May 2001
President's
Message
Portrait of Helen Sophrin
Photo FAQs
Photo FAQs
Eric Kissa
Below are some of the questions
asked at the "Experts" session, answered now in more detail.
Q.:If
ambient humidity is not a problem, is there any danger from leaving slides
in the cardboard or plastic boxes provided by the processor?
A.:Not
for a short term storage. However, for archival storage the confined space
of the small box filled with slides presents two potential problems: (a)
inadequate access of air needed for the prevention of fungus, and (b)
trapped vapors emitted from the slide mounts or the processed film. The
film (the emulsion side) and the cardboard slide mounts are hygroscopic
and in a confined space the humidity may be higher around the slide than
the humidity in the room where the boxes are stored. Kodak is planning
to replace the conventional cardboard mount with a hydrophobic one and
has mailed samples to some photographers to get their opinion. One of
the mounts is a plastic one similar to the mount used by the Buckley Lab.
The other one looks and feels like a plastic coated cardboard mount. Either
of the two mounts will be a significant improvement.
Although I have not made a
controlled study of the stability of slides stored in various containers,
some subjective observations can be made:
(a) Metal slide boxes, no plastic liner, two slides stored in one slot.
Kodachrome slides stored for 40 years have not changed noticeably.
(b) Metal boxes, group file, with a plastic liner: Kodachrome, Ektachrome
and Fujichrome slides have not changed noticeably in 10 years. The effect
of the plastic liner on fading is of concern but I do not have longer
term data.
(c) Polypropylene slide pages (Century EZTL2C-00, Phone 800-767-0777).
Kodachromes have not faded noticeably in 17 years and Ektachrome and Fujichrome
slides in 10 years (no longer term data).
(d) Carousel slide trays. Kodachrome slides on most of the trays have
not changed significantly in 20 years but have faded noticeably on some
trays. Although Kodachrome slides are less stable to light than the recent
Ektachromes, the number of projections does not seem to have affected
dark storage. One of the possible factors to be considered is the slide
tray and its box itself. The slides had been stored on different trays
and boxes. Kodak has changed the Carousel trays and their boxes from time
to time. One of the boxes was cushioned with a foam rubber sheet which
had deteriorated and caused substantial fading of the slides. (e) Original
cardboard boxes (Duplicates and less valuable slides were left in original
cardboard boxes). The results are mixed. In 10 years, most of the Kodachrome,
Ektachrome, Agfachrome, and Fujichrome slides have not faded noticeably
in their original boxes. In 20 years even some Kodachrome slides have
faded significantly. Many Ektachrome slides have faded considerably, whereas
some have not changed significantly in 17 years. It seems that other factors
such as the processing conditions, the initial condition of the slides,
and the number of slides in the box may have affected fading in the original
box.
Conclusions:
Metal slide boxes and polypropylene slide pages have preserved the slides
well. Original cardboard boxes provided by the processor and Carousel
trays are less reliable for a long term storage, even in a house with
central air conditioning.
A CD is the most reliable archival storage medium, although not absolutely
safe. Storage on CDs is ideal if the images are used for printing or for
a visual display on a monitor. However, a slide regenerated from a CD
is not going to be the same as the original. It may be better but not
exactly the same.
Q.:Dyes used in color slides are known to change in time. How long does a color slide last when stored in the dark?
A.:Fading
of slides during dark storage is a complicated process affected by several
factors: the film, processing conditions and storage conditions. Kodachrome
is processed by the special K-14 process and the slides are stable for
at least 40 years, if properly stored. The other color reversal films
are processed by the common E-6 process. The slides are less stable because
an excess of color forming chemicals is left in the film. The old Ektachrome
64 slides have turned red regardless how they were stored. Fortunately
the stability of E-6 type color slide films has been greatly improved.
However, the stability of slides processed by the E-6 process is affected
by processing conditions and is therefore not as reliable as that of the
Kodachromes. Undoubtedly, Kodachrome is by far the most stable color film
under dark storage conditions. It is advisable, at least occasionally,
to use Kodachrome film (or a silver based black and white film) for photographing
children or grandchildren. Kodachrome KM (ISO 25) has been discontinued
but Kodachrome KR (ISO 64) and the grainy KL (ISO 200) are still available.
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Send questions concerning photographic
equipment (cameras, lenses, accessories, filters), photographic techniques
(other than digital), and film, as well as information on international
photographic exhibitions, to: ekissa @aol.com.