Digitising the Christina Broom Glass Plate collection

Author: Gemma Cattell, Marketing Executive, Townsweb Archiving

The delicate glass plate negatives are checked before digitisation

The delicate glass plate negatives are checked before digitisation

Christina Broom, the UK’s first female press photographer initially started taking photographs in 1903 to support her family. But the following year a chance meeting resulted in a partnership with The Household Cavalry Regiment that lasted over 35 years. During this time she became The Regiment’s unofficial photographer, capturing a variety of pivotal moments in the history of The Regiment.

Now a unique archive of over 200 glass plate negatives featuring Christina Broom’s work for the unit are held at The Household Cavalry Museum’s archive in Windsor. They are part of a larger mixed media collection documenting the history of the two most senior regiments in The British Army – The Life Guards and The Blues and Royals.

In order to help preserve these fragile and historically important images, in 2015 The Household Cavalry Museum partnered with TownsWeb Archiving to digitise the Christina Broom collection.

The right time to Digitise

Having already worked with TownsWeb Archiving previously to digitally preserve the Museum’s WW1 and Battle of Waterloo photographic collections, The Regiment’s archivist decided to partner with the company again to digitise the Christina Broom glass plate collection.

Dating back to the early 20th Century, the plates in the collection are Silver Gelatine Dry Plate Negatives and are mostly A6 in size, with some up to A4.

The primary reason for digitising the glass plates was to preserve a digital copy of the unique images for posterity and to avoid any being lost as the physical plates degrade over time.

Considerations when digitising Glass Plates

Surface dirt and dust is carefully removed from the plate using a handheld bulb duster

Surface dirt and dust is carefully removed from the plate using a handheld bulb duster

Before digitisation, the glass plates were cleaned with a handheld bulb duster (air blower) to remove surface dirt and dust, which could have affected the quality and clarity of the final digitised images.

With some media it is possible to infrared clean during scanning – removing any ‘noise’ such as dirt and dust. However because of the emulsion used on the plates, this was not possible with the Christina Broom collection.

Due to the age and fragile nature of glass plates they can be one of the most difficult media to digitise. So throughout the project extreme care was needed, especially when handling broken or damaged plates.

Broken plates were a particular challenge. When digitising any broken plates technicians had to carefully place the fragments as close together as possible – to provide as complete a picture as the plate allowed.

In addition, on some of the older plates emulsion was peeling off. Technicians mitigated this by scanning them matte side down, so that the emulsion could lie flat and distortions were minimised on the digital images.

Scanning Equipment and Specification

  • Epson flatbed scanner (set on ‘Transparency’ mode)
  • Hand held bulb duster
  • Bespoke post – processing software
  • Approx. 200 glass plate negatives in the collection (up to A4)
  • Captured at 1200ppi to master TIFF format
  • Captured in Greyscale at 8 bit pixel depth
  • Average TIFF file size – 45Mb

A flatbed scanner set to Transparency mode was used to digitise the collection, mainly because it allowed for the greatest consistency across all images, in terms of colour profile and picture quality.

The high resolution offered by this type of scanner is also more suitable for capturing glass plates, which typically require a greater resolution than loose photographs or bound volumes (see below – File Requirements).

However, in many cases, when digitising glass plates a DSLR camera and light box capture workflow can be used instead.

Once the Museum’s collection had been captured, any blemishes or imperfections on the final images were fixed using bespoke post – processing software. Alternatively, some scanners have software that allows images to be automatically ‘corrected’ during the digitisation process.

Capturing the truest image

Throughout the digitisation, the Christina Broom glass plate collection was captured in 8 bit greyscale. This partially restored the plates to their former appearance and resulted in a greater clarity (due to the increased contrast) in the final digitised images.

Some archivists prefer to capture glass plate negatives in full colour as it shows a true snapshot of the plate at a particular point in time including how it’s aged, fading and any deterioration.

As mentioned, The Household Cavalry Museum’s main reason for digitising was for preservation purposes. For this reason greyscale proved the most suitable technique, as it resulted in the clearest and most useful images for the Museum.

One of the digitised images captured from the Christina Broom collection

One of the digitised images captured from the Christina Broom Collection © Household Cavalry Museum

Digital file requirements

In terms of file requirements, all of the 200 glass plates in the collection were captured at 1200ppi to master TIFF format. Scanning at a higher resolution meant as much tonal information as possible and all the detail from the glass plates was captured. As standard, The National Archives recommend that PPI should be considerably higher for any photographic material, including glass plate negatives.

The master TIFF files were then converted from negatives to positives in post – processing using a bespoke graphics programme.

The last stage in the digitisation process was to produce smaller, compressed JPEG versions from the master TIFF files. These smaller JPEG files make it easier to browse the digitised archive and can be published on the Museum’s website, if required, at a later date.

An historic collection preserved

The digital reproductions of the Christina Broom glass plate negatives are now held at the Museum’s archive in Windsor, safeguarded for future generations. A backup version is also stored elsewhere, as an extra precaution against potential unforeseen disasters.

If you would like to find out more about The Household Cavalry Museum and archive, check out their website. Or feel free to look at the TownsWeb Archiving website for further advice on digitising glass plates and information on glass plate digitisation.