Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,990   Posts: 1,524,207   Online: 1174
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 29
  1. #11
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,221
    Images
    148
    You can't use a colour bleach as that will also remove the remaining un-processed silver halide as that you need to re-expose chemically or with light & develop to form the positive.

    Ian

  2. #12
    Steve Smith's Avatar
    Join Date
    May 2006
    Location
    Ryde, Isle of Wight
    Shooter
    Medium Format
    Posts
    8,555
    Images
    122
    Our local photographic shop has a Tetenal kit for doing this. It's amongst a bunch of sale items and is going quite cheap. Does anyone have any experience of these kits?


    Steve.
    Attached Thumbnails Attached Thumbnails !BOoq+eg!Wk~$(KGrHgoOKiQEjlLmEZt(BJvqQQzqUg~~_1.JPG  

  3. #13
    Athiril's Avatar
    Join Date
    Feb 2009
    Location
    Melbourne, Vic, Australia
    Shooter
    Medium Format
    Posts
    2,495
    Images
    28
    Quote Originally Posted by Ian Grant View Post
    You can't use a colour bleach as that will also remove the remaining un-processed silver halide as that you need to re-expose chemically or with light & develop to form the positive.

    Ian
    You're thinking about a combined bleach and fix or when there is a bleach after last developing (followed by a subsequent fix)

    The bleach doesn't remove silver halide, it converts metallic silver into bromide, (ie: the developed silver from the first bath), then second developer, develops the exposed silver (which is everything, bar what was developed in the first hence reversal).

    The fix wont remove the second developed silver, but it will remove the first converted by the bleach silver.

  4. #14
    gainer's Avatar
    Join Date
    Sep 2002
    Posts
    3,726
    Images
    2
    Farmer's Reducer does remove the negative image. A ferricyanide bleach followed by a sulfite clearing bath also removes the negative image. The first development should be to high contrast. After the bleaching and clearing, the second development must be to completion, and Dektol or similar may be used.

    That is the process in general, but I am not an expert at using it. There are some among us who are expert, aren't there, Jordan?
    Gadget Gainer

  5. #15

    Join Date
    Jun 2003
    Location
    Los Angeles, CA 90061
    Shooter
    35mm
    Posts
    170
    We make reversal chemicals for this process including chromate bleach.

  6. #16
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,221
    Images
    148
    A an image bleached in Fericyanide on it's own can be redeveloped even when no halide is added which is why it's not used in B&W reversal processes.

    Quote Originally Posted by Athiril View Post
    The bleach doesn't remove silver halide, it converts metallic silver into bromide, (ie: the developed silver from the first bath), then second developer, develops the exposed silver (which is everything, bar what was developed in the first hence reversal).
    That's exactly what you don't want, the bleach needs to convert the silver into soluble silver salt that washes out of the image, If you convert the silver back to a bromide or chloride it will get re-exposed and re-develop with the positive.

    Ian

  7. #17
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,221
    Images
    148
    Quote Originally Posted by Steve Smith View Post
    Our local photographic shop has a Tetenal kit for doing this. It's amongst a bunch of sale items and is going quite cheap. Does anyone have any experience of these kits?

    Steve.
    Tetenal chemistry is extremely good, it should be worth buying.

    Ian

  8. #18

    Join Date
    Sep 2004
    Location
    Toronto, Canada
    Shooter
    Multi Format
    Posts
    587
    Quote Originally Posted by EASmithV View Post
    How do I take negative BW film and develop it as a positive BW slide?
    The technique is called "reversal processing" and there are dozens of threads about it here and around the Net. A search will turn up lots of useful information here.

    Quote Originally Posted by Ian Grant
    That's exactly what you don't want, the bleach needs to convert the silver into soluble silver salt that washes out of the image, If you convert the silver back to a bromide or chloride it will get re-exposed and re-develop with the positive.
    Agreed with Ian here -- for a bleach to be usable in B&W reversal, it must be able to completely solubilize the metallic Ag negative image without affecting the AgX positive image. This is not possible with iron(III) based bleaches, AFAIK. In practice the only commonly used bleaches for B&W reversal are dichromate- or permanganate-based.

  9. #19
    EASmithV's Avatar
    Join Date
    Aug 2008
    Location
    Maryland
    Shooter
    Multi Format
    Posts
    1,873
    Blog Entries
    4
    Images
    121
    Ok, a slightly different thing now-

    Can you please look over this and tell me where I go wrong?

    I'm going to reverse process Plus-X negative film in 16mm

    First dev: HC-110 for 5 minutes
    Stop bath for 3 minutes
    Bleach in normal room light until it looks good (Farmer's reducer?)
    Hold about 10 cm under a 60 watt incandescent light and re-expose on each side for about 30 seconds
    Re-develop in normal room light with HC-110 until it looks proper
    (I eventually want to try using Caffenol for the second developer)
    Fix 5 min
    Last edited by EASmithV; 04-21-2009 at 04:05 PM. Click to view previous post history.
    www.EASmithV.com

    "The camera is an instrument that teaches people how to see without a camera."— Dorothea Lange
    http://www.flickr.com/easmithv/
    RIP Kodachrome

  10. #20
    EASmithV's Avatar
    Join Date
    Aug 2008
    Location
    Maryland
    Shooter
    Multi Format
    Posts
    1,873
    Blog Entries
    4
    Images
    121
    With plenty of rinses of course
    www.EASmithV.com

    "The camera is an instrument that teaches people how to see without a camera."— Dorothea Lange
    http://www.flickr.com/easmithv/
    RIP Kodachrome

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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