Frit

A finely ground glass material which contains small amounts of one or more micro-nutrients. A micronutrient source is added to sodium silicate (liquid glass) in the manufacturing process and heated to a very high temperature (about 100C, or so) to produce a molten material; this is then rapidly cooled and shatters into very fine fragments and then ground into a powder like material ready for application to plants. Also known as FTE: Fritted Trace Element/s.