[rollei_list] Re: Old film
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Sat, 28 May 2005 17:10:00 -0700
----- Original Message -----
From: "Ardeshir Mehta" <ardeshir@xxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Saturday, May 28, 2005 4:32 PM
Subject: [rollei_list] Re: Old film
>
> On 28-May-05, at 5:39 PM, Max Weisenfeld wrote:
>
>> Recently, there was a thread about old film. Here are a
>> few scans
>> from my Father's negatives. They were shot in 1947,
>> 1950, and
>> 1951. Although he used Kodak chemistry, I do not know
>> precisely
>> what. As you can see, they are in quite good shape.
>> These are new
>> scans.
>>
>> http://www.leica-gallery.net/max3/folder-7973.html
>
> Nice pics.
>
> Remember, though, that these pictures are B&W,
> silver-based. The
> image, once developed, is pure silver. Silver doesn't
> deteriorate
> over time AFAIK. (Does it?)
>
> Cheers.
Unfortunately, it can. The silver image can tarnish just
as silverware does. The tarnish is either silver oxide or
silver sulfide. If film or paper is not properly fixed and
washed there are other things that can happen beause of the
decomposition of the residual chemicals. Degradation of even
well processed images is common due to atmospheric polutants
or polutants emitted by storage containers. Peroxides and
sulfur compounds, both produced in quantity by burning
fossil fuels are a primary source but even something as
obscure as the fumes from a fresh paint job in a room can
attack the iamge.
Very considerable protection is obtained by toning with a
sulfiding toner. Other toners that are effective are
Selenium, if there is enough toning, and Gold toners. Gold
and Sulfiding toners are commonly used to protect microfilm.
Photographic materials vary considerably in their
vulnerability to polutants. The least affected are coarse
grain negative materials, the most vulnerable are very fine
grain materials like microfilm and some scientific films,
and warm tone printing paper.
There is a very extensive literature on image permancence
and how to obtain it.
Chromogenic film has another set of vices because the
image is composed of dye. A great many dyes are not stable.
Much of the research in color photography over the last
fifty years has been in the area of making the images more
stable. The choice of dyes is limited if they are to be
compatible with the chromogenic color system. A wider choice
is available if the dye is indenpendant of the emulsion. It
is for this reason that Technicolor prints are so stable.
Many Technicolor prints from the late 1930's still look
about as they did when new but are probably not projectable
due to degradation of the nitrate support. The same is true
for old prints made by the Kodak Dye Transfer process, which
could use more stable dyes, and for color carbon prints
which used pigments rather than dyes.
Silver is more stable than dye but is actually not very
stable unless toned. Silver sulfide is extremely stable.
Silver sulfide images are the result of using any of several
Sulfiding toners, often called Sepia toners. Kodak Brown
Toner and the very similar Agfa Viradon are examples of such
toners.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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