Polaroid Type 31

Type 31 sat in the slower half of Polaroid's Series 30 roll film line, the 2.5 by 3.25 inch picture format that fed the Highlander and the small-frame Land cameras of the mid-to-late 1950s. At ISO 100 it was the slow-speed companion to the faster Series 30 stocks, used by photographers who wanted finer grain and tighter tonal control than the high-speed rolls could give them. The pictures came out smaller than the 3.25 by 4.25 inch prints from the Series 40 lineup, which kept the cameras lighter and the film cheaper per shot.

Development ran about 10 seconds at room temperature. The print pulled out with a sepia-warm midrange that read closer to traditional silver work than to the cooler tones of later coaterless emulsions. Like every Polaroid roll film of this generation, the print needed a protective coating swab applied after peeling. Skip the coating and the image yellowed inside a few months. Boxes shipped with a small tube of pink coater and a wand.

The Series 30 cameras were aimed at hobbyists and family use rather than the press market that drove Series 40 sales. Type 31 was the version you loaded for snapshots in good light where Type 37 at ISO 3000 would have been overkill. Compared with the contemporary Type 42 in 3.25 by 4.25 format, Type 31 gave slightly finer grain but a smaller print that did not scale up well past contact-sheet size.

Type 31 itself ended in 1958. The wider Series 30 roll format limped on with Types 32 and 37 until 1979, when Polaroid discontinued the remaining roll films across the line. The cameras were already two decades out of production. Today the rolls only turn up in estate sales of working photographers from the Land era, and the chemistry has long since failed in any pack stored at room temperature.

Reciprocity exponent is 1.0. Zone Light Meter applies the long-exposure calculation past one second, but on Type 31 the correction is zero. A metered 2-second exposure stays at 2 seconds at the print. The Series 30 cameras had limited shutter ranges anyway, so reciprocity was rarely the constraint that mattered.