Developing gevapan 33

I shot a rol of Gevapan 33 from 1967. I shot it at 100 iso and planned to push it when developing. I read online that the original developing time was 10 mins with D76. Should I push it to 20 mins?

Likely this film will have a high amount of fog. D76 might not be the best choice. Kodak's HC110 and Ilford's Microphen might show less fog. Also processing at a lower temperature (65 degrees vs 68 degrees might help). If all you have as D76 by all means do give it a try. Increasing time to 20' might increase the fog more than image.

As well as I know, the original ASA is close to 100, maybe 125, so 100 should be about right.

 

At some point, overdeveloping develops fog as fast or faster than image.

 

A little more might be fine, but 20 minutes sounds like a lot.

Maybe 12 isn't so much, though, but I probably would do the recommended 10.

I'm going to suggest 12 to 15 minutes. More than about 20% has the possibility to add to your problems, not limit them. Depending on the subject that you shot, a clip test might be in order. Cut what should be one or two frames from the roll, process and fix that. Use what you get there to determine your next move.

 

I don't recall ever SHOOTING old film but I have developed a lot of it found in used cameras over the years.