salted paper fogging woes
Having issues with pre-exposure fog on salted paper. I have tried Waterford, BFK Rives, and Fabriano 5, all fog to some extent whilst drying. The fog can't be light induced, so has anyone any suggestions?
Method: Salt prints in Sod Chloride, Sod Citrate, and Gelatin. Allow to dry. Coat paper in 12% Silver Nitrate. Paper starts to fog within 40 mins or so.
I didn't use distilled water in the silver solution. Could this be the cause? Is the silver reacting to something in the paper - sizing, buffer etc.?
Any help gratefully received.
My "recipe" has the sodium citrate mixed with the silver nitrate not with the salt - the paper is just salted. This may help. Havent used gelatin either (photo grade or food grade?) yet. Had no fogging problems so far. Also used deionised water (cheap for refilling batteries etc) - this is a likely cause too.
If you have tried several papers it is less likely to be them I think.
Not an expert yet though.
Thanks Justin. I converted our kitchen steamer to produce enough distilled water and made up a new batch of nitrate solution. Still fogging, although perhaps a little less. I'd be very interested in your recipe for the nitrate solution (if you're telling) ;-).
I have no secrets. My recipe is from Spirits of Salts, a very helpful book.
It suggests that chemical contamination of the nitrate wil cause coloured spots not fogging.
The recipe is 50ml distilled water + 12 grams silver nitrate mixed with 50ml of water + 6 grams citric acid (dissolve both solutions then mix).
Not sodium citrate at all - I misremembered.
Salt is a 2% solution - soak the paper for 5 minutes.
Only other note is to avoid fluorescent lights - I coated mine in very dim light, dried with a hair dryer and then left in the dark to completely dry.
Doing some more tomorrow if there is any sun...
I recommend the book, very helpful with what may go wrong, and nice illustrations of what may go right.
sillverprint has a very good and simple explanation of salt printing on their web site. http://www.silverprint.co.uk/
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Thanks all. I think the citric acid is the missing link. I'm also not sure if I need the gelatin if it is only for sizing, although the recipes I've seen that use say that I need organic matter for the process to work. Oh well, suck it and see, I guess. thanks again.
Uhm... the organic matter is actually the citric acid. The gelatin is only for the image itself so that it doesn't sink too far into the paper. If the silver solution sinks too far in, the paper fibers will "come between" you and the image. The gelatin will also give you a slightly warmer tone.
If you are using a paper already sized with gelatin (such as the Talbot paper from Ruscombe) you can leave it out. I think many of the early salt prints were straight onto already sized paper, and it was later on it was discovered what the sizing did to the image.
The sizing doesn't need to be gelatin, either. O'Reilly mentions several different kinds of sizing, for example tapioca starch.
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I think the gelatine is just for sizing, not necessary. I might try some though with some of my paper.
I'm no expert but this is how I understand it. The gelatin does size the paper but in recipes that do not contain any other organic matter, the gelatin is the organic matter. This is why you should not over-heat it when dissolving it. However, I have seen a post somewhere from someone who added citric acid to a gelatin recipe to reduce fog.
However, since the papers I use are all sized in some way, additional sizing may not be required and therefore the gelatin can be replaced by citric acid. Something I'll have to try. If additional sizing is required, I'll try both gelatin and citric acid. (I quite like the gelatin sizing, BTW.)
I am really not sure about your fogging problem, so this is another shot in the dark.
However, I would not skip the gelatine. It improves the picture.
One thing might be worth atry: salt with sod chl and gelatine, and mix the silver nitrate with citric acid - not too much at a time, because in my experience, this solution does not last indefinitely, but goes bad after a few weeks or months.
How is your salting procedure? Do you float the paper on the solution?