IDENTIFICATION OF THE STOCKS
It is important that a process machine operator be able to identify different stocks by their appearance in white light. The colour of the emulsion and the colour of the base or backing, if present, are useful for identifying film.
It is good practice to keep a sample of each film roll processed -just a few centimetres from the end of a roll, taken when the magazine is loaded, in order to check the type of film. A sample of each type of raw stock in use, mounted, one piece emulsion side up and one piece base side up, in a folder or on a card is a useful guide to compared with an unidentified stock.
Another approach to identifying unknown stock is to "dip test" a short length. Take a piece of film, dip it into a black and white developer for a couple of minutes, and then fix it in the dark. After a brief wash, it is usually possible to see the manufacturers edge codes, the presence of a backing, and whether there is any colour masking or anti-halation coating
