my prints have a hazy psychedelic mottled surface. Someone told me it is because I have them in the developer for only a few seconds and they need to be in for 30 seconds, but then they would get too dark. Should I dilute the developer more or close down my aperture or decrease my exposure?


It takes time for development to come to completion. If you pull the print out of the developer too quickly, you will get a blemished that is dappled, we call it blotchy. As a rule of thumb, print development time averages about 90 seconds. Some developers are more energetic yielding a developing time of 60 seconds. Others are sluggish with a developing time of 120 seconds. Time in solution is a variable based on temperature and chemical strength. I often told my students to plop the print into the developer upside-down and wait 90 seconds before turning them over for viewing. This way, they quickly got it, you must adjust the enlarger exposure time so that the prints develop up within the recommended time span = 60 to 120 seconds.

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  • Thank you so much. I have had my students putting them in for only a few seconds. I am a painter who has to teach darkroom as part of my job and I really appreciate your wisdom and suggestion to put the prints in upside down. – Jill Callahan Apr 27 '17 at 17:53
  • Since you are a novice as to teaching this subject – some added tips: Do use a stop bath after the developing step. This is a mild acid (vinegar) solution. Its job is to stop developing fast plus it prepares the print paper for the next step which is the fixer. Since a mild acid is a chief ingredient of the fixer, the stop bath prolongs the life of the fixer by neutralizing the alkaline developer that otherwise would rid piggyback into the fix and contaminate it. Next, make sure the prints are fully washed to rid them of residual chemicals that stain. Best of luck – Alan Marcus Apr 27 '17 at 18:55

Without seeing the print, it sounds like uneven development resulting from a very short development time. What's your developer and paper, and what are the recommended dilutions and times? Most print developers have a one to two minute development time at the recommended dilution.

If your source image is underexposed, you would control this not by decreasing your print development time but rather by using shorter print times and/or stopping down (at the enlarger). It could be that it's so underexposed that a well exposed print is unattainable in the darkroom.

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  • This issue is occuring in a classroom setting with many kids. I mixed the Ilford developer at 9:1 so I think it has to do with the enlarger aperature choice. – Jill Callahan Apr 27 '17 at 17:55
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    @JillCallahan - You should read about creating a test strip. Basically, choose one aperture (say f/8) and expose a sheet of paper for, say, three seconds. Cover part of the paper, and expose for another three seconds. Continue until you have a range of timed exposures on the paper (like 3 to 18 seconds). Then pick the time that shows the best exposure to make your final print. Your developer is fine. Continue to use 1:9 and always develop for at least one minute or as instructed. – bvy Apr 27 '17 at 18:54

If you need to pull your print from developer before it gets too dark then you are overexposing it. It will look no good; prints are supposed to be developed till completion.

Dilution of the developer is not the problem, provided you did stick to the manufacturer recommended dilution.

You need to close the aperture and/or shorten your time. Or some combination of both - remember that 1 step of aperture means doubling (halving) your exposure time.

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  • Thank you Jindra, do you mean that when I close the aperture a stop down I halve the time/exposure and if I am opening it I double the time/exposure? Intellectually this seems like the same thing to me but maybe in physical reality it's not. – Jill Callahan Apr 27 '17 at 17:58
  • I meant that these two things are equivalent; to decrease your exposure by 1 unit you have to either halve your time (e.g. from 10 seconds to 5) or increase your f stop (e.g. from 4 to 5.6). In reality it is impractical to work with very short (<5 seconds) nor very long (>30 seconds) times. You also do not want your lens fully open (you would run into sharpness issues) nor too closed (when diffraction kicks in). The "correct" time also depends on your paper size (or head elevation) and how powerful is your light source. It sounds difficult, but it is not :) A notebook is your best friend. – Jindra Lacko Apr 27 '17 at 18:10

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