Conservation and restoration of photographic plates

This emulsion layer sits upon what is called the support, which can be paper, metal, film, or, as in the case of photographic plates, glass.

Glass plates emerged as a common support medium for photographic negatives from the mid-nineteenth century to the 1920s.

The fix bath will ensure that the remaining silver halide crystals are no longer sensitive to additional light exposure, removing all excess.

Structurally, collodion wet plates are held together with a specific emulsion type, made using a silver halide mixture in gelatin.

Increasing RH can cause deterioration of other elements; these include the silver halide, varnish, and glass support.

[12] Much like RH, temperatures must be precise and closely monitored for the correct storage of photographic glass plates.

A safe temperature to keep glass plates is 65 °F (18 °C); however, a fluctuation of +/- 2 °F (−17 °C) would not cause a significant impact, making the safest range 63 to 67 °F (17 to 19 °C).

Dissociation typically results in overtime from an ordered system falling apart due to lack of routine maintenance updates or from a catastrophic event leading to data loss.

Ensuring glass plates are locked and stored where only designated museum staff can access them is the best preventative measure against theft.

In the 1990s, The United States National Archive began to notice that some glass plates featured in their collection, on the non-photo bearing side of the scale, a crystalline deposit, known as sick-glass, was present.

[17] Other sources of air pollution include "photocopying machines, construction materials, paint fumes, cardboard, carpets, and janitorial supplies".

The heat produced by a fire can aid in increasing the chemical decomposition rate of the plate's emulsion.

The effect of "sick glass" can be weeping and crizzling caused by excessive alkali and a lack of stabilizers.

For instance, the silver image layer could undergo oxidative deterioration, leading to fading and discoloration.

Types of breakage:[12] Environmental controls are a crucial part of the preservation of photographic glass plates.

Relative humidity (RH), temperature, and light play a significant role in keeping the multiple materials in photographic glass plates maintained.

The vertical assembly method along with a light line is used in The Glass Plate Negative Project at the Heritage Conservation Centre, as outlined in the case study.