Salt Print Bleaching problem

[Uncle Goose]

So after making my own silver nitrate I tried to do some Salt Printing (2% Sodium Chloride, 12% Silver Nitrate). The good thing is that i got an image, the bad thing is that the moment I put it in the fix (10% Sodium Thiosulphate and about 2 grams Sodium Bicarbonate) the whole picture bleaches to a diarrhea like brown color. Don't really know what the problem is, might it be that I have to grossly overexpose the salt print under my UV tubes in order to compensate for the bleach? Or did I miss something else?

 

[garysamson]

Yes, you need to over expose by 1.5 to 2 stops to have the proper density when the print dries. I am assuming you are rinsing the print in water until the water runs completely clear and that you are not gold toning the print before it goes into the fixer.

 

[Uncle Goose]

Yep, I rinse enough and do not gold tone. I will try this evening again with longer exposures.

 

[Loris Medici]

There's considerable dry down with salt (and iron-silver) prints... Does the print STILL stay the same way (weak / anemic) AFTER waiting at least 6-8 hours (to let it dry thoroughly)? Definitely try gold-thiourea toning BTW...

Regards,
Loris.

 

[Herzeleid]

My prints go brown in the fixer too, but I never observed bleaching, just color changed. The tones get slightly darker, have reddish maroon like color after complete dry down.
I use a hair dryer to hasten it for test strips.
Exposure can be misleading, when I started experimenting salt print I thought 3-4 minutes exposure was ok, then I thought 7 is good, but later I found out 12 min was spot on.
If you are using film, the exposures might be even longer.
Well the times can differ for everyone's workflow but reaching the darkest tone in the print during exposure, not necessarily means it is exposed enough for salt printing IMHO.

 

[Uncle Goose]

At the moment I did some shots in the dark concering time and I found out that not all papers work that well, the aquarelle works great but the more glossy paper doesn't work that well. I coated some aquarelle and will expose them tonight. I will make a long exposure first and then go from there. Thanx for the already interesting info provided here.

 

[Herzeleid]

One thing that came to my mind, you haven't mention sodium citrate in the formula, it is not essential but it decreases contrast and affects the color as well as the gelatin ratio. When I tried to increase contrast of the print without adding potassium bichromate, and keeping the negative density a constant.
I completely eliminated sodium citrate and increased gelatin ratio to %3 the resulting prints color were according to a painter friend of my mine was diarrhea brown even when dry. The worst I have ever seen. I like the salt print colors without gelatin very much but I use gelatin anyway. BTW I am fairly new to the process myself.

You should take a look at Young's applied science thesis on the color of Salt Prints, I find it a bit more comprehensive than the Salt Printing Manual.
http://researchbank.rmit.edu.au/eserv/rmit:7850/Young.pdf

Bleach is as stated by the others is probably related to exposure, but the final color might be a combination paper, gelatin ratio and salt formula.

 

[Uncle Goose]

I didn't use Sodium Citrate, I know that it has a bleaching effect. I tried to do longer exposures and have now a nicer Sepia color. I'm now in progress to expose even longer to see where the limit is. I don't use Gelatine at the moment, might try that too. And that PDF went straight to my E-reader, always good to read when between classes.

 

[Loris Medici]

Do you have a 21 or 31 step tablet? (Stouffer or PDN transparencies...) It's a very useful tool for the purpose of determining the correct exposure!

Regards,
Loris.

 

[Uncle Goose]

Do you have a 21 or 31 step tablet? (Stouffer or PDN transparencies...) It's a very useful tool for the purpose of determining the correct exposure!

Regards,
Loris.

Nope, nothing like that but I don't feel that I really need it at this point, I wouldn't know where to get those transparencies here in Belgium, it's a wasteland here in terms of photographic specialties.

I did longer exposures (see attachment), this is a 30min exposure with my UV light source, it however doesn't have much difference with the 20min exposure I did so maybe 25min will be the benchmark for me. I'm very pleased with the result, it looks a little better IRL than scanned.

Had some contamination from my brush but that will be eliminated with better cleaning procedure.

 

[Herzeleid]

Well, it certainly looks ok, I am glad you nailed it. 30 mins may be a bit overexposed as you said, considering that there is no paper base white , but I believe that is personal matter of choice.

Loris is very right, some sort step wedge is very very useful to determine correct exposures, it would save you from a lot of trouble.

BTW I want to share my experience with brushes, I feel that the brush will always cause contamination, black dots, irregular densities, distracting patterns and so on, no matter how careful you are.
A glass rod/puddle pusher is perfect for Salt print. If you decide to include gelatin in future, a glass rod would save you from lots of troubles.

Regards

 

[Uncle Goose]

I use foam brushes at the moment, I bought some new ones and will dedicate them only to salt print, that might solve the contamination problem for the largest part. We'll see in the future. Thanx for all the useful info everybody put in here.

 

[Gadfly_71]

A few things you may want to look into:

- Buffered papers can cause problems, odd color shifts, etc. Finding a good unbuffered paper will aid considerably (the lighter the better too)

- Have a negative with the correct tonal scale. Good negatives for salt should be nearly unprintable in silver even with the softest contrast grade.

- Avoid tap water in the first wash. Chlorinated water can have undesirable effects on your prints. After the print is toned and fixed, final wash in tap water is fine.

- Straight Hypo works fine without any additives. I normally use 1 heaping tablespoon of crystals to 1 liter (or 1 quart) of distilled water

- Toning (especially with a gold chloride solution) will help, not only with permanence but also with final color

- Rod coating is fine, but a good Hake, sable, or camel brush works well too. I've never had good luck with foam brushes.

YMMV

 

[cliveh]

Straight Hypo works fine without any additives.

William Henry Fox Talbot would not agree, but perhaps I refer to photogenic drawings rather than present day salt prints.