Jump to content


Photo

long-term effects of skip bleach process on negative


  • Please log in to reply
5 replies to this topic

#1 Rob Wilton

Rob Wilton
  • Basic Members
  • PipPip
  • 45 posts
  • Cinematographer

Posted 16 May 2007 - 08:39 AM

Dear all,
Ive looked through the archives but cannot find much information on this specific topic.
If its there could anybody post a link for me, I would be very grateful.

What I basically want to know is whether a full or partial skip bleach process on the negative will have any long-term effects?
Someone I know who works for Kodak warned that the negative will become unstable and slowly turn black within months..
Its sounds strange, because I read that Minority Report had bleached bypass on its neg...

Thanks for your help!

cheers,

Rob Wilton
  • 0

#2 Robert Houllahan

Robert Houllahan
  • Sustaining Members
  • 1582 posts
  • Industry Rep
  • Providence R.I.

Posted 16 May 2007 - 09:53 AM

Dear all,
Ive looked through the archives but cannot find much information on this specific topic.
If its there could anybody post a link for me, I would be very grateful.

What I basically want to know is whether a full or partial skip bleach process on the negative will have any long-term effects?
Someone I know who works for Kodak warned that the negative will become unstable and slowly turn black within months..
Its sounds strange, because I read that Minority Report had bleached bypass on its neg...

Thanks for your help!

cheers,

Rob Wilton



This is true a bypass keeps the silver in the film instead of washing it out and the silver will eventually tarnish producing the blackening. This does not happen right away but it is a time sensitive process. You can run a bypass and then rewash the film later (re process it) with the bleach tanks to wash the silver out and mostly reverse the bypass process.

Why is it surprising that minority report had a bypass? that was the look they wanted and the finished film probably got a 3 strip B+W separation master at the end of post for archival storage.

-Rob-
  • 0

#3 Dominic Case

Dominic Case
  • Basic Members
  • PipPipPipPip
  • 1357 posts
  • Other
  • Sydney Australia

Posted 17 May 2007 - 03:12 AM

Hmmm. Not sure about the tarnishing, Rob.

After all, it's the same silver that you have in b/w film, and that lasts long enough! In fact it is a very stable archival medium.

There is no evidence to suggest that a bleach bypassed negative will have any shorter life than one with the full process - so long as it has been fully fixed, washed and dried, and is stored in the proper environemnt with regard to temperature and humidity.

However, labs don't usually have the resources to do extensive Arrhenius testing to determine the long-term prospects of blaachbypassed film (or normal film for that matter) - and I know that the manufacturers (who do this testing on normally processed film) can't really provide any data on film that has not been processed to their specifications.

Now cross-processing (reversal through a neg bath) is a different matter, and that has a seriously short life unless a stabiliser is added to the ECN2 process.
  • 0

#4 Robert Houllahan

Robert Houllahan
  • Sustaining Members
  • 1582 posts
  • Industry Rep
  • Providence R.I.

Posted 17 May 2007 - 12:00 PM

Hmmm. Not sure about the tarnishing, Rob.

After all, it's the same silver that you have in b/w film, and that lasts long enough! In fact it is a very stable archival medium.

There is no evidence to suggest that a bleach bypassed negative will have any shorter life than one with the full process - so long as it has been fully fixed, washed and dried, and is stored in the proper environemnt with regard to temperature and humidity.

However, labs don't usually have the resources to do extensive Arrhenius testing to determine the long-term prospects of blaachbypassed film (or normal film for that matter) - and I know that the manufacturers (who do this testing on normally processed film) can't really provide any data on film that has not been processed to their specifications.

Now cross-processing (reversal through a neg bath) is a different matter, and that has a seriously short life unless a stabiliser is added to the ECN2 process.


Well shivver me timbers!!, I stand corrected ;) I was under the impression that Bypass has a shorter shelf life and I think I got that impression from Brad here at the lab, amongst others, maybe this is a Emulsion urban myth? Could the interaction between the silver and the color couplers/dyes have something to do with this? thus the alleged difference when compared to B+W?? I think we may have a Bypass job in storage in our "vault" maybe even something from the 80's might be interesting to see if that's so and take a look.

X-Process Ektachrome certainly does have a shortness but it's a seriously cool look and we run allot of it in Super8 for transfer. Is there a particular stabilizing agent that is reccomended Dominic?

-Rob-
  • 0

#5 Brian Pritchard

Brian Pritchard
  • Basic Members
  • PipPipPipPip
  • 328 posts
  • Other
  • Stoke-on-Trent, UK

Posted 18 May 2007 - 03:14 AM

Hmmm. Not sure about the tarnishing, Rob.

After all, it's the same silver that you have in b/w film, and that lasts long enough! In fact it is a very stable archival medium.

There is no evidence to suggest that a bleach bypassed negative will have any shorter life than one with the full process - so long as it has been fully fixed, washed and dried, and is stored in the proper environemnt with regard to temperature and humidity.

However, labs don't usually have the resources to do extensive Arrhenius testing to determine the long-term prospects of blaachbypassed film (or normal film for that matter) - and I know that the manufacturers (who do this testing on normally processed film) can't really provide any data on film that has not been processed to their specifications.

Now cross-processing (reversal through a neg bath) is a different matter, and that has a seriously short life unless a stabiliser is added to the ECN2 process.

I agree with everything that Dominic says; also remember that for the last 60 years or so we have effectively used bleach bypass for sound tracks on colour film. The sound track area was re-developed to bring back the silver after bleaching. I have never come across any tarnishing of sound tracks.

Brian
  • 0

#6 Robert Houllahan

Robert Houllahan
  • Sustaining Members
  • 1582 posts
  • Industry Rep
  • Providence R.I.

Posted 18 May 2007 - 11:25 AM

I agree with everything that Dominic says; also remember that for the last 60 years or so we have effectively used bleach bypass for sound tracks on colour film. The sound track area was re-developed to bring back the silver after bleaching. I have never come across any tarnishing of sound tracks.

Brian



Well I guess this myth is busted :rolleyes: But it is something very many people seem to believe, I did and I work at a lab, but then again there is always more to learn...

-Rob-
  • 0


Metropolis Post

Abel Cine

Willys Widgets

Visual Products

Ritter Battery

Technodolly

Gamma Ray Digital Inc

The Slider

Broadcast Solutions Inc

Aerial Filmworks

Wooden Camera

CineTape

rebotnix Technologies

Opal

Paralinx LLC

Tai Audio

Glidecam

Media Blackout - Custom Cables and AKS

FJS International, LLC

CineLab

Rig Wheels Passport

Abel Cine

Broadcast Solutions Inc

Metropolis Post

CineLab

Willys Widgets

Tai Audio

Wooden Camera

Gamma Ray Digital Inc

Technodolly

FJS International, LLC

Rig Wheels Passport

rebotnix Technologies

Ritter Battery

Opal

Aerial Filmworks

Media Blackout - Custom Cables and AKS

Visual Products

CineTape

Paralinx LLC

The Slider

Glidecam