware of these particles, their sizes, shapes, densities, etc. To effectively measure ultimate particle sizes advanced testing equipment is needed. These devices use xray or photographic techniques. For example, many devices simply take a micro photograph of an air suspended powder sample and then software analyzes the photo to produce the desired measurement.In Bound Links
UnderglazeOxide color mixtures which are applied to bisque or green ware and over which a transparent glaze is applied. To prevent excessive feathering of edges, underglazes are usually a mix of metallic oxides and a fritted stable glaze.Unity FormulaA unity formula is just a formula that has been retotalled so that the RO group of oxides total one. This is also called a Seger formula and this standard provides the basis for comparing glazes.Out Bound Links
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