“After the plate has been thoroughly rolled in and blackened, it must be rubbed with a piece of unbleached muslin, previously saturated with the following solution: 30 parts of ammonia and oxgall (about equal parts), 30 parts gum arabic, 90 parts water, until the picture develops perfectly clear. Dry with a clean piece of muslin, and roll in for the printing proper with ordinary thin copper plate printing ink. Plate paper, similar to that used in printing from the copper plate, is most suitable.” When printing operations are complete, the rollers, printing plates, and inking slabs should be at once cleaned, as the varnish colours soon harden and create difficulties. =Cleaning Leather Rollers= without damaging them requires considerable practice. They are always scraped with a clean knife, and the operation should be performed in one direction, to ensure which it is advisable to mark one of the roller handles. Leather rollers not in constant use, before being put aside, should have their surfaces carefully and thoroughly rubbed over with tallow, which must, of course, be scraped off before the roller is again used. =Cleaning Composition and Indiarubber Rollers= should not be effected by means of scraping, but their surfaces should be cleaned with turpentine, applied with a linen rag free from lint. =Cleaning the Plates.=—Turpentine is used to free the surface from every particle of ink, and after the thorough evaporation of the spirit, the plates should be well washed in water to remove all trace of the damping solution, dried, and stored in a cool place. It is sometimes a matter of difficulty to remove ink from Collotype plates that have been printed from, but a simple method is to pour over the plate—as in developing a collodion picture—some lukewarm water. This will dissolve a thin layer of gelatine, and enable one to at once proceed with the work. CHAPTER IX. FINISHING AND VARNISHING COLLOTYPE PRINTS.