Polaroid type 55

Infobox Photographic film
name = Type 55
maker = Polaroid
speed = 50/18° ("pos") 35/16° ("neg")
bw = yes
format = 4×5"
type = i
app = General

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. There are some photographers who 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. Some photographers prefer to put the negative in a hardening fixer, though not all feel it necessary. 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 contains the film for exposure with a camera like a large format Graflex Speed Graphic or Cambo, the Polaroid reagent/gel is squeezed between the negative and positive. Some of the reagent is trapped underneath the onion-skin-like frame that crops the print into a perfect 4x5 image. This reagent however creates an impression of that frame on the negative, which is not protected. The result is a perfect negative, but with imperfect frame-like image surrounded 3 of the four sides, while the 4th side shows the impression of the connective mesh that controls aspects of the Polaroid packet's sleeve functionality. This "Polaroid frame look" has been used extensively by many photographers who don't actually shoot large format, let alone Polaroid Type 55, but will scan a Type 55 negative in and superimpose the frame onto their other digital or scanned photos.

Polaroid Type 55, like all Type 50 series film, requires a Polaroid model 545 film packet Back. This Back is a device that loads the packet of sleeved Polaroid film sheet onto the back of a camera, most often a large format 4x5 inch camera. The same device is used to develop the film once its removed, simply by pulling a lever into another direction and pulling the entire film packet out.

In February 2008, Polaroid announced it would cease production of all instant film, including type 55.

External links

* [http://www.polaroid.com/global/detail.jsp?PRODUCT%3C%3Eprd_id=845524441760052&FOLDER%3C%3Efolder_id=282574488338434&bmUID=1181368136656&bmLocale=en_US Polaroid: 55 film]
* [http://www.polaroid.com/service/filmdatasheets/4_5/55fds.pdf Polaroid datasheet]
* [http://www.flickr.com/groups/polaroid55/pool/ Polaroid 55 pool] on flickr.com.