METHOD OF USING ROLL BURNISHERS.
Roll enamellers or burnishers act on the principle shown in the Diagram, Fig. 413. The prints should be dry, but not bone dry ; the exact condition that gives the best results is rather difficult to convey in words, but the prints, if dried spontane ously in a room of normal temperature, should be fit to burnish in an hour. If the prints are too dry, they will yield a poor surface, tending towards cracking, and if too clamp, will blister and stick to the roller. A lubricator is not used on the prints. The rollers should be wiped occasionally during heating, in case any sweating occurs, which would cause the rollers to rust or the prints to blister.
of no value. Dust the print carefully, and, holding it face down, place one end be tween the rollers, which should be ad justed loosely, and wind through. Now tighten down the rollers until a fair grip, but not sufficient to disturb the face of the print, is obtained. The mounted prints Rub the rollers well with a perfectly clean dry cloth (revolving the handle mean while), then moisten the finger and touch the lower roller. if a hissing noise results,
the roller is too hot ; if the roller simply dries at once, the temperature is correct. Having adjusted the heat by the lever at the left side, test with a trial print that is may now be passed through, once from each end and twice lengthways, and the result should be a high glaze without blisters or other defects. In passing the prints through lengthways, the mounts should, until halfway through, be bent slightly upwards as shown at A (Fig. when the part a should be lifted by the fingers, as shown, thus imparting a slight convex curve to the surface of the print. This curve will afterwards disappear and the prints will lie quite flat, hut if the con vex curve is omitted the prints will after wards curl inwards.