SPECIAL PRINTING PROCESSES 501 



water produces greater swelling than cool. In some cases, it may not be feasible to 

 complete inking at one sitting, in which case the print maj^ be dried and resoaked for 

 further inking. But a print cannot be swelled to a lesser degree the second time 

 th\n was done at first; i.e., if the first soaking water was used at 100°F., for example, 

 and after drying the print is resoaked at 70°F., the second swelling will be as great as 

 the first one. On the other hand, if the second swelling is done at 110°F., a greater 

 relief will be obtained than at first, and any subsequent soaking at a lower temperature 

 will produce the same relief as though done at 110°F. This is an important point to 

 bear in mind, since obviously it furnishes an additional means of control and at the 

 same time limits, to some extent, the possible variations in the matter of inking. 



The Brushes. — Special brushes are required for the inking operation, these being 

 made either of polecat or fitch hair or of hog bristles. The last is used chiefly for broad 

 effects or for the first application of ink, the others for finer work or for smoothing out 

 the rather coarse texture given by the bristle brush. It is advisable to have several 

 brushes of different sizes, ranging from 3^ to IK in- diameter, for different purposes; 

 and they should be of the type in which the hairs are cut slanting and are domed, the 

 square-cut brushes being less flexible in use and more likely to tear the gelatin. 



The brushes must be thoroughly cleaned after use; the ink should not be allowed 

 to dry in them. There are two ways of cleaning them. The method preferred by 

 most workers is to wash them with gasoline or carbon tetrachloride (which is sold under 

 the trade names of Carbona and Energine Non-inflammable Cleaning Fluid, as well as 

 sundry others). The writer prefers to wash his brushes with Castile soap and water, 

 for two reasons: (1) he feels that this is less likely to take the spring out of the hairs 

 (this is a debatable point) and (2) frequent applications of water tend to keep the 

 setting of the hairs more fully swelled, so that the brush is less likely to shed. It is 

 true, however, that a brush cleaned with gasoline or carbon tetrachloride can be used 

 again sooner than one washed in soap and water, since the latter usually takes several 

 days to dry satisfactorily. 



The brushes should be kept in cones of stout paper to preserve their shape and 

 should be hung up, bristles down, when not in use, though this last is not imperative. 



The Inks. — These are oily inks, much stiffer than ordinary printer's ink, and are 

 sold especially for oil and bromoil work. The two best known are the Drem and the 

 Sinclair, the former having a wax base, the latter an oil base. There does not seem to 

 be any choice between them, so far as results are concerned; which to use is a question 

 of individual preference. 



Another ink which works as well as those mentioned (though differently) and is 

 vastly cheaper than either of them is that sold by the makers of printer's inks under the 

 name of Stiff Litho Ink. This is somewhat softer than the bromoil inks and requires 

 greater swelling of the gelatin, but, if properly handled, it gives results equal in quality 

 to the more expensive article. This matter of cost, however, is not important unless 

 much work is to be done, since a 50-ct. tube of bromoil ink will give a great many 

 prints, only a very small quantity being required for one inking. 



The inks may be obtained in a number of different colors, though, as in gum print- 

 ing, the rational worker will confine himself to neutral, warm, and cool blacks and 

 various browns. Sinclair makes two warm-black inks, known, respectively, as Encre 

 Machine and Encre TaUle Douce, the latter being a relatively thin ink which may 

 either be used alone or may be mixed with stiffer inks to thin them down for special 

 purposes. 



It is well to have some thinner available, but there is no need to buy the special 

 bromoil thinner. A small bottle of linseed or olive oil is perfectly satisfactory, the 

 amount taken up on a broom straw or a large pin being usually enough to add when the 

 ink must be thinned. 



