What do the numbers on the left of this Kodak Vericolor film reel mean?

Question

Kodak film reel found still sealed what do the numbers mean on the left

Answer 1

6011 is the product number. This designates it as Vericolor Internegative Film, which is also printed out on the label. It was made to be processed by conventional C-41 chemistry. ECN-2 chemistry could also be used to develop it.

36-54 appears to be a batch number. Kodak introduced 6011 in 1978. The expiration date was around 20 months after manufacture, so your roll of 6011 that expired in August 1981 would have been made right around the end of 1979 or the beginning of 1980. That's less than two years after Kodak started making 6011. By the mid-1990s, batch numbers had grown from two two-digit numbers to two four-digit numbers, such as 3361-0122.

Internegative film was used to create negatives from positive color transparencies (either "slides" or larger transparencies) or color prints. It is balanced for 3200K enlarger lamps.

It is very slow. When fresh it would have probably been around ISO 6. Yes, that's ISO 6, not DIN 6. This Flickr thread discusses 6011 and ISO. In 2014 the user tested two rolls. One from 1980 (34 years out of date) tested at ISO 0.75, one from 1994 (20 years out of date) was ISO 1.5. The user did not reveal under what conditions either had been stored for that long.

Answer 2

These are “batch numbers”. Each batch is unique. In other words, there are slight differences between how the film will react to light, between batches. These are internal numbers used to identity this particular batch. This is a roll of “Inter-Negative” film. It has two main uses:

1. To make color negatives from transparency (slide) film. In that era, photographers often loaded their cameras with slide film. Slide film is “direct positive” film. Upon developing, the results were slides that were shown by projecting each on a screen much like you see at a movie theater. Often, instead of a slide, a color print on paper was desired. We loaded a special camera with “Inter-negative” film and made a copy of the slide. When the “inter-negative” film was developed, the result was a color negative that could be used to make color prints. Making an inter-negative from the slide was the preferred way to obtain a print, because inter-negative film allowed for lots of adjustments as to the color balance and contrast of the resulting print.

2. Copy prints are duplicate prints made from an existing color paper print. Often the owner of a color print did not have the original color negative that made their color print. A copy negative was made by taking a picture of the color print using a camera loaded with “inter-negative” film. The resulting color negative was used to make a copy print.