These grids are electro-formed which results in particularly clean edges. The high grade grids have thinner bars and greater openings. Au grids are available on indent. .
Nylon contains a small amount of titanium.
Butvar films are the strongest plastic support films. They stabilise quickly under the electron beam and require no carbon coating. Butvar has very little structure and is suitable for high powers of negatively stained specimens. Formvar coated grids are stabilised with a thin carbon coating. Self supporting carbon films have the least structure and may be required for the most demanding specimens.