Iron Hydroxide Stain? Pt Pd

[Solarize]

I’m using Rubylith around my negatives so I can print clean borders with platinum/palladium. After developing (in Potassium Oxalate) and clearing there is a marked grey stain in the unexposed borders. Could this be Iron Hydroxide stain? My Ferric Oxalate is always mixed fresh before printing, and the developer kept on the acid side. I'm going into an acid clear after developing.

Outside of using the developer ‘one-shot’, is there something else I can do? The grey is not visible on the image itself, only the borders, but it’s bothersome. It is worst in areas where there is an excess of coating solution that has absorbed into the paper and needs to be cleared.

Currently I'm masking the coating area with tape, which although time consuming eradicates the problem. On larger prints however I want to coat with glass rod, but the tape lifts it off the paper surface making that unworkable.

I would be very grateful for any suggestions on how I can avoid the grey.

 

[Gerald C Koch]

No, the color dos not match that of any iron hydroxide. Ferrous hydroxide is a white precipitate when first formed but soon changes to green on exposure to oxygen. Ferric hydroxide does not exist. What is formed is a reddish brown solid of hydrated ferric oxide.

I would suspect that the gray color is from finely divided platinum or palladium. The equivalent of fog in a silver emulsion.

 

[jeffreyg]

About three years ago I was printing a limited edition series for another photographer and had a similar problem. I ended up masking with mat board and a mask with rubylith that I attached to glass of the printing frame with black masking tape. I was told by Bostick and Sullivan as mentioned by Gerald that it was free pt/pd getting into the texture of the paper. After developing with ammonium citrate I put the prints on an acrylic sheet and hosed them off and placed them emulsion down in the EDTA baths. I also washe with the emulsion down. Gravity seems to be helpful. That stopped the problem.

Actually, I like the coated borders which can either be shown or covered with a mat

http://www.jeffreyglasser.com/

 

[Ian Leake]

I agree with Gerald. It could be lack of clearing but is most likely to be fog. Try reducing the ambient light when coating and drying, or adding a bit of restrainer. You may also get better results by masking the area to be coated with tape so you only get sensitiser where you want the image to form. This means you have to carefully align the negative but it generally looks better.

 

[Solarize]

Thank you for the contributions. As an experiment I completed the whole process in the darkest of conditions, but still had the same problems. Besides masking the coating area, the only thing that seems to have reliably circumvented the issue, is the use of fresh potassium oxalate. Could this make sense chemically if the problem is fog? Or perhaps I've misattributed the problem....

I can rule out improper clearing and light. If it's not the developer, and my ferric oxalate is fresh, I think I should look next at heat and humidity. The dimroom is in a poorly insulated loft conversion, so I do struggle to maintain consistency with temperature and humidity. Fluctuations might explain the varying degrees of fog in the borders. One thing I do know for sure, is the flaw is most obvious in areas where there has been a greater build up of solution during coating - the very edges and corners in particular.

Ian, I'm using ferric oxalate without any restrainer, controlling contrast with negative and developer grade instead. Would prefer to continue like I am, but this could be an option to test. The washi tape you mentioned on your blog in the past is excellent, so hat tip for that. It's purely the added time and difficulty in rod coating that has me keen to rubylith the negative edges instead.

 

[Gerald C Koch]

Besides light fog there is also chemical fog. Something is causing the over-all non-image reduction of the Pt/Pd salt. Are you using a recommended brand of paper. Your problem could be caused by something in an unapproved paper.

 

[pdeeh]

T. The washi tape you mentioned on your blog in the past is excellent, so hat tip for that. .

is that tape self-adhesive or gummed?

 

[Solarize]

Gerald, I'm using COT-320 and occasionally Herschel from the Ruscombe Mill - both recommended for the process. I have the same problems with both unfortunately. The thing I find most odd is that there is no perceptible fog within the image where I get paper white. It's only the non-exposed areas, basically on the very edges of the coating.

Pdeeh, the brand is MT Foto and RK Photographic carry it in the UK. The adhesive is strong enough that no coating solution gets under it, but it also peels away from the paper without causing damage or leaving residue.

 

[pdeeh]

Yep I followed the links, it just didn't say anywhere whether sa or gummed. But sounds like sa

 

[Solarize]

Yep, self adhesive.

 

[pdeeh]

ta

 

[Ian Leake]

Thank you for the contributions. As an experiment I completed the whole process in the darkest of conditions, but still had the same problems. Besides masking the coating area, the only thing that seems to have reliably circumvented the issue, is the use of fresh potassium oxalate. Could this make sense chemically if the problem is fog? Or perhaps I've misattributed the problem....

I can rule out improper clearing and light. If it's not the developer, and my ferric oxalate is fresh, I think I should look next at heat and humidity. The dimroom is in a poorly insulated loft conversion, so I do struggle to maintain consistency with temperature and humidity. Fluctuations might explain the varying degrees of fog in the borders. One thing I do know for sure, is the flaw is most obvious in areas where there has been a greater build up of solution during coating - the very edges and corners in particular.

I've seen exactly what you're describing (I think) - a thin line around the edge of the coated area. I never did actually work out a solution, and it went away when rI started masking with tape. I think what is happening is that the rubylith doesn't entirely block the UV during long exposures so the coated area gets a small exposure. This affects areas of sensitiser with greater moisture content more than others (e.g. The very edge). I've never tested this theory but it would be easy to test by placing a piece of tin foil under the rubylith to ensure absolutely no exposure.

It's possibly related to developer but I think unlikely because this effect is only seen in parts of the coated paper that were not covered by the negative.

Ian, I'm using ferric oxalate without any restrainer, controlling contrast with negative and developer grade instead. Would prefer to continue like I am, but this could be an option to test. The washi tape you mentioned on your blog in the past is excellent, so hat tip for that. It's purely the added time and difficulty in rod coating that has me keen to rubylith the negative edges instead.

I use 'restrainer' in it's broadest sense. The dichromate in the developer is a restrainer. You can also put restrainers in the sensitiser but that is less than ideal IMO.

I'm glad you like the washi tape. Sadly I can't find any in Switzerland so I have to order it from the UK :-(

 

[Solarize]

I think what is happening is that the rubylith doesn't entirely block the UV during long exposures so the coated area gets a small exposure. This affects areas of sensitiser with greater moisture content more than others (e.g. The very edge). I've never tested this theory but it would be easy to test by placing a piece of tin foil under the rubylith to ensure absolutely no exposure.

This is a good hypothesis. It would tally with my experience of seeing the problem get worse in very humid conditions. Thinking back to last summer the darkroom was like a sauna and was the first and worst time I encountered the fog. It has been more subtle recently. Just looking at Christina Anderson's excellent book, she writes "Fog (non-image colour, usually a grey) can be from heat, light, or chemistry. The increase of heat and humidity can lead to fogging and increased chemical reaction. For instance, having the paper sit too long in a warm humid room before exposure". If edges have greater moisture content and are more reactive as you point out, this could well be the explanation.

I use 'restrainer' in it's broadest sense. The dichromate in the developer is a restrainer. You can also put restrainers in the sensitiser but that is less than ideal IMO.

I'm glad you like the washi tape. Sadly I can't find any in Switzerland so I have to order it from the UK :-(

I remember reading that in your book. My negatives are derived from methods not to be discussed on this forum. More often than not, too much contrast is the problem. That's a shame you can't get the tape, but the norm I guess for us European printers when it comes to acquiring alt process materials in general. Apart from the tape and paper, I'm struggling to remember the essentials I don't import from America.

Thanks again for the help!