Mica flakes classification
Natural mica can be transformed into coarse, medium and fine varieties of flakes and powder by the process of pulverization and thereby it renders itself to wide commercial applications in these forms.
The table presented below is showing some applications of flakes of mica or ground mica depending on the degree of fragmentation.
Applications by the size of flakes
|Coarse Flakes||3,36||6 Mesh||oil well drilling||overcome lost circulation, as a mud additive|
|pearlescent pigments||to provide pearly luster in paints and other articles|
|artificial snow||as snow substitute|
|Medium Coarse Flakes||1,68||10 Mesh||Christmas ornaments and display materials||as flocking material and to provide glittering effects|
|Fine Coarse Flakes||1,0||16 Mesh||concrete block fillers, refractory bricks, gypsum boards, slabs, tiles||reinforced structures provide thermal insulation, fire resistance, sound absorption, corrosion protection|
|asphalt roofing felts, shingles||as a protective coating and provides weather-proofing|
|Coarse Fine Powder||0,55||30 Mesh||explosives and disinfectant||as a filler or an absorbent|
|automotive components||as soundproofing mats and pastes|
|Medium Fine Powder||0,25||60 Mesh||welding electrodes, cables and wires||as protective coatings and improves dielectric properties, electrical and mechanical strength|
|foundry works, pipeline, enamels, mastics, body lubricants, adhesive||improves physical properties, anti-sag, reduce cracking|
|Fine Powder||0,15||100 Mesh||texture paints
|improves physical properties, architectural durability. adhesion. water proofing|
|Superfine Powder||0,04||325 Mesh||paints||improves exterior durability, increase moisture resistance, flexibility, adhesion, etc.|
|plastics||improves thermal and dielectric properties, impact strength, imparts heat resistance|
|rubber products including automotive tyres||prevents adhesion of rubber compound to the cores and outer sheaths during vulcanization|
|paper||provides stiffness, lower density and higher permeability|
|cosmetics||powders and fluids|
The process of sorting flakes and powder (ground mica) into individual fractions is carried out using sieves of different mesh sizes.
Commercially, as a criterion of the flakes size the number of screen or mesh-scale are used, often millimeters or inches are used. Below is shown a table that allows you to convert various size scales of mica flakes.
Table For Screen Sizes
|Sieve no.||Mesh Size||Microns||Mm||Mils||Inches|
What does mesh size mean?
Figuring out mesh sizes is simple. All you do is count the number of openings in one inch of screen (the number of openings in a lineal inch measured from the center of one wire to a point one inch distant). The number of openings is the mesh size. So a 4-mesh screen means there are four little squares across one linear inch of screen (see fig.). As the number describing the mesh size increases, the size of the particles decreases. Higher numbers equal finer material. Mesh size is not a precise measurement of particle size.
What do the minus (-) and plus (+) plus signs mean when describing mesh sizes?
Here's the explanation:
- -200 mesh means that you need all particles that pass through a 200 mesh,
- +200 mesh means, that you need all particles that remain on the sieve of 200 mesh.
If you needed a ground mica that was closer to size you would need to specify two mesh sizes. For example: ground mica -40+100 Mesh. This mica powder would have particles that were smaller than 40 mesh (420 micron) but larger than 100 Mesh (149 micron). The customer receives a powder having a particle passed through the 40 mesh screen but was trapped in the 100 mesh screen. Rejected are larger particles (were trapped above in the 40 mesh screen) and smaller particles (passed through the 100 mesh screen).
How fine do screens get?
That depends on the wire thickness. If you think about it, the finer the weave, the closer the wires get together, eventually leaving no space between them at all. For this reason, beyond 325-mesh particle size is usually described in “microns.”
While every attempt has been made to verify the source of the information, no responsibility is accepted for accuracy of data.