Differing print values.

[Nabhar]

During a recent darkroom session, a friend produced two prints from the same negative. The exposure values were noticably different by somewhere between, at a guess, 1/3 - 1 stop. He claims to have processed the two prints identically, with one variation.....he loaded the second negative 'shiny side up', whereas the first exposure was 'shiny side down'.
I said that the 'turning' of the negative shouldn't affect the values, and that he had possibly given one print a touch longer immersion in the developer, due to the fact that we were nattering while we worked. But he said no, he didn't think so, and that the two prints received the same 'treatment'.
As a relative novice in the darkroom, I think that I called it correctly, but I would like to know for sure if the print exposure can be affected by this 'upside down' positioning of the loaded negative.....he would like to know too !
And.....Can an extra 30 seconds or so, in the developer (Ilford Multigrade 1+9), lower or raise the values by almost a full stop ?


Thanks
JP

[MartyNL]

In my opinion you're right. Turning the neg wouldn't affect exposure.

And 30secs would make a noticeable difference in print tone especially depending on your normal print dev time... which is?

[Steve Smith]

The light doesn't know which way up the negative is so I don't see why that would make a difference and prints are usually developed to completion. When I put a print in the developer, most of the development takes place in the first half to a third of the time. Thirty seconds more wouldn't make any noticeable difference to my prints.


Steve.

[Dave miller]

The negative orientation does not affect the exposure. The extra 30 seconds could however do so. Another possibility is that the developer was close to exhaustion.

[B&W Neil]

I would like to know for sure if the print exposure can be affected by this 'upside down' positioning of the loaded negative.....

Not in my experience :)

And.....Can an extra 30 seconds or so, in the developer (Ilford Multigrade 1+9), lower or raise the values by almost a full stop ?

It would depend if you are developing the print to its full extent in the developer. If you are an extra 30- secs would not make any difference. If you are not then yes you would notice a difference.

Neil.

[Richard Gould]

exposing the negative upside down would not make any difference at all, in fact, sometimes I, and no doubt others, will turn the negative to alter the composition, with no difference, as for 30 second extra development, providing you develop the paper to completion then 30 second should again not make any difference, the only other possibility that I can think of is the developer was nearing exhaustion, which would make a great difference,Richard

[JimW]

If your developement time is only say 60seconds-then an extra 30 seconds will make a difference. 60 seconds may not be enough time to develop fully your print, and so the extra 30 seconds will take the developement closer to completion.

[Richard L]

I once did a series of prints that were made up of 4 sheets of 5x4 film of the same subject - that is 4 sheets exposed one after another of the same thing, developed together, and then contact printed together so they formed a 10x8. This involved 2 sheets of film emulsion down, and 2 sheets emulsion up.
The sheets up varied in density visibly from the sheets down viewed on a print. I even swaped them around and got the same results. So even though it's difficult to know exactly why (and I dont) turning a neg over does alter printing time. Mot much, I reckoned on about 10% (for contacts).
Weird.

[RH Designs]

In the case of contacts, possibly diffusion effects through the film when emulsion side up?

[Nabhar]

Thanks for the replies.

We were sharing the same developer at the time, although I was using fibre-based, while he worked on probably a dozen or more 8x10 RC papers. Given that he processed the two prints in question toward the end of our 4 hour session, I think that I can assume from all the replies here that, the differing print values were a combination of him not paying enough attention to the time in the developer, and the depletion rate of the developer over the couple of hours we had already incurred. I was developing test strips and a few 8x10's, using 1min 30sec, and a few 2min immersions.
I'm not sure what times he was using but, I think we have pinned the answer down to his inattention (which I was 50% responsible for). :D
I'll now be extra careful myself next time I get chatting to someone in the darkroom, and consider this as, a lesson learned at someone elses expense. ;)

BTW...
I've informed him of this forum's existence, and I think we might have another addition to the ranks soon.

Thanks again guys
JP

[cliveh]

For practical purposes I also would have thought it would make no difference which way up it is, although from a physics standpoint, as one side of the film is shiny and the other not, in the shiny side up scenario it would reflect more light, thus reducing transmission. But it’s not something I would lose sleep over.

[Mike O'Pray]

My experience of Ilford MG dev for RC paper is that provided it has been developed for the recommended time of 1 min and isn't near exhaustion and is thus near completion, an extra 30 secs make only a marginal difference.

A good thing too as it is easy to get distracted and leave the print in the tray/slot for over the minute.

Mike