The Photos

The Harrow Photos collection is a collection of glass plate negatives ranging in size from 3x5 right up to 12x16.

The science

The glass plates are 'dry gelatin plates' (silver bromide held in gelatin). Developed in 1871 and replacing the 20 year old Collodion technology the gelatin plates allowed the photographer a much simpler process.

Take the plate, insert it into camera (in its holder), pull out holder slide to reveal plate - now ready for action. Then uncovering lense and recovering it provides the exposure time. Close the plate slide and the exposed plate is now sealed back in its holder and can be taken back to the lab to be processed.

No longer did the photographer have to prepare the plate in the field and then process it immediately afterwards the process became very much more convenient... this lead to an increased ability to take photos outside the studio and is undoubtedly the key factor in the collection having so many photos of the surrounding area.

Archive

The technology is very stable - the glass plate base is strong and sound, and the coating stable. Main issues for the photos are:
- impact damage (cracking / dropping / etc.) storing photos flat is okay, but stored on edge they are fine. The fact that many of these photos have sat in piles filling industrial shelving for 20+ years with no issues is testament to their strength...
- damp / humidity - excessive damp or humidity is not good for the photos, though they have far better tolerance than some other archive materials, however stored in a room which is humidity and temperature controlled within relevant parameters means that little damage occurs to them.

Sizes

3x5 inch (few)

4x6 inch (c. half the collection)

8x6 inch (few)

10x12 inch (c. half the collection)

12x16 inch (6 slides)