498 HANDBOOK OF PHOTOGRAPHY 



Disadvantages. — As has been said, oil is a contact process, demanding an enlarged 

 negative if large prints are to be made. 



It is somewhat laborious. 



It does not render the delicate gradations of the negative as finely as do some 

 other mediums; for this reason, it is not so well adapted to sunny snow scenes, high- 

 keyed portraits, and the like, as platinum, carbon, gum. or Fresson, but is at its best 

 when broader effects are desired. 



The advantages and disadvantages of bronioil are the same as those of oil, with the 

 following exceptions: (1) large prints can be made without the use of an enlarged nega- 

 tive and (2) it is a much more tricky and temperamental process. The first argument, 

 however, is scarcely a valid one, since fully as much labor and skill are required to 

 make a bromoil print as to make an enlarged negative and a platimun print. 



The Paper. — This should be a bromide paper having a soft gelatin emulsion, with- 

 out a supercoat of gelatin. The same paper should be used for both oil and bromoil, 

 since the best oil paper results from fixing, without exposure to light, a sheet of heavily 

 coated bromide paper. This fixing should be done in plain, not acid, hypo, since it is 

 necessary to avoid anj^ hardening of the gelatin. 



Suitable surfaces of Velour Black will be supplied by the Defender Photo Supply 

 Company, of Rochester, N. Y., provided that the order specifies "for bromoil," and 

 the Kodak Royal Bromide, obtainable from the Medo Photo Supply Corporation, 

 15 West 47th St., New York City, can be recommended when a buff stock is desired. 

 There are numerous other good bromoil papers, most of them, however, originating in 

 England, where the process is more popular than it is in this country. 



Whatever paper is used, it should be as fresh as possible. 



The Negative. — For either oil or bromoil, the negative should be soft and well 

 graded, since it is very easy to secure anj^ desired degree of contrast, and a relatively 

 soft original print will render the gradations better than a stronger one. The best 

 type of negative for either process is one which will give a moderately soft enlargement 

 on an ordinary medium-contrast chlorobromide paper. As in other printing processes, 

 a thin negative is preferable to a dense one, for a given degree of contrast. 



Sensitizing for Oil.- — -Having been fixed, washed, and dried, the paper is sensitized 

 by 3-min. immersion in a solution of potassium bichromate and is hung up to dry in 

 the dark. Sensitizing may take place in any ordinary room, since the paper is not 

 sensitive to light until dry. 



The normal strength of sensitizer, for average results, is a 2^2 per cent solution, 

 but it may range in strength from }yi oi 1 per cent to 5 per cent, the stronger solution 

 giving a quicker printing film and less contrast. 



Printing for Oil. — For either oil or bromoil, the paper should be masked so as to 

 give a blank margin at least 3^2 i^- wide — and 1 in. is better — all aroimd the 

 picture. 



Sensitized oil paper should be printed as soon as dry, since it does not keep well. 

 If this is not possible, it should be stored in a sealed airtight box, with calcium chloride 

 as a desiccator. Even so, it will not keep in good condition for more than a very few 

 days. 



Printing is carried out by sunlight, carbon arc, or mercury-vapor arc and should 

 be continued until gradation is elearlj^ visible in the high lights. The print has much 

 the appearance of an undeveloped platinum print, though somewhat deeper; in each 

 case, the image shows as a yellowish brown on a yellow ground. 



After exposure, the print should be washed immediately in water at approximately 

 room temperature until the free sensitizer is completelj^ washed out, when it may be 

 either soaked in warmer water (if necessary) and inked at once or allowed to dry and 

 soaked and inked at some future time. It is not well, however, to postpone the soak- 



