Stains on prints

[Pieter12]

Lately I have seen some small, straw-yellow stains on the edge of some of my prints. Obviously not detectable under safelight, but I am surprised when I turn on the white inspection light. I am pretty careful about rinsing my fingers and tools between solutions and wonder if anyone can tell me which solution is causing the stain, based on the color. I would think if it is developer and stop bath, the stain would be more purple-brown because of the indicator in the stop bath. Should I attempt a quick dip in clean water between the stop and fix?

 

[MattKing]

Which paper?
The indicator itself doesn't seem to stain prints.
But if the stop bath hasn't been given enough chance to fully neutralize the developer, and significant amounts of developer imbued emulsion makes its way into the fixer, that can cause staining.

 

[Pieter12]

Ilford MGFB glossy. The developer is EcoPro, as is the fixer. Stop bath is Stop Block. I have been using this combination for many years now with no problem. I also have been using the same times: developer 3 minutes, stop 30 seconds, fix 2 minutes. All dilutions are per the manufacturers' data sheets. The only thing that may have changed is right now the darkroom is about 5-10ºF hotter than usual.

 

[MattKing]

It may be related to the temperature. That may affect how much developer is absorbed by the paper.
Try extending the stop bath time, making sure that there is sufficient agitation during that step.

 

[NB23]

Stain is always related to developer being carried into the fixer. In other words: not fully stopped.

Also, stains in the toner are always caused by fixer being carried into the toner. In other words: not fully rinsed.

 

[Pieter12]

Stain is always related to developer being carried into the fixer. In other words: not fully stopped.

Also, stains in the toner are always caused by fixer being carried into the toner. In other words: not fully rinsed.

Thanks. Guess if I want to save those prints, I could always bleach the stained area. It is small (maybe 3/8"x3/4") and only in the white border.

 

[snusmumriken]

I learned early on that fixer sticks eagerly to skin eagerly and is difficult to rinse off, but perversely is easy to transfer to onto printing paper (and everything else you touch). So now I always use tongs, colour-coded for the different solutions. However, I think it would be obvious to you if your stains occurred where your fingers go.

Then, at there risk of stating the blooming obvious, whatever makes the stains in your prints shouldn't be there. So either you aren't giving the paper long enough in the stop bath, or you aren't replacing the fixer often enough, or you aren't washing for long enough. The action of the stop bath in the emulsion takes a matter of seconds. But FB paper is completely saturated with developer when you transfer it to the stop bath, and it takes longer for the stop bath to get into the fibre base and neutralise it. So although the indicator may show that your stop bath is not exhausted, it may not have penetrated deep enough to prevent carry over of developer into the fixer, where it will react. I give FB paper at least a minute in the stop bath, with continuous agitation.

It's also a good move to use two fixer baths, both because it's more efficient and because it helps prevent stains. Bath 1 is discarded after each session and replaced by Bath 2. Bath 2 is mixed fresh for each session. I forget the exact chemistry, but the principle is that waste products formed in fixer Bath 1 through developer carry-over (and through actual fixing) are removed by the fresher fixer in Bath 2. Ilford recommends 1 minute total fix time for FB paper in their Rapid Fix, but actually I find this isn't enough to prevent staining when I selenium-tone the prints: so I give 1 min in each bath, and again I rock the dish continuously.

You can buy a test kit to check for residual fixer after the prints are washed, which is worthwhile if considering longevity of the print, But I think you are saying that the stains are visible before washing(?), and anyway as you can already see stains it seems superfluous to test for fixer residue. Better to clean up your process to minimise the load of unwanted waste products in each bath!

 

[Pieter12]

Therin lies the rub. I use a Nova Vertical slot processor, and the only thing touching the prints are my fingertips along the short edge for 11x14" prints, and the print clip that holds the paper during the entire time in the processor. I learned to thoroughly rinse my fingers between steps to prevent carry-over. However, it seems enough stop bath is not getting into a small area inside the clip (there is a gap between the clip and the paper--the paper is actually held in place by two sharp pins). Although the levels in the slots look like they are covering the paper, because the stop bath time is so short (it's only in there for 20 seconds, then lifted out and allowed to drain back for the last 10 seconds), that particular area is obviously not getting enough exposure to the stop bath. I will see how high I can fill it without risking splashing into the adjacent slots and maybe leave it without agitation for an additional 10 or 20 seconds.

 

[logan2z]

Therin lies the rub. I use a Nova Vertical slot processor, and the only thing touching the prints are my fingertips along the short edge for 11x14" prints, and the print clip that holds the paper during the entire time in the processor. I learned to thoroughly rinse my fingers between steps to prevent carry-over. However, it seems enough stop bath is not getting into a small area inside the clip (there is a gap between the clip and the paper--the paper is actually held in place by two sharp pins). Although the levels in the slots look like they are covering the paper, because the stop bath time is so short (it's only in there for 20 seconds, then lifted out and allowed to drain back for the last 10 seconds), that particular area is obviously not getting enough exposure to the stop bath. I will see how high I can fill it without risking splashing into the adjacent slots and maybe leave it without agitation for an additional 10 or 20 seconds.

Make sure you thoroughly rinse the clips between prints. I occasionally had yellow staining appear on the border of my prints when I didn't completely rinse off the clip after making a print.

Also, be careful not to overfill the slots of the processor. A couple of times I filled the slots with too much fluid and the pressure of the fluid against the slot dividers caused them to flex which raised the fluid level in an adjacent slot and caused an overflow.

 

[pentaxuser]

I have only ever used a Nova for printing and it's the 8x10 model. I have never experienced Pieter12's problem but this may be because I have a separate Nova slot washer at the end a that's connected to running water so the clip is immersed in running water for about 1-1.5 mins

Certainly you need to ensure that the clips are flushed through by some means or the nature of them means that they could harbour remnants of fix but the sequence of slots should ensure that any developer is killed by the stop slot and any stop is killed by the fix slot

pentaxuser

 

[Sirius Glass]

Stain is always related to developer being carried into the fixer. In other words: not fully stopped.

Also, stains in the toner are always caused by fixer being carried into the toner. In other words: not fully rinsed.

Yes, but so many here claim that stop bath is just so damned expensive! They claim that if they use stop bath that they will must have to give up using film and then go off to buy their double creamed pumpkin spiced lattes with extra shots a $tarBuck$ three or four times a day.

 

[Pieter12]

I have only ever used a Nova for printing and it's the 8x10 model. I have never experienced Pieter12's problem but this may be because I have a separate Nova slot washer at the end a that's connected to running water so the clip is immersed in running water for about 1-1.5 mins

Certainly you need to ensure that the clips are flushed through by some means or the nature of them means that they could harbour remnants of fix but the sequence of slots should ensure that any developer is killed by the stop slot and any stop is killed by the fix slot

pentaxuser

Thanks. I do rinse the clip between prints, maybe I should do it more thoroughly. But the problem appears to be developer making its way through the stop bath and fix. Unless I can devise a method of changing out the clip between the developer and stop stages I’ll have to be extra careful to make sure the area under the clip gets fully stopped.