[rollei_list] Re: was Rollei Retro Film now is Rodinal pin holes

----- Original Message ----- 
From: "Dennis Purdy" <dlp4777@xxxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Monday, February 25, 2008 6:50 AM
Subject: [rollei_list] Re: was Rollei Retro Film now is 
Rodinal pin holes


> Richard, or anyone,  do you know what exactly is the cause 
> of pin holes
> in film?  I have tried to research it and find a lot of 
> recommendations
> to avoid stop bath and then I read opinions that stop bath 
> don't really
> do it.  I have just processed some ACROS in Rodinal 1:50 
> and it is
> beautiful but has lots of tiny pin holes.  I use this film 
> a lot and
> have never encountered pin holes before, processing in 
> XTOL or Beutlers
> or R09.  Are pin holes somehow created in development?
> thanks if you know and even if you don't
> Dennis
>
>
    Real pin holes are very rare. They are actual physical 
disruptions in the emulsion caused by gas formation. First 
of all mot films are hardened to the point where such 
disruptions would require very extreme conditions to form, 
if at all. Secondly, few film developers contain carbonates 
these days and its the effervescense of carbonate that 
caused the problem in the old days. Rodinal contains 
hydroxide which I don't think causes outgassing.
    It is possible for apparent pin holes, that is clear 
spots, to form because of dirt on the film during 
development or because of small bubbles of air stuck to the 
surface. The last do not usually show up as pin holes but as 
"air bells" small clear areas with a dark surrounding. 
Jarring the film tank on the bench a couple of times after 
filling it usually knocks off any bubbles but they can 
survive normal agitation if not knocked off.
    Pin holes can be the result of a coating problem. This 
happened to T-max films a couple of times and Ilford has had 
the problem but I have not heard of anything recently and 
its pretty rare.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 

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