Edge markings

Edge marking density generally means nothing. Maybe it did way back in the day when companies like Kodak were VERY diligent about the tiniest detail. It's just not a reliable yardstick of development. Back then you could shoot a roll of film and let it sit in the camera for 40 years and the image would still be there. These days, not so much. This post is strictly an opinion.

They never have been a consistently reliable indicator. They are due to controlled light exposure at the time of manufacture, so all the factors that can affect latent image retention like age, storage conditions, handling, nature of emulsion, presence or absence of backing paper, can all result in variability.
It was that way during the heyday of film - Kodak, Ilford, Fuji, 3M et al - and it is that way now. The only real differences between then and now is that modern film tends to experience more variability in conditions before it gets into the hands of the consumer.

If you have two within date films from the same batch or bulk roll that you have had in your possession since you bought them new from a retailer, and you have stored them in identical conditions, and have subjected them to similar conditions up to and after exposure, and then you develop them similarly, then, and only then, can you expect consistency.

We just had a long thread about just this: https://www.photrio.com/forum/threads/fp4-edge-info-very-light.214909/#post-2914452

Edgeprint for long roll and 35mm films from Kodak which would read something like "Eastman Safety Film", prior to the introduction of computer and LED systems, were applied with a bulb system that had two to three settings for power. Thus, as film speeds increased, edgeprint density would vary depending on the selection of the setting used (one of the settings had to be super strong for the Color Print theater film with an ASA of about 1.5-2) so the densities for film codes from ASA 32 up to 1000 would vary greatly.

Frame marking edgeprint for 135, sheet film, and 120 was better controlled in the early days as each product's stenciling pattern / identification was made onto a belt of graphic arts film and the light passing through was filtered to achieve a consistent density, the filters being different for each film speed.

With the introduction of LED and laser printing, more exact densities have been achieved, so in the past twenty to thirty years, densities should be much more consistent across the film codes.

Melvin J Bramley said:

Are film edge markings indicative of correct film development?
Are weak edge markings the result of under development etc?

Click to expand...

No.