salted paper fogging woes

Discussion in 'Alternative Processes' started by gwatson, Oct 24, 2006.

  1. gwatson

    gwatson Member

    Messages:
    146
    Joined:
    Feb 2, 2005
    Location:
    Windsor, UK
    Shooter:
    Multi Format
    Hi all

    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.

    Many thanks

    Geoff
     
  2. Justin Cormack

    Justin Cormack Member

    Messages:
    181
    Joined:
    Jul 17, 2006
    Location:
    London
    Shooter:
    Large Format
    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.
     
  3. gwatson

    gwatson Member

    Messages:
    146
    Joined:
    Feb 2, 2005
    Location:
    Windsor, UK
    Shooter:
    Multi Format
    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) ;-).

    Thanks again

    Geoff
     
  4. Justin Cormack

    Justin Cormack Member

    Messages:
    181
    Joined:
    Jul 17, 2006
    Location:
    London
    Shooter:
    Large Format
    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.
     
  5. Jim Noel

    Jim Noel Member

    Messages:
    2,144
    Joined:
    Mar 6, 2005
    Shooter:
    Large Format
  6. gwatson

    gwatson Member

    Messages:
    146
    Joined:
    Feb 2, 2005
    Location:
    Windsor, UK
    Shooter:
    Multi Format
    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.

    Geoff
     
  7. Jerevan

    Jerevan Subscriber

    Messages:
    2,033
    Joined:
    Nov 19, 2004
    Location:
    Sweden/Germany
    Shooter:
    35mm
    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.
     
  8. Justin Cormack

    Justin Cormack Member

    Messages:
    181
    Joined:
    Jul 17, 2006
    Location:
    London
    Shooter:
    Large Format
    I think the gelatine is just for sizing, not necessary. I might try some though with some of my paper.
     
  9. gwatson

    gwatson Member

    Messages:
    146
    Joined:
    Feb 2, 2005
    Location:
    Windsor, UK
    Shooter:
    Multi Format
    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.)

    Cheers

    Geoff
     
  10. Lukas Werth

    Lukas Werth Member

    Messages:
    266
    Joined:
    Oct 26, 2005
    Location:
    Pakistan
    Shooter:
    Multi Format
    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?
     
  11. Jerevan

    Jerevan Subscriber

    Messages:
    2,033
    Joined:
    Nov 19, 2004
    Location:
    Sweden/Germany
    Shooter:
    35mm
    What salt do you use? If it's standard table salt, go check the ingredients. Salt isn't always sodium chloride alone. Some kind of anti-caking is often used, and this may be detrimental to printing.
     
  12. gwatson

    gwatson Member

    Messages:
    146
    Joined:
    Feb 2, 2005
    Location:
    Windsor, UK
    Shooter:
    Multi Format
    Hi. This is the process I use:

    1: mix high grade sod chloride, sod citrate and gelatine. Immerse for 30 sec with constant agitation. Air dry.

    2: Coat 12% silver nitrate in safe light. Air dry. :- paper fogs.

    I think the problem lies in either the salt mix is not using distilled water and the silver is reacting with a salt/mineral in the water, the lack of citric acid, or the papers I use are buffered with chalk which reacts with the silver.

    Personally, I think the problem is with the recipe. I need citric acid with the silver and I will use distilled water for the salt solution. It will be a week or so until I can try this again and will update the thread accordingly. The recipe I am using is in the Beyond Monochrome book, BTW.

    Thank you all for your replies.

    Geoff
     
  13. Jerevan

    Jerevan Subscriber

    Messages:
    2,033
    Joined:
    Nov 19, 2004
    Location:
    Sweden/Germany
    Shooter:
    35mm
    The chalk (or possibly some other detrimental component) in the paper could be the culprit. Another possible idea is if you use a brush with a metal ferrule, which could react with the solution.

    Try Ruscombes Buxton (or the gelatin-sized Talbot) papers, if nothing helps. They should be available from:

    John Purcell
    15 Rumsey Road, London, SW9 OTR
    Tel: +44 (0)20 - 7737 5199
    Fax: +44 (0)20 - 7737 6765

    according to the www.alternativephotography.com site. Otherwise it can be ordered directly from Ruscombe Mills.

    Let us know how it works out in the end.
     
  14. Lukas Werth

    Lukas Werth Member

    Messages:
    266
    Joined:
    Oct 26, 2005
    Location:
    Pakistan
    Shooter:
    Multi Format
    I have just noted that you write "imerse": don't do that, float! Immersing used to create problems for me, though I don't remember whether fogging was among them.

    I don't remember whether distilled water is necessary for the salting solution. It should not lead to fogging, though: when the silver nitrate comes into contact with tab water it forms silver chloride (I think I remember) which you see as the ater turning milky in the wash after exposure.

    But citric in the silver solution is certainly advisable.