Re: (Fwd) Re: EOS: Light comming into A2E

[eml@xxxxxxxxx]

I have run across this with HIE 135.  I doubt that light-fogging in the tank is at fault.  More likely, based on the fogging that I saw, it is caused by the 
reel pressing physically on the film.  The effect is most likely similar 
to the pressure fogging "half moons" that occur when film buckles while
being put onto a stainless steel reel.  

I have also had similar marks on the edges of 4x5 litho film in a tank
with curved film channels, and with Tri-X 120 in a Kodacraft apron-type
tank.

This is my best guess.
Ed Lukacs

> 
> 
> On Tue, 10 Jun 1997, Greg Pease wrote:
> 
> > the only experience i have with plastic is using a plastic reel to 
> > process my first roll.  the sprocket hole area and part of the image area 
> > of the film was (ever so slightly) fogged from where the plastic reel 
> > touched the film.
> 
> Hmmmm...what is confusing to me, is that usually the film is loaded onto
> the reel and placed in a light tight tank.  If light fogging were causing
> this, why wouldn't the whole roll be affected?  I must be missing
> something here.  The reel shouldn't be generating light inside the tank!
> 
> > however i just got a test roll back from the lab.  this roll 
> > was also processed on a plastic reel and shows no such fogging.  hmmm.
> 
> It is this conflicting data that has been bothering me.  I would think we
> should be able to solve some of these mysteries.  I do have a book on
> plastics in my lab.  I'll try to look and see if there is any IR
> transmission data for various plastics listed.  On a purely practical note
> though, couldn't we create a list of equipment that has already been
> tested by members of this list as being "safe"?  Perhaps a shorter (?)
> list would be one of items known to be "unsafe".
> 
> - Wayde
>   (allen@xxxxxxxxxxxxxxxx) 
> 
> 
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- -- 
    _/_/_/_/ _/_/    _/ _/   | Edward M. Lukacs 
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