Desensitising

from The British Journal Photographic Almanac 1954, p. 263

Desensitisers are supplied, some as stock solutions, some as powders or tablets which are dissolved to form a stock solution. This keeps well if stored in brown bottle. Any of them can be used as a forebath, and except where otherwise stated can be instead be added to the developer. Desensitisers must not be used with certain fine grain, particularly super fine grain, developers. They must not be used with Dufaycolor films, nor with certain brands of panchromatic and super speed ortho materials, some of which refuse to develop after desensitising. Any new material should therefore be submitted to a preliminary test.
[wptabs type=”accordion” style=”wpui-light”]
[wptabtitle]Desensitising Green (Pinacryptol Green)[/wptabtitle]
[wptabcontent](Cloak & Dowdeswell.) (1-gm. tubes.) Stock solution 1:500. Dilute 1:20 for use. Some increase in developing time may be necessary. With developers containing hydroquinone, should be used only as a forebath, but may be added to plain metol, amidol, glycin, and Ilford Certinal developers.[/wptabcontent]
[wptabtitle]Ilford Desensitising Tablets[/wptabtitle]
[wptabcontent](Ilford Limited.) Supplied as Ilford D.S. Green tablets and Ilford D.S. Yellow tablets. Both types are packed individually in Cellophane (like aspirins) in holders containing 10 tablets. Both desensitisers are normally recommended for use as preliminary baths: one tablet of either types makes 3½ ozs. of working strenght desensitising solution. D.S. Green desensitiser can be added to the developer in certain circumstances. It can be added to Cine developers to prevent aerial fog.[/wptabcontent]
[wptabtitle]Johnsons Yellow Desensitiser[/wptabtitle]
[wptabcontent](Johnsons of Hendon Ltd.) A non-staining desensitiser in powder form. Dissolve contents of tube in 20 ozs. of hot water. Use undiluted when cold, as forebath only.[/wptabcontent]
[wptabtitle]Pinacryptol Green[/wptabtitle]
[wptabcontent](Cloak & Dowdeswell.) (1-gm. tubes.) Stock solution 1:500. Dilute 1:20 for use. Can be used as forebath or added to certain developers. Wetting agent may be added.[/wptabcontent]
[wptabtitle]Pinacryptol Yellow[/wptabtitle]
[wptabcontent](Cloak & Dowdeswell.) (1-gm. tubes to make 2000 c.c.s. of working solution.) Used as forebath only. Particularly recommended for use with panchromatic materials and colour film, but see note above. Wetting agent may be added.[/wptabcontent]
[wptabtitle]P.A.C. Desensit N[/wptabtitle]
[wptabcontent](P.A.C. (Photographics) Co. Ltd.) Does not stain, fog, or affect the latent image. For use as a forebath, dilute the stock solution as supplied with four or more volumes of water and bathe the film 30–60 seconds. Can also be added to the developer. For a fast pan emulsion add 20 c.c.s per litre. Green safe light may be turned up after 30 seconds.[/wptabcontent]
[wptabtitle]P.A.C. Desensit P[/wptabtitle]
[wptabcontent]For developing papers in bright light. Add 5 c.c.s. to a litre of developer. After 30 secs. immersion a bright orange light is safe for bromide paper, bright yellow for chloro-bromide, or ordinary room light for contact (gaslight) paper. An acid fixing bath removes any slight yellow stain.[/wptabcontent]
[/wptabs]