anti-halation backing washout

ericdan

Member
Joined
Feb 28, 2014
Messages
1,359
Location
Tokyo
Format
35mm RF
Why does this dye not wash out during the other steps of the process?
Is it somehow resistant to developer, stop bath and fixer?

I am surprised how much of this is washing out when you let the film sit in water for 10 - 15 mins without agitation. I've noticed this for Neopan, Tri-X and HP5+

Steps are:
  1. Dev without pre-wash
  2. stop bath
  3. Fix
  4. Ilford wash (I see only a very slight tint to the water I dump)
  5. Fill with water and let sit without agitation (deep purple/pink water dumps)
 

Andrew O'Neill

Moderator
Moderator
Joined
Jan 16, 2004
Messages
11,767
Location
Coquitlam,BC Canada
Format
Multi Format
Yes, I see it with HP5 a little but way more pronounced with TMY and TMAX sheet films. I developed some TMAX 8x10 this past week and left them soaking in a tray of water. Came back 30 minutes later, and very pink water. Dumped and refilled. Came back another 30 minutes and still quite pink. Even looking at the film base, it appeared quite clear to my eyes... It took several soakings before I got clear water.
 

bence8810

Member
Joined
Oct 18, 2015
Messages
377
Location
Tokyo
Format
Multi Format
I always do like you say above and then let is sit for 30 minutes. Most films clear within this period but the TMAX films need a little more. With TMAX the tank looks full on purple.

Ben
 

RalphLambrecht

Subscriber
Joined
Sep 19, 2003
Messages
14,560
Location
K,Germany
Format
Medium Format
somethe anti halation dye washes out in every process step.the longer your wet times;the less dye is left;not that it does any harm though;it's just aesthetics.
 

darkroommike

Subscriber
Joined
Mar 22, 2007
Messages
1,673
Location
Iowa
Format
Multi Format
Tmax films can take about twice the fixing time of other films and there's one school of thought that says you can not properly fix Tmax films in sodium thiosulfate fixes at all. So double your fixing times or do three times the clearing time or use two fixing baths for 5 minutes each (we did this at the paper I worked for) and then a brief rinse and a long ten minute bath in clearing agent before washing.
 

Photo Engineer

Subscriber
Joined
Apr 19, 2005
Messages
29,018
Location
Rochester, NY
Format
Multi Format
It may be sensitizing dyes left in the film.

In any case, all of these should be destroyed by a sulfite bath.

PE
 

Gerald C Koch

Member
Joined
Jul 12, 2010
Messages
8,131
Location
Southern USA
Format
Multi Format
There are 4 types of anti-halation coatings.

1. An emulsion layer containing a water soluble dye. The most common situation.
2. The anti-halation dye is incorporated in the film base and therefore cannot be washed out.
3. The anti-halation coating consisting of a layer containing colloidal silver. Used with reversal films where it is bleached out as a normal part of the processing.
4. A layer of carbon black (remjet coating) located on the back surface of the base. Used with cine color negative films. It must be removed as a separate step.

I am amused at the amount of handwringing over whether the AH coating is completely washed out. It has NO effect on film processing. Even in a worst case scenario its presence would only lengthen printing times.
 

Xmas

Member
Joined
Sep 4, 2006
Messages
6,398
Location
UK
Format
35mm RF
The wash water needs to be tempered within 2C of developer.
I always use HCA with negatives, and fix by inspection.
 

Photo Engineer

Subscriber
Joined
Apr 19, 2005
Messages
29,018
Location
Rochester, NY
Format
Multi Format
michael_r said:
Jerry - there appears to be a 5th type when it comes to B&W sheet film (Kodak, Ilford) - soluble dye on the base side. This seems to be why you can get uneven removal of the dye if there is insufficient flow of chemistry behind the film.
Click to expand...

This is still a form of AH dye.

PE
 

Old-N-Feeble

Member
Joined
Feb 22, 2012
Messages
6,805
Location
South Texas
Format
Multi Format
I just researched it and there are indeed films with the AH layer between the base and the emulsion. I didn't know any films were made that way. It seems it would be very difficult to remove the AH layer in such a configuration. I'm guessing it's designed to either dissolve or simply lose its density in a certain chemical. Otherwise it seems like a very long wash time is needed.
 

Photo Engineer

Subscriber
Joined
Apr 19, 2005
Messages
29,018
Location
Rochester, NY
Format
Multi Format
Many sheet films have a different backing to allow retouching. This has changed recently.

Also, films contain a carbon powder addendum that adds conductivity to the support reducing static electricity and also to prevent light piping.

PE
 

Gerald C Koch

Member
Joined
Jul 12, 2010
Messages
8,131
Location
Southern USA
Format
Multi Format
As PE points out a particular film layer can serve multiple purposes. In cine film the remjet coating provides lubrication and protection against static electricity. For sheet films the backing layer also provides a "tooth" for retouching pencils and dyes. My original post tried to keep things simple and to the point.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…