Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,940   Posts: 1,585,693   Online: 1014
      
Page 1 of 4 1234 LastLast
Results 1 to 10 of 35
  1. #1

    Join Date
    Sep 2008
    Shooter
    Medium Format
    Posts
    25

    Adhesion to glass plates.

    I noticed that some people regularly have trouble with allowing gelatin to stay on the glass during processing.
    Here is a trick that will really make gelatin stick to the glass strongly even when using the most alkaline developers. Even unhardened gelatin will stay on the glass easily.

    1] Make a stock solution of:
    -- 4ml 3-amino-propyltriethoxysilane (CAS#: 919-30-2)
    -- 5.5ml of Isopropyl Alcohol
    -- 0.5ml De-Ionized Water
    -- Allow this solution to sit for 24 hours
    2] Clean your glass plates well, first with dishwashing liquid and then with a Ammonia based glass cleaner (called Glassex here in Holland)
    3] Take 1ml of the solution made in step 1 and add 20ml of Isopropyl Alcohol to that.
    4] With a clean paper towel rub this solution onto your freshly cleaned glass plates. You will see a white haze appear on the surface of the glass.
    5] Let the plates sit for a few hours to allow the silane to bond to the glass.
    6] Remove the haze from the glass with an ammonia based glass cleaner. (This becomes difficult if you wait more than about four hours)
    7] Your plates can now be stored until the time you are ready to coat them.

    When using this procedure you will not need to pre-sub the plates with chrome hardened gelatin before coating.

    (Please mix your Silane in a well ventilated area because it is not a very pleasant liquid. Wear eye protection and gloves. When using it, I wear a painters mask with a carbon filter.)

  2. #2

    Join Date
    Sep 2008
    Shooter
    Medium Format
    Posts
    25
    Oh, one thing I forgot to mention: The stock solution made in step [1] is good for about a week and should be discarded after that. The diluted solution made in step [4] is good for one day. So, it is a good idea to prepare a good stack of glass when you do this procedure.

    Happy photographing.

  3. #3

    Join Date
    Jun 2004
    Location
    Portland, OR
    Shooter
    4x5 Format
    Posts
    3,268
    Hans - can you recommend a source for the Silane? That's probably not going to be an easy one for most people to get ahold of.

    Also, it's pretty corrosive stuff. I'm glad you mentioned the safety precautions.

  4. #4
    JOSarff's Avatar
    Join Date
    Mar 2008
    Location
    Santa Fe, NM
    Shooter
    8x10 Format
    Posts
    203
    Kirk:

    Bostick & Sullivan carries silane.

    Joe
    There is no such thing as taking too much time, because your soul is in that picture. -Ruth Bernhard

  5. #5

    Join Date
    Jun 2004
    Location
    Portland, OR
    Shooter
    4x5 Format
    Posts
    3,268
    Joe - Thanks. I guess I should check out the other supplies they carry too.

  6. #6

    Join Date
    Jun 2004
    Location
    Portland, OR
    Shooter
    4x5 Format
    Posts
    3,268
    Joe - do you know what strength B&S recommend using it at?

  7. #7
    Nicholas Lindan's Avatar
    Join Date
    Sep 2006
    Location
    Cleveland, Ohio USA
    Shooter
    Multi Format
    Posts
    2,381
    Images
    4
    Quote Originally Posted by Hans2008 View Post
    3-amino-propyltriethoxysilane
    This may be the magic ingredient in the American product "Rain-X Anti-Fog" or "Fog-X", a treatment that makes glass hydrophillic. There is also the complimentary product "Rain-X" (without "anti-fog" in the name) that makes glass hydrophobic.

    Fog-X works very well on camera eyepieces.

    http://www.rainx.com/Products/Windsh.../Original.aspx
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  8. #8
    Struan Gray's Avatar
    Join Date
    Nov 2004
    Location
    Lund, Sweden
    Shooter
    Multi Format
    Posts
    914
    The amino-terminated version is hydrophilic. Hydrophobic coatings can be made using flourinated alkane chains, although the ones I am familiar with are longer than this one (12 or 13 carbon atoms instead of 3).

    The bonding reaction evolves HCl, which can be a problem in some environments. Probably not a biggie in this application, but make sure your containers and any fume-extraction system can handle acids.

    "Self-assembled monolayers" is the buzz-phase of the day if anyone wants to look the details up.

  9. #9
    Struan Gray's Avatar
    Join Date
    Nov 2004
    Location
    Lund, Sweden
    Shooter
    Multi Format
    Posts
    914
    PS: I know that here in the lab we maintain higher safety and quality standards than a hobbiest working with dilute solutions, but silane treatment seems a bit too much of a hassle just to prepare a glass surface for gelatin deposition. For really good silane layers you need to carefully control both water and oxygen in the local environment, and the method proposed here does neither.

    Indium-tin-oxide is nicely hydrophilic, and widely available as a coating on float glass for window panes and patio doors. I would investigate that as an alternate substrate before getting my hands dirty with silane.

  10. #10

    Join Date
    Sep 2008
    Shooter
    Medium Format
    Posts
    25
    For holography we use the silane all the time. It works great. Another holography trick to make a really good coating is to treat one piece of glass with silane. Then treat another piece of glass with Rain-X to make it really hydrophobic. Put on each edge of the Rain-X treated glass a strip of Scotch tape. Warm both plates with a hair drier and put a puddle of emulsion on one of them (emulsion with about 12% of gelatin). Put the other piece of glass on top of it and put this sandwich in the fridge for about two hours and then carefully separate them. The gelatin will stay on the silane treated plate and be perfectly flat. It will need about one hour to dry and is ready for use.

Page 1 of 4 1234 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin