Oil and Bromoil 
BromMoiLt.—The most suitable bromide papers for this pro- 
cess are those with fairly thick emulsion films, with smooth 
or half matt surfaces which have not been hardened in the 
manufacture. Many firms make special papers for this work. 
A method of testing paper is to cut a strip, fix, wash, and dry 
as usual; then immerse in water at 25° C. (77° F.), gradually 
raise the temperature, and note when the film begins to feel 
slimy or slippery. This should be between 30° and 35° C. 
(86° and 95° F.); if higher than this, the gelatine has been 
hardened during manufacture, and is unsuitable for the pur- 
pose, or will require higher temperatures for the solutions 
than the usual ones, which range from 24° to 28° C. (75° to 
82° F.). Any developer can be used, though the least suit- 
able is pyrogallol, and the best temperature for development 
is 18° C. (65° F.). The prints should be well exposed and 
development-carried to the limit, that is to say, until there 
is no longer any further accretion of density. The print 
should be rinsed two or three times with water and preferably 
fixed in a 30 per cent solution of hypo, containing 3 per cent 
potassium metabisulphite. Alum or chrome alum hypo baths 
are unsuitable. Washing should be carried out as usual. 
Some adherents of this process insist on the absolute neces- 
sity of drying the prints, while others consider it detrimental. 
The necessity, or otherwise, of this step depends on the 
character of the gelatine; soft gelatines require drying, while 
harder ones can be worked up at once. 
As will be seen from the following tables, there is a wide 
choice of bleaching and relief-forming baths. Those contain- 
ing copper salts are the most favoured. The most convenient 
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