anti-halation backing washout

[ericdan]

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]

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.

 

[ericdan]

Same here, I repeated step 5. about three times before I got semi-clear water.

 

[bence8810]

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]

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)

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.

 

[TheFlyingCamera]

I always pre-wet my film, and most of the dye comes off in the pre-wet, from my experience. The pink you see with TMAX could also be from insufficient fixing. The TMAX films need extended fixing.

 

[darkroommike]

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]

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]

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]

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)

The wash water needs to be tempered within 2C of developer.
I always use HCA with negatives, and fix by inspection.

 

[Photo Engineer]

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.

This is still a form of AH dye.

PE

 

[Old-N-Feeble]

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]

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]

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.