View Full Version : Maximum exposure times for fiber based papers?

22-Sep-2006, 10:25
Does anyone have any pointers as to which fiber based papers have extended exposure times. For example Forte polygrade specs state a max of 2 minutes, which is fine if just printing with "normal" times and you can then get the print straight into the developer bath. I have about 5 minutes of enlarger and safe light before I get the fully exposed papers into the dev! I am thinking of dropping the safe light and working in blackout mode, haven't tried this yet I am just thought maybe it might extend the "fogging times? :D

Ole Tjugen
22-Sep-2006, 11:38
I haven't had any problems with any paper when lith printing, exposure times up to at least half an hour. Of course a thorough long-time safelight test is a good idea before attempting this.

22-Sep-2006, 12:44
Are you referring to the actual exposure from the enlarger or the safelight exposure?

I use Ilford Multi-grade fiber base paper for all of my prints. I do a lot of large prints from 24x30 to 38x40 and my exposure time with dodging and burning steps can run up to 10 minutes. This is in addition to the time it takes for cutting the sheets from the roll. I have tested my safe lights to 15 minutes and there is no problem there. I do turn the safe lights off on the dry side during the exposure but that is more to aid dodging and burning.


22-Sep-2006, 12:48
I try not to let paper get old, but sometimes it happens (I have about 1/3 of a roll of 42” paper now that went south) and as it gets older it seams to be more susceptible to fog.


Brian Ellis
22-Sep-2006, 13:50
There's a big difference between exposure by enlarger light vs "exposure" by safe light. Time under the safelight is image forming light. While you might run into reciprocity failure with lengthy exposure times, that's about the worst that can happen as a result of long times under the enlarger light. Safelight time is non-image forming light, it simply adds undifferentiated and unwanted density to the paper. So it's the safelight with which you need to be concerned, not the exposure time under the enlarger light.

You need to conduct a proper safelight test if you haven't done so already. Kodak used to have a description of how to run a proper test on its web site. There's another version found in Ansel Adams' book "The Print" and I'm sure in many other places as well.

I could certainly be wrong, I've never used Forte paper, but I doubt that their two minute time refers to the total time for which the paper can be exposed to a safelight because that obviously varies with the particular type of safelight, its strength, where it's located, etc. If you want to pursue this you might post a quote of exactly what the Forte instructions say about two minutes.

Brian Ellis
22-Sep-2006, 13:53
Correction - the second sentence should read "Time under the ENLARGER light is image forming light," not time under the safelight is image forming light. Sorry.

23-Sep-2006, 07:37
I've now posted another post with reference to this point
See yal over there..