Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,548   Posts: 1,573,037   Online: 812
      
Page 1 of 4 1234 LastLast
Results 1 to 10 of 36
  1. #1

    Join Date
    Sep 2009
    Shooter
    Medium Format
    Posts
    42

    paper gelatin / alum sizing, multitude of recipes

    Hi all,

    I'm thinking about gelatin-based sizing again, and have researched different formulas online, and well it seems that there are as much different formulas / ratios / recipes as there are different printers.

    Some people write to mix gelatin and alum hardener together before applying, some instruct to apply successive coatings of gelatin then alum several times, and each person gives different solution proportions. I could try all of them for sure, but that seems quite overkill. As all this is chemistry (albeit a bit complicated one), there should at least be a ideal gelatin/alum ratio optimal for hardening of the gelatin, which can then be more or less diluted in water and applied in different ways ... what do u think ?

  2. #2

    Join Date
    Sep 2005
    Location
    Istanbul, Turkey
    Shooter
    Multi Format
    Posts
    652
    I only use (and recommend) formalin for hardening gelatin sizing... (0.2ml per 1g dry gelatin, I melt the gelatin and stir in the formalin, keep it hot, coat and discard the excess.) Can't you buy it in Belgium?

  3. #3
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,394
    Images
    148
    There's two alums used in hardening gelatin, plain Alum a generic term usually means Potassium Aluminium Sulphate and it's used mainly in hardening fixers but only works in acid solution lower than about pH5.

    The other, Chrome alum, is Potassium Chrome Sulphate which has greater hardening properties and is used in commercial film & paper emulsions as well as for Gelatin subbing layers.

    Both Formaldehyde & Chrome alum work well when sizing with gelatin but the choice may depend on what the papers going to be used for.

    Ian

  4. #4

    Join Date
    Sep 2009
    Shooter
    Medium Format
    Posts
    42
    Ian, I can't get any chrome alum over here (unless I order it in big quantity online) and formalin (formaldehyde) is not openly available to the public I think, unless you're getting it online again. Where are u getting it in Istanbul ?

    anyway, that doesnt change the question of the very different gelatin concentrations and techniques that everyone describes...

  5. #5
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,394
    Images
    148
    My stocks of Chrome alum & Formaldehyde are back in the UK I've had them for years.

    I've used both for subbing with gelatin and also in emulsions (I used to make them commercially). The actual quantity you need to add depends on the gelatin you're using, the degree of hardness required, and what you're trying to achieve that's why quantities are vague and vary a lot.

    Ian

  6. #6

    Join Date
    Sep 2005
    Location
    Istanbul, Turkey
    Shooter
    Multi Format
    Posts
    652
    Dry drugstores / pharmacies if you can't but it from a chemistry dealer (as I do it in Istanbul); maybe they'll give you a little (100ml?)... I understand there's a certain difficulty in obtaining it in Europe or the U.S. because it's a precursor chemical for narcotic drugs or some other controlled substances.

    Edit: You may try to find an embalmer too; probably they stock formaldehyde...

  7. #7
    Hexavalent's Avatar
    Join Date
    Nov 2009
    Location
    Ottawa, Ontario, Canada
    Shooter
    Multi Format
    Posts
    549
    Blog Entries
    3
    Formalin is sometimes available from fish aquarium suppliers. Glutaraldehyde is also sold as a medical sterilant, often used by tattoo artists. You may have to do a little research to find out what the brand names are in your locale.

    As there is great variance in gelatin, there is also a great variance in the quantities/type of hardener required to achieve a specific result.
    There is no real one-size-fits-all hardening formula.
    - Ian

  8. #8

    Join Date
    Apr 2008
    Location
    Santa Cruz, CA
    Shooter
    Multi Format
    Posts
    167
    Images
    17
    Quote Originally Posted by Xandros View Post
    Hi all,

    I'm thinking about gelatin-based sizing again, and have researched different formulas online, and well it seems that there are as much different formulas / ratios / recipes as there are different printers.
    For sure there are a lot different formulas & techniques.

    I am using 21g gelatin ( knox or photo grade ) in 1000ml H2O. I have used it hardened and unhardened. I use about 5ml of glyaxol or 2gr of Chrom Alum as a hardener. I just tried the chrom Alum for the 1st time a month ago and I think I like it a bit better than the glyaxol. I combine the hardener with the gelatine and soak the sheets in a tray for 10min. A very light squeegee and hang to dry. I find letting them cure for at least a few days hardens better. I use this for gum printing and for gum-overs.

  9. #9

    Join Date
    Sep 2009
    Shooter
    Medium Format
    Posts
    42
    Ok thanks all, I tried pharmacies for glyoxal here and its extremely expensive (like 20 € for 10ml), have to ask for formalin & glutaraldehyde yet ... don't have access to chrome alum and potassium alum works but it swells after a few layers so maybe I need to re-size between print layers

  10. #10
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,394
    Images
    148
    Are you still using Avoirdupois weights ? 2gr is 2 grains or do you mean grams ?

    Ian

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