Caring for Treasures

They say a picture can paint a thousand words and from my experience working with photographs, I know this is true. Visual images can provide so much information that the written word just can’t. Images can rekindle memories, and form a link with people or times gone by.

Ashburton Museum houses all kinds of treasures, but photographs form one of the largest parts of our museum’s massive social history collection.

1. Garments, letters, photographs.jpg

While we call them simply ‘photographs’ they come in a variety of shapes, sizes and formats. Dealing with them can be a challenge, because each type comes with its own particular requirements as to storage.

Last June, as part of our Bugs, rust and dust bunnies exhibition, the museum ran two workshops on caring for treasures at home.

The first workshop, called Remembering Your Soldier, demonstrated easy ways to research family members who served. It also covered how to care for and record wartime letters, books, postcards, diaries, and of course photographs.

A second workshop “Fabrics of History” focused on caring for treasured textiles and clothing.

When covering photographs, we first explained how to identify what type of image people have in their collections and second, how best to look after them.

While some issues concerning images are generic – how they can be damaged by changes in the temperature and humidity (‘the environment’ in museum lingo), we also have to understand how the image is made, to fully appreciate how delicate these images really are.

The earliest images we have in the collection are images on tin, called tin types, and on silver, called Daguerreotypes. These images are very delicate and can easily be scratched or broken.

More ‘common’ but just as fragile are glass negatives. Obviously being glass they are easily broken, but they are even more at risk because the image sits on the glass and can be easily scratched. Even dust on the emulsion can spoil the image.

2. billy thomas negative.png

Jelly images and backings

One way the emulsion was made to adhere to the glass was to mix it with gelatine.  If one thinks of these wonderful images as a big jellies, you can easily imagine the problems caused by dampness, causing mould, and how attractive they are to pests, such as silverfish.

Glass negatives aren’t they only photographic images that have food associated with their manufacture. For example, albumen prints were popular throughout the later part of the 1800s. Clever readers will be able to guess perhaps, that the photographic paper was covered egg white. This accounts for the problem many people see that their precious image bubbles then cracks away from the card mount.

3. tintype.png

While the actual ingredients of the image itself causes problems, so too does the ‘media’ – the backing of the photo.  Early images were mounted on acidic card which can leech all sorts of nasties into the image.

Card also absorbs moisture, so damp conditions can see the card bending, which cracks the image.  Paper backing, such as the images we have from the 1930s – 50s, can easily tear, or like the card distort due to heat or dampness.

4. West Street slide.png

More recent images are not immune to problems. Modern images with plastic backings are like a sandwich, made up of different layers.  Placed in too hot an environment and the sandwich filling falls part.

Essentially the filling (the image) slips away from the bread (the plastic backing). This issue can be found in positives but is more dramatic with negatives when the image disfigured by cracking.


It all sounds very depressing and worrying, you could be forgiven in thinking that it’s too complicated a business looking after your images and other treasures, but we are here to help. With a few hints and appropriate storage you can easily and safely preserve this history for the future.

5. Daguerreotype.png


By Kathleen Stringer



  1. Garments, letters, photographs are treasures worth keeping well.
  2. This fine image of two Billy Thomas homes is married by cracking. This occurs due to heat or intense light which causes the cellulose to bend. As the image is made up of different layers, the whole image falls apart.
  3. We don’t know these two young men are, but we do know there image is printed on to tin.
  4. This dramatic image has been taken from a slide. Slides have a number of issues associated with them. They may fade or discolour, and like their glass counterparts are easily scratched or broken.  However, the main issue is that without a slide projector they are had to view. Many of the slides in our collection have been scanned.
  5. Mrs William Turton with her sons John and Edwin are depicted in a true Daguerreotype. Some so-called Daguerreotypes are actually glass plates (called ambrotypes), however, this image clearly shows the tarnishing so common with all silver items.  Both types of images are often found housed in leather or wooden cases and for their protection should not be removed.

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