Re: [Leica] Re: Jobo and wash aids

["Glen M. Robinson" <gmrobinson@imation.com>]

Thomas Kachadurian <kach@freeway.net> on 05/21/99 10:29:11 PM

Please respond to leica-users@mejac.palo-alto.ca.us

To:   leica-users@mejac.palo-alto.ca.us
cc:    (bcc: Glen M. Robinson/DSP/Imation)
Subject:  Re: [Leica] Re: Jobo and wash aids





I may be mistaken but as I understand it it's wash agents (like
permawash) and stabilizers (like Jobo's own) that are a problem, not
wetting agents.


>>The current issue of the JOBO newsletter arrived. They said that "any"
>>wetting agent will build up over time, on your
>>reels, making them difficult to load. Basically, don't put your reels in
>>any wetting agent.
>
>
>I have read this advice many times before and it does not make
>sense.  Photo Flo
>and the other like materials are nothing other than very dilute and highly
>soluble surfactants (soap).


Tom Kachadurian's statement that wash agents and stabilizers are the cause of
reel deposits is astute.  The exact compositions of wash agents are trade
secrets, but their main ingredient is sodium sulfite.  Although sodium sulfite
is water soluble, it will certainly cake up if not rinsed off the reel. However,
I doubt any skilled photographer would allow white chemical deposits on reels go
unnoticed.

Let's return to the discussion of wetting agents.  Wetting agents such as Photo
Flo, which are surfactants, are highly energetic surface agents that greatly
lower the surface tension of water.  A few drops does the trick.  Surfactants
are also excellent lubricants.  For example, motor oils contain surfactants.
Certainly if a wetting agent is allowed to dry on reels it will affect their
surface energy which will change their frictional properties.  However, the
wetting agents used in photography are extremely dilute and are highly soluble.
A good rinsing should be adequate to remove these agents from reels.

For over 25 years I have placed film still on reels in Photo Flo as the final
step before drying and have never experienced a problem from it.  Working with
wet film while off the reel, as has been proposed by several LUG members, is an
invitation to scratching, dropping, collecting dust, or even worse.  I keep wet
film on its reel until I hang it up to dry.

Glen Robinson