Polaroid Type 55
film is a black-and-white peel-apart Polaroid
film that yields both a positive print and a negative image (which can be used in an enlarger). Though box-rated at 50 ISO
, the positive and negative parts of the film are effectively rated at 50 and 35 , respectively. It is possible, however, to rate the negative at 32 ISO. Polaroid rates the negative at 25 ISO. When processed and peeled apart, the positive needs a protective coating, included in the box of film, to keep it from fading and the negative needs to be cleared in a hypo-removing solution (Kodak's Hypo-Clear works). Polaroid recommends an 18% Sodium-Sulfite solution. Polaroid also recommends using a hardening fixer to further protect the negative from scratches, but allows that it is not mandatory. The reason for this is that Type 55 negatives are very thin compared to other 4x5" negatives, and the emulsion is extremely soft.
Type 55 negatives are fine grained, have a long tonal range and are of extremely high resolution, around 150 lp/mm. They are useful for making large prints and for contact printing, especially in alternative processes such as Cyanotype
and Van dyke brown
Type 55 negatives are the famous source of the "Polaroid frame look". Due to the development process where a Polaroid 545 film back holds the film for exposure with a Large format
camera, the Polaroid reagent/gel is squeezed between the negative and positive. Some of the reagent is trapped underneath the... Read More