Desensitizing is a process whereby the sensitivity of a plate or film is depressed, so that the development can take place by a brighter darkroom illumination.

At the present time (1943) the following desensitizers are available:
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[wptabtitle]Desensitizers with Dyeing Properties[/wptabtitle]
[wptabcontent]The most popular member of this group is phenosafranine (Pinasafrol, Desensitol), which forms a very effective desensitizer, although it has the drawback of staining the emulsion and fingers.

Stock solution
IngredientQuantity
Mix chemicals in order.
Phenosafranine1gram
Water2liters

For use, dilute with 4 parts of water. Immerse the film in this solution for not less than 1 minute before development.
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[wptabtitle]Coloured Desensitizers[/wptabtitle]
[wptabcontent]Though they are slightly coloured, they do not stain the film. Pinacryptol green belongs to this group.

Stock solution
IngredientQuantity
Mix chemicals in order.
Pinacryptol green1gram
Water1liter

For use, dilute with 4 parts of water, and immerse the film for 2 minutes before development.
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[wptabtitle]Colourless Desensitizers[/wptabtitle]
[wptabcontent]The latest advance in the technique of desensitization is the colourless form, such as:

Pina White:  Dissolve 1 tablet of Pina White in 20 mililiters of warm water. After cooling, pour this solution into 0.5 liters of developer.

Qualitol:  This is sold in the form of a clear colourless solution which is diluted with 20 parts of water for use. Plates or films are bathed in the dilute solution for 2 minutes and then passed into the developer without rinsing. Development can be observed by using an IIford Bright Green Safelight in which a 15 watt lamp provides light. The darkroom lamp should be some 2–2.5 meters away from the developer dish or tank.

Desensitizing Yellow:  It is sold in 1 gram tubes. The contents of a tube, a fine yellow powder, is dissolved in 1 liter of boiled water. When solution is complete the solution is made up to 2 liters with cold water and is then ready for use. Bathe for 2 minutes and then proceed as described for Qualitol.
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