=Sunning.=—When sufficiently exposed, _i.e._, when the brown picture with all its half-tones and details is complete, the plate is removed from the copying frame and placed, face downwards, upon a piece of black velvet, and exposed for a short time—five to ten minutes—to a good but not direct sunlight, so that it may pass through the glass plate and harden the back of the print layer. A sheet of ground glass may be placed over the plate to thoroughly diffuse the light, and prevent any scratches or damages to the back of the glass plate producing any detrimental effect upon the printing surface. =Washing the Plate= is the next operation. The plate is removed into the dark room and placed in clean cold water, which should be often changed—every half-hour—unless an automatic washing apparatus[I] is used; this is continued until the plate no longer has a yellow appearance, and the picture is visible only as a slight brown image. [I] Jefferies’s Patent “Perfect” Washer is a very suitable appliance, and may be used for Collotype plates, negatives, or paper prints.—TRANS. =Hardening the Film= is effected by soaking it for a quarter of an hour in a one per cent. solution of alum. The plate is again washed, and the surface evenly dried with fine tissue paper, and placed aside for at least two days that it may thoroughly dry. =An Alcohol Bath= is used by many operators to immerse the plate in for half an hour after drying it with paper, perhaps with the intention of drying the film quicker, or to strengthen the layer and assist the formation of the grain, but there is no gain by this procedure, and, as the bath is an expense, it may be omitted. =The Damping Solution=, or so-called etching fluid, is of much greater importance, and it is necessary that the plate be submitted to it before printing be attempted. =Tinted Grounds= often enhance the appearance of prints, and may be imparted to them by the addition of an aqueous solution of red, yellow, or other suitable colour, to the damping solution, which is applied in the ordinary manner. The plate is superficially dried, inked up, and printed from in the usual way. CHAPTER VII. NEGATIVES SUITABLE FOR COLLOTYPE. A Collotype plate may be readily produced from any negative, but the highest results are naturally only obtained when the negative is prepared with a view to its special use. First should be considered the question—May the negative, without detriment to the finished print, be utilised without a reversal? In the not very frequent case of this important point being immaterial, it is simply necessary to produce the negative on patent plate, and it is at once available for printing from. As the negative may easily sustain damage in any of the various operations, it should be thinly and evenly varnished; this, while affording protection, does not mar the sharpness of the resulting print to any appreciable extent.