Glassflake is produced to a range of nominal thicknesses and particle size diameters. Both the absolute thickness and deviation of thickness play an important role, as large variance can result in an inconsistent visual effect - by producing glassflake with a very narrow distribution of thicknesses, the overall thickness of the metal oxide coated flakes remains consistent, enhancing the pearlescent effect. Given the importance of consistency in glassflake thickness, this is measured by two methods, both SEM and spectroscopic analysis. Glassflake is offered in 3 nominal particle size distributions (nmilled, milled and micronised), each of which is measured by laser diffraction. In addition to these standard particle diameter distributions, we can work with customers to provide specified particle diameter distributions, to produce a 'Reactor Ready' grade, removing any requirements for excess customer processing.
Glassflake composition has a vital role to play in core areas such as: the harsh processing of coating with metal oxides; meeting strict regulatory requirements for the food and cosmetic markets; and maintaining surface chemistry suitable to accept metal or metal oxide coatings. Glassflake test the heavy metal content of glassflake both externally and internally by ICP-OES and ICP-MS, using complete dissolution by hydrofluoric acid with microwave assistance.
Using thinner glassflake platelets as substrate for metal oxide coatings offers particles of higher aspect ratio. Where thinner glassflake substrate is used, diameters can be reduced to produce pigments suitable for use in high gloss systems, with pearlescent effects at lower loading levels.