All wooden patterns should be covered with some protective coating so as to prevent warping, due to the moist sand in the mold and to prevent glued joints from coming apart. This coating will give a smooth and glossy finish to the pattern, thus facilitating its withdrawal from the sand. Finished patterns, too, escape much of the rough usage commonly given them by moulders.

In practice there are two general classes of pattern varnishes. The first is composed of Shellac, with or without some coloring indgre-dient. The second comprises the better grades of copal varnishes. Copal varnish gives a better lustre than shellac but it is very slow in drying as well as more expensive, and so will not be thought of in connection with the finishing of our patterns. By changing the color of the shellac varnish, we may distinguish between core paints and the main body of the pattern, and also between patterns for different purposes, as, for instance, pattern for brass, iron, steel castings, etc. Orange shellac varnish is made by dissolving orange shellac in alcohol. The orange shellac comes in thin flakes and may be dessolved either in wood (methyl) alcohol, or in grain (ethyl) alcohol. Wood alcohol is always poisonous, if taken into the system and shellec mixed with wood alcohol is very liable turn to a muddy color, therefore, 1 strongly recommend the use of grain alcohol. Black shellac varnish is made by adding dry ivory black, or lamp black, to the orange shellac. We will use for our work black shellec for the main body of the patterns and the outside of the core boxes, and orange shellac for core prints and inside of core boxes.

First wipe the pattern clean and free from dust. The first coat of varnish should be fairly thick, applied smoothly, and allowed to soak thoroughly into the pattern. When this coat has become thoroughly dry, the pattern will feel rough, because the varnish has hardened any little projecting particles of the wood. This first coat should be rubbed smooth with a well worn piece of fine sandpaper, being careful not to cut through the varnish. Having wiped the pattern free from dust, apply a second coat of varnish, somewhat lighter than the first. This coat, when dry, is again rubbed down, and a third coat applied, three coats being usually enough to render the pattern impervious to moisture.