A field study on a series of emulsion-type sheep-branding fluids has elucidated the rôle played by various factors which, in practice, affect the scourability and legibility of such fluids, and has shown that, in the preparation and testing thereof, due account must be taken of the effect of the type of wool on which the brand is put, the effect of time upon scourability and legibility, and the type of scouring solution used.