Removing emulsion from glass plate

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by John Jarosz, Oct 13, 2006.

  1. John Jarosz

    John Jarosz Member

    Messages:
    149
    Joined:
    May 17, 2006
    Location:
    Chicago area
    Shooter:
    Large Format
    Hi all,

    I have a couple of old glass plates with an unprocessed emulsion on them. I 'd like to use the plates for another project. What's the best way to rmove the original emulsion? If I simply fix the plate is everything rmoved?

    Thanks

    john
     
  2. Jerevan

    Jerevan Subscriber

    Messages:
    1,968
    Joined:
    Nov 19, 2004
    Location:
    Sweden/Germa
    Shooter:
    35mm
    I only have experience with exposed plates, but I think water (or some other liquid) would remove it off from the plate. I'd prefer just to cut a few new glass sheets in the same size (or have someone to do it).

    If they have been kept in the dark and are not exposed, they may be of interest to someone here on APUG. There are a few people around who indulge in exposing old glass plates. :smile:

    EDIT: btw, if you decide to cut plates yourself, be aware that the edges are very sharp. Use something to sand them down a bit so you can handle them safely. Glass cuts can be horrible.
     
    Last edited by a moderator: Oct 13, 2006
  3. raucousimages

    raucousimages Member

    Messages:
    825
    Joined:
    May 12, 2003
    Location:
    Salt Lake
    Shooter:
    Large Format
    Sodium Carbonate in hot water is used to reticulate negs. if you leave it too long the emulsion will just fall off of the film base. Shuld work for plates as well.
     
  4. Roger Hicks

    Roger Hicks Member

    Messages:
    4,913
    Joined:
    May 17, 2006
    Location:
    Northern Aqu
    Shooter:
    35mm RF
    Boiling with caustic soda is traditional. DO NOT use light alloy saucepans! For that matter, ask yourself how much you want to use boiling caustic soda solution...

    Cheers,

    R. (www.rogerandfrances.com)
     
  5. Dave Parker

    Dave Parker Inactive

    Messages:
    4,049
    Joined:
    Aug 14, 2004
    Shooter:
    Multi Format
    I can second, third and fourth this statement!!!! be very careful when handling glass plates that don't have finished edges, I have the scars to prove it!

    :surprised:

    Dave
     
  6. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    25,095
    Joined:
    Apr 19, 2005
    Location:
    Rochester, N
    Shooter:
    Multi Format
    Hot caustic soda will etch glass.

    The best is a sulfuric acid / dichromate solution in which you soak the film. Then you wash in hot water and soak in warm detergent solution. Follow this by another wash and then rinse in distilled water and dry.

    Use rubber gloves to prevent finger prints.

    PE
     
  7. Roger Hicks

    Roger Hicks Member

    Messages:
    4,913
    Joined:
    May 17, 2006
    Location:
    Northern Aqu
    Shooter:
    35mm RF
    That's interesting. I have to admit that this was taken from old books; I had not tried it. I wonder if they just didn't worry about the etching, as they were contact printing anyway.

    Perhaps, too, you could throw more light on something else I have read in old books but never verified. It is that you sometimes get a residual ghost image on (or perhaps more accurately in) the glass even when the gelatine is fully removed. Hard to believe, but I have seen it asserted in more than one old source (sorry, can't remember where).

    Cheers,

    Roger
     
  8. John Jarosz

    John Jarosz Member

    Messages:
    149
    Joined:
    May 17, 2006
    Location:
    Chicago area
    Shooter:
    Large Format
     
  9. donbga

    donbga Member

    Messages:
    2,084
    Joined:
    Nov 7, 2003
    Shooter:
    Large Format Pan
     
  10. John Jarosz

    John Jarosz Member

    Messages:
    149
    Joined:
    May 17, 2006
    Location:
    Chicago area
    Shooter:
    Large Format
    It's a long story.

    I broke the groundglass element of my Hasselblad "Groundglasss focusing adapter". Don't ask how. The fresnel is fine. I cannot find a source of glass .065" thick. The groundglass is NLA from Hasselblad.

    The 2 4x5 glass plates I have are .058 (approx) thick. So the expediant solution seems to be to use the glass to have it ground and sized to fit. I can make some shims to make up the thickness difference.

    Thanks for the ideas.

    John
     
  11. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    25,095
    Joined:
    Apr 19, 2005
    Location:
    Rochester, N
    Shooter:
    Multi Format
     
  12. John Jarosz

    John Jarosz Member

    Messages:
    149
    Joined:
    May 17, 2006
    Location:
    Chicago area
    Shooter:
    Large Format
     
  13. Jerevan

    Jerevan Subscriber

    Messages:
    1,968
    Joined:
    Nov 19, 2004
    Location:
    Sweden/Germa
    Shooter:
    35mm
    I am raised with using millimeters, so I had to convert 0.065" so get an idea of how thick that was (1.651 mm). So, armed with my micrometer I went out to the bench and had a look. The leftover groundglass is 2.35 mm, but the glass I had from some abandoned picture frame is 1.85 mm (0.072 inch), so I don't think you should give up just yet on finding some glass.

    BTW, I am not really into Hasselblad stuff, but am I right in that is two parts - one plastic fresnel and one ground glass part? For what model? Maybe I can source it over here.
     
  14. John Jarosz

    John Jarosz Member

    Messages:
    149
    Joined:
    May 17, 2006
    Location:
    Chicago area
    Shooter:
    Large Format
    You are correct, there are two parts: a typical groundglass and a fresnel.

    It is called "Focusing Screen Adapter" Cat # 41025. Designed for the SWC, but it will fit on the rear of any Hasselblad.

    Regards,

    john
     
  15. Jerevan

    Jerevan Subscriber

    Messages:
    1,968
    Joined:
    Nov 19, 2004
    Location:
    Sweden/Germa
    Shooter:
    35mm
    There is one at B&H for $69, with that part number.
     
  16. John Jarosz

    John Jarosz Member

    Messages:
    149
    Joined:
    May 17, 2006
    Location:
    Chicago area
    Shooter:
    Large Format
    Actually not a bad price. That may be the cheapest solution. Thanks

    john
     
  17. Dave Parker

    Dave Parker Inactive

    Messages:
    4,049
    Joined:
    Aug 14, 2004
    Shooter:
    Multi Format
    The thinnest glass I can get that is acceptable for grinding is 1.94mm thick, most picture frame glass actually is not flat and has waves in it, using picture frame glass, unless the high dollar museum glass is not normally acceptable in this type of application, believe me, if it is glass, we have looked at it and tried to see how it would turn out...that is why I have the glass made for my application, but if I were to do a run of glass for one project like this, the cost factor would be hugh and not economically feasable, it sounds like the B&H route might be your best bet.

    Dave