Salvage as one of the threats can occur not

Salvage of water damaged photographic materials

 

All conservation
collections, museum or private, face different threats – fire, floods, bio
contamination and so on. Water damage as one of the threats can occur not just
in a case of floods but fire as well, when the fire is extinguished by water.

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 In 1993 Perth Museum and Art Gallery in
Scotland suffered in floods that damaged their collection, amongst it
photographic materials that had to be salvaged. In 2011 Japan suffered
devastating effects of earthquake and tsunami and became first country to deal
with salvage of photographic materials in national scale. Conservators and
volunteers worked together to save family photographs and albums and to return
them to their owners. These are just two examples where photographs are damaged
in floods, there are many more.

 In both of these cases there were photographic
materials that suffered water damage. The difference is in the scale and the
range of photographic media. Where in Japan most of the photographs were commercial
20th century processes like, chromogenic colour photographs on resin
coated and fibre based paper. In Perth Museum and Art Gallery they were glass
plate negatives, Lantern slides and roll and sheet film. Though depending on
museum the variety of the photographic processes can be very broad – different
19th century processes, early colour photographs, contemporary
photographs etc. Every process has different resistance to immersion in water
and every collection has slightly different approach but there are guidelines
how to salvage photographic materials and what actions to take. These
guidelines will be discussed in this essay, along with the characteristics of
photographic prints and how photographic materials respond to immersion in
water.

 

 

Structure of photographs and their response to water

 

There are many
different photographic techniques, that developed and were popular in different
times since photography was invented in 1830’s, but all techniques have the
same laminar structure. The thickest, underlying support most commonly is
paper, glass, metal or synthetic polymer (plastic) that provides physical
support to image. This support usually is covered with transparent layer – a
binder of gelatin, albumen, collodion or other similar binders. This layer
holds the image forming materials, for example metallic particles, pigments,
dyes, and so on (Lavedrine, 2009, p. 6). Though there are some exceptions like
cyanotypes, salt prints and platinum prints that have just two layers, skipping
the binder layer.

Because of the
continuous experiments in the field of photography, the bases for photographic
prints in nineteenth century have been very various – glass, metal, paper.

Paper being most practical and preferred photographic print base, it carried on
and was widely used in the twentieth century. Until the early twentieth century
rag pulp was used to produce photographic paper but because rag paper yellowed
with time, it was important to find another stock to produce paper. In 1929 Kodak started to manufacture
paper from 100% purified wood pulp cellulose, which ensured permanence of the
print. Cellulose, a polymer extracted from plants, is primary component of the
paper and is hydrophilic (Lavedrine, 2003, p. 23-24).

The main alteration in paper when it is
wetted is dimensional changes, when at the molecular level the cellulosic
substrate of paper undergoes structural changes (Bruckle, 2012, p. 423). The
cellulose attracts water molecules and that is the reason why the paper swells.

When paper based photographs get wet, the
paper becomes heavier and tears easily. So extra care needs to be taken when
handling. There are other hydrophilic materials in photographs like, gelatine,
which just like paper expands and weakens in the presence of water and the inks
and dyes that bleed. (Lavedrine, 2009, p. 314)

There are two most
commonly used photography bases since twentieth century. Baryta coated paper,
paper base with one or more layers of gelatine containing a white pigment –
barium sulfate, became widely adopted since about 1885. It is more commonly
known as “fibre based” paper. In 1970’s “resin coated” paper – paper base
sandwiched between two layers of polyethelene – began to be used commercially
and due to its mechanical durability is still preferred base for photographic
prints. It is often referred to as plastic photographic base as well. “Resin
coated” papers compared to “fibre based” paper can be processed trough a machine,
which is much faster process (Lavedrine, 2009, p. 23-26). In a case of
prolonged immersion in water resin coated paper becomes more resilient and is
more prone to mechanical damages, like creases and scratches (Anderson, et. al., 2015).

In the case of Japan’s
tsunami disaster, the majority of damaged
photographs were chromogenic color prints on resin-coated paper printed after the 1970s and those
on fibre-based paper. There were some
gelatin silver prints, negatives and inkjet prints. Because salt, that was
present in the water, is very water absorbent it prevented photographs to dry
quickly. The damage that photographs exhibited were swelling and dissolution of
the gelatin layer, mold growth, photographs stuck to each other or other
materials (Shiraiwa, 2013, p. 197).  Hendriks
and Klaus state that, “gelatin is very absorbent and when immersed in water for
long periods of time, especially at elevated temperatures, gelatin will
continue to absorb more and more water until the structural integrity of the
gelatin layer is destroyed” (1991, p. 432). When the gelatin layer is destroyed
the same happens to the image that it carries. Many aspects, like the nature of
the gelatin, the PH of the water and the temperature, influences how fast the
gelatin layer breaks up (Hendriks
and Klaus, 1991, p. 432). In the
case of the natural disasters, like floods, the water can carry dirt and
organic or inorganic compounds with it and thus not only wetting the
photographic materials but soil them as well, change the chemical structure of
medium, create tidelines when drying unevenly etc.

In museum collections usually there are more varied
photographic materials present, varying from 19th century processes
to contemporary. Every process has different resistance to water; some can’t
withstand immersion at all some handle it better, even up to three to four days
in case of collodio-chloride and albumen prints (Hendriks and Klaus, 1991, p.

424). Although albumen prints can withstand immersion in water and it is even
practiced in conservation to do controlled washing of albumen prints Messier
and Vitale (1994) and Baas, Foster and Trentelman (1999) argued that cracking,
roughness and loss of glossiness increased after washing and drying. Though the
latter authors noted that, the magnitude of gloss loss and cracks, depend on
the thickness of the albumen layer. The authors observed that thicker layered
albumen prints were more prone to stress, compared to the ones that had thinner
layer and were better able to follow the expansion and contraction of the paper
substrate (p. 331). So even amongst the same photographic processes, there can
be different resistance to water and water damage to the object, and, if
possible, individual photographs need to be observed and evaluated for
treatment.

Salvage steps and examples

 

Ideally response
should take within 48 hours; most photographic materials withstand 24-hour
immersion but as explained earlier some can’t withstand it at all. The longer photographs stay in water,
the more deteriorated they will be – emulsions can dissolve or stick together,
paper swell and staining can occur. Water doesn’t affect just the photographic
material, but everything that surrounds it as well. Mounts can separate from
photographs; enclosures can stick to the emulsion. Mould, that often causes
permanent staining, can grow within 48 hours at 60% relative humidity and 21°C,
so the material should be treated or frozen as soon as possible (Albright).

 Most
common treatments after the water disaster is washing and air-drying of the
materials. If no immediate action can be taken, materials should be frozen (Anderson,
et. al., 2015). These treatments were carried out in Perth Museum and Art
gallery, when materials were frozen, then air-dried and then treated. The same
happened in Japan, though every city and organisation had slightly different
approach to the salvage of photographic materials; nevertheless they all used
more or less the same method. Yoko Shiraiwa in an
article Rescuing tsunami-damaged
photographs in Japan explains how rescuing works in Ofunato were carried
out: when the photographs were delivered to the site where they were treated,
they were air-dried first and then washed. These were two main treatments. (2013, p. 198).

Least stable and most valuable materials
should be treated first. If the photograph is too damaged and beyond repair it
shouldn’t be priority. It is important to stay organized and register every
step taken and keep collection in order. Emergency treatment procedure for
photographs collections after flood should be followed (Fig. 3). It helps to
make decisions about the steps that need to be taken depending on the
situations (Lavedrine, 2003).

 

Washing

Ideally the first step that should be
taken is washing and rinsing of photographs but it should be only attempted
when the photographs can withstand it for example, there is no chance of layer
separation and loss of image etc. In the case of floods in Perth Museum just
cotton wool swabs with distilled water were used to clean emulsion side of
glass plates and lantern slides. This was attempted just with photographs that
were in stable condition (Harvey, 2000, p. 19). Preferably the water used for
washing should be cold (18C) and distilled. If it is not possible to distil the
water, freshest available water should be used. PH levels in water can be
adjusted as well (Lavedrine, 2003)

Photographs that have been exposed to
dirty flood or salt waters, and can be safely immersed in water repeatedly,
should be washed and rinsed to remove any water-soluble contamination. Longer
washes remove foreign materials that are more embedded in the structure of the
photograph. Quick rinses help to remove debris that is on the surface, thus
reducing future abrasion. Multiple tray system can be used during washing and
rinsing. Soft brushes, squeegees, cotton balls or dental cotton can be used for
cleaning. Photographs should be placed on support, like glass or plastic
glazing, during the cleaning process and rinsed between each cleaned photograph
to avoid contamination. (Anderson, et. al., 2015).

The process in Japan’s photographic materials salvage case was;
air-drying photographic materials first and then washing them. Because the
quantity of photographs was very large, some were frozen as well. Shiraiwa
describes the most common damages and treatments of the photographs after the
tsunami in Japan: many of the photographs were in albums that stuck to the
photographs and had to be separated. The pocket albums had to be cut along the
rims and placed in the water so the photographs could be removed. More
problematic turned out to be the magnetic albums (self adhesive), where
photographs were adhered to thick card with cellophane cover. Problems that
occurred were, that the water couldn’t penetrate the thick card and the card
had to be split, or the photograph was stuck to the cover sheet, in which case
the photograph was cut out with the card and cellophane sheet attached. Some
photographs stuck to each other and the ones that stuck on to the glazing were
extremely difficult to treat, especially if the prints were on resin-coated
paper, where paper is sandwiched between two polyethylene layers, making it
impenetrable to water. Photographs, that were not in albums, but in piles stuck
to each other when found, had to be immersed in water until they could be
peeled off one by one (2013). Photographs sticking to each other or other
materials, like enclosures, albums, mounts etc., is one of the problems, after
the collection has been immersed in water. Christopher Harvey after the flood
in Perth Museum came across the same problem, when sleeves of glass plate negatives
and storage boxes of lantern slides had to be carefully removed from the
photographic medium to proceed to other treatments, like air-drying and
cleaning. Glass plate negatives that were stuck to each other with emulsion
sides, had to be separated with extra care. Thin needle was inserted between
the plates to release the adhesion between the emulsions (2000, p. 18). In AIC
(American Institute for Conservation) Wiki page it is advised to prioritize
photographs that are stuck to glass. The image can be immersed in water for
easier separation from glass. The photograph shouldn’t be removed at sharp
angle, to avoid cracking in emulsion. In a case when photographs cant withstand
repeated immersion in water, “place release materials
under the areas that are not stuck and place thin spacer material such as
blotter between the glazing and the release material to try to encourage
gradual release and prevent more areas from adhering “. If the photograph
has stuck to plastic enclosure, cut sides of the enclosure and remove the plastic carefully,
laying the photograph flat and peeling the enclosure off in sharp angle. It
should be avoided to pull wet photographs from their protective enclosures (Anderson, et. al., 2015).

In 1983 Hendriks and Lesser reported an experiment where photographic
materials were immersed in tap water, for long period of time, at room
temperature and then dried. Four different techniques of drying were used:
air-drying, freezing-thawing-air-drying; freezing-thawing-vacuum-drying and
freeze-drying. From all drying processes air-drying proved to be the best and
showed least changes in the dimensions of the photograph.

The observations were that paper prints generally shrunk more in length
than width direction. Black and white prints exhibited loss of surface gloss.

The authors speculated that the “filamentary structure of the image silver
undergoes changes during soaking, freezing, and drying to form more rounded out
silver particles which show less light absorption and therefore cause a density
loss” (p.54).

To compare different photographic techniques salt prints, albumen prints
and chollodio-chloride prints survived washing and drying surprisingly well.

Gelatin in these prints, in the circumstances of this experiment, underwent
reversible changes like swelling and de-swelling, softening and hardening.

Gelatin has these properties until it reaches a breaking point of destruction.

Half of glass plate negatives in this experiment didn’t show any resistance to
immersion in water (24h) and lost image layer, the other half that survived was
shattered to pieces during freeze-drying.

Black and white silver gelatin photographs suffered various signs of
deterioration ranging from total destruction to severe mottling of the gelatin
in freeze-dried materials and light loss of surface gloss in air-dried prints.

Although less experimental data on color photographic materials were
gathered, the authors concluded that chromogenic color prints compared to black
and white photographs showed more resistance to immersion in water and drying.

 

Air-drying

Second step, after washing, should be
air-drying. Prints should be naturally
air-dried on blotter paper, image side up or on clothesline, using pegs or
paperclips to hold them. Touching the surface of the image should be avoided (Anderson P., et. al. 2009).

Depending on situation these two steps,
washing and air-drying, can be switched and that is what happened both in Perth
Museum and in Japan’s photographic materials salvage case. Air-drying was
carried out before washing.

 In this case extra care needs to be taken,
that photographs don’t stick to each other or other materials, like albums,
enclosures etc. If they are air-dried this way it can be very hard to separate
them (Hendriks and Klaus, 1991, p. 424).

In Ofunato the conservator Shiraiwa carried out air-drying after the wet
treatments. The resin-coated photographs were hung out to dry on a clothesline
with clothes pegs and fiber-based photographs were pressed between newspaper
and blotting paper with silicone-coated paper, baking paper in this case, on
top of the print surface. The approach, with sandwiching the photographs and
placing silicone-coated paper on print surface is interesting, as it is not
advised to place anything or even touch the emulsion layer.

Later on in
salvaging process Tokyo Document Recovery Assistance Force set up the Air
Stream Drying System in Ofunato. This system relieved drying process as
volunteers could be easily trained to use it, the system could be set up
anywhere and worked great in limited space. Large amounts of photographs could
be dried and flattened at the same time without changing the blotters
(Shiraiwa, 2013, p. 199).

The way this
system works is that a material, corrugated board or synthetic materials with air
channels, is combined around the stack of photographic materials that needs to
be dried. Air-dryer is placed at one end, so the airflow is moving in from one
end and moving out trough the other. The water that is in the treated object moves
along the corrugated board and is carried away and evaporates (Banik, et. al.,
2011).

In Perth Museum glass plates and lantern slides were dried on wooden
drying racks, placed vertically emulsion side up (Harvey, 2000, p. 18).

 

Freezing

In numerous publications it is advised to freeze water-damaged
photographs if they can’t be dried straight away. That allows treating as many
materials as the resources and space allows. Before the freezing it is advised
to rinse any surface dirt, with cold, clean water and then photographs have to be
placed in tightly closed polyethylene bags. When they are ready to be treated,
photographs should be thawed at room temperature (Anderson, et. al., 2015).

Lavedrine suggests as soon as they are unfrozen and flexible, they should be
separated and naturally air-dried (2003, p. 130). Hendriks and Klaus ads that
some of the materials might stick together and in this case they should be
immersed in cold water to make sure, that they don’t dry before they are
separated, otherwise they can stick together permanently (1991, p. 425).

Freeze drying (placing frozen prints in a vacuum for several days) is an
option as well, though Lavedrine doesn’t recommend it, as it may cause whitish
veil on photographs (2003, p. 130) and Hendriks and Klaus note that freeze
drying can result in additional damages such as dimensional changes, density
loss, and changes in surface gloss. Freezing-thawing-vacuum drying should be
avoided at all cost, as the gelatin layers are sticking together permanently
(1991, p. 425).

In Japan photographs that couldn’t be treated straight away were placed
in thin, high-density polyethylene bags and then in the freezer. Photographs
dried gradually in the freezer, which was advantage for further treatments and
in some cases freezing proved to be even better than immediate treatment. For
example after freezing clear cover sheet in magnetic album could be removed
easier from adhered photograph (Shiraiwa, 2013, p. 199). 

 

 

Conclusion

 

All possible measures need to be taken
to prevent threats of damaging collection in a case of flood or minimise the
damage in the case of one. Photographic collection can be very diverse with
different photographic processes. Some processes, like autochromes and glass
plate negatives, are very vulnerable to water damage. Other processes, like
albumen prints can withstand prolonged immersion in water.

In a case of floods or other water
damage in photographic collection emergency treatment procedure (triagle)
should be followed, where first decision to make is which materials to salvage
first and then depending on situation which steps to make or which steps to
make first – washing, air-drying or freezing. It needs to be taken in account
that not all photographic materials can withstand repeated immersion in water
and some will not survive freezing.

As every disaster case is different and
every photographic collection is slightly different, individual approach can be
taken, but main guidelines remain the same.