Ezio : In case you missed my earlier posts.... DO NOT TOUCH THAT EMULSION... it
was made and developed long before hardening fixers were used... the compressed
air could blow it off the plate, the cotton will almost certainly scrape it.. if
you feel you must, try your cleaning on a plate that you can aford to lose...
This from my earlier post....
Ezio: I just did a little checking on Google the search engine (www.google.com)
under the term "glass plate photographic preservation". I got a lot of
references... this is one of them that sums up what most of the other say in
regard to storage and
handling....
Ezio wrote:
> Oh ! Friends ... I am Italian !!!! and thus my family and myself ...
> everybody is drinking carbonated water either industrial either home made
> (I've got all the equipements to inject CO2).
> I have also a micron filter carbon filter active ... to remove all the stuff
> provided by the public water agencies i.e. clorine, atrazine, ddt etc. etc.
> etc. the water in my house is treated through system to remove any
> particular part of CaCO (Carbonated Calcium) producing those white rocks
> inside the pipes and inside some kidneys ...
>
> I was thinking to use truly distilled water and demineralized.
>
> Then I saw many doubts rising ... following your advices and I am thinking
> to use compressed air and very soft material (cotton) only .
>
> I am scared to see the emulsion/gelatine melting down under the action of
> water ...
>
> Sincerely.
>
> Ezio
>
> www.lucenti.com e-photography site
>
> ----- Original Message -----
> From: "Arthur Entlich" <artistic@ampsc.com>
> To: <filmscanners@halftone.co.uk>
> Sent: Monday, March 19, 2001 8:51 AM
> Subject: Re: filmscanners: cleaning neg's, sharpening
>
> >
> >
> > Mark Thomas wrote:
> >
> > > Just a couple of quick comments..
> > >
> > > 1. Cleaning neg's with water
> > > Bear in mind that if you use anything but 'unexposed' distilled water as
> > > a cleaning agent, you are in fact using carbonic acid..!
> > > I used to work in a oceanographic lab, and while checking the pH levels
> > > of a distilled water producer, I was surprised to discover how acidic
> > > the 'pure' water was. The resident chemist gently explained that H20,
> > > when exposed to air, absorbs CO2 and degrades quite quickly to a
> > > carbonic acid solution, of about pH 5.0-5.5 I think. (I'm flying by
> > > memory here - any chemists on the list feel free to correct..)
> > >
> > > Keep that in mind if considering water for cleaning fragile items!!
> > >
> >
> > Well, I think he was giving you a bit of a jest. As you probably know,
> > water is supposed to be neutral, or pH 7. Drinking water, at least here
> > in Canada, cannot be beyond pH 6.5 (it can go alkaline to 8.5).
> > Although it is true that water does absorb minimal amounts of CO2, the
> > pH is not likely to vary much, and the amount of acidity is minimal.
> > However, if you live in an area with severe acid rains, it could get as
> > acidic as a tomato, but this is due to the rain going through sulfur
> > dioxide and becoming sulfuric acid when the rain goes through it. If
> > your water to begin with is fairly neutral, the amount of CO2 absorption
> > to standing water will not do much... if it did, most fish could not
> > survive in it. Soda pop is created by bubbling CO2 through cold water
> > and it has to be kept under pressure in order to keep it there.
> >
> > Art
> >
