Ilford 12 x12" Multigrade Printing Filters are used for printing the Ilford Multigrade range of papers on black-and-white enlargers. Ilford produces complete sets of filters for all contrast grades in half grade steps.
The twelve multigrade filters are in sets and are numbered 00-5 in .5 steps. The lowest number corresponds to the softest contrast.
Multigrade filters are supplied in 3, 6 and 12" square sizes to fit most enlarger's filter drawers, or as a set of mounted hard plastic filters for below-lens use in a filter holder.
Multigrade filters do not require any recalculation of exposure times when changing between grades 0 and 3, grades 4 to 5 simply requiring twice the exposure.
Easy way to control print contrast using variable contrast paper
Exposure time for filters 00-3.5 is the same; that for filters 4-5 is double