Brandt C R, Davis R
J Microsc. 1978 Jul;113(2):145-7. doi: 10.1111/j.1365-2818.1978.tb02457.x.
An improved technique has been developed to produce a positive image directly on some standard electron microscope films (Kodak 4489, SO 163, and Ilford Electron Microscope Film). This technique has been useful for processing micrographs of freeze-etched and shadowed specimens, and eliminates the need for producing positive image transparencies before printing.