Notch codes: knowing sheet film by touch in the dark

Sheet film is loaded into holders in complete darkness, one sheet at a time, and it has two sides that look identical by touch except for one thing: a small pattern of notches cut into one edge. Those notches are the film's name and its orientation, readable with a fingertip.

What the notches tell you

Ilford's guide defines notch codes as indentations on the edge of a sheet that identify the orientation and the type of film ¹. Hold the sheet upright, in portrait orientation, with the notches at the top right-hand edge, and the emulsion is facing you ¹. That is the side that must face the lens when the sheet goes into the holder. Labs use the same notches to know how to process the film ¹.

Each film has its own pattern, so the notches also tell you which film you picked up if boxes have been mixed. Ilford uses two patterns for each product: one for sizes up to and including 5×7 inches and another for larger sheets ¹. Its guide shows the patterns for FP4 Plus, HP5 Plus, Delta 100 Professional and Ortho Copy Plus, and notes that its Direct Positive paper has no notch at all ¹.

Kodak's data sheets carry a notch code column beside each size and base too; on Portra 400 it reads "N/A" for 135 and 120, which have no notches, alongside the sheet-film entry ².

A routine for the dark

Before the lights go out, look up the maker's notch chart for the film in the box you are about to open. In the dark, take each sheet by its edges, find the notches with a fingertip, turn the sheet until they sit top right, and slide it into the holder with the emulsion toward the dark slide. A sheet loaded the wrong way round is exposed through its base: mirror-reversed, unsharp and usually useless, which is the best argument for the habit.

Try it

Take an old or spoiled sheet and practise with your eyes closed until finding the notch is automatic. Then keep the maker's notch guide ¹ with your holders.