When you have been all over the picture with the first coat of colour, varnish as before, and proceed with the second and third coats. You must be very careful in varnishing the colours, and not go over them twice. The colours are to be got at all artists’ colour shops. Ask for tubes of water-colours for glass-painting. Some of the larger firms also publish little books on glass-painting, in which you will find many useful hints.
When the colouring of the picture is finished, varnish it all over for the last time, and set on one side to dry. Now cut some squares out of your black paper the exact size of your glasses, and cut from the centre of each a circular hole three and a half inches in diameter; place one of these pieces on each of the varnished pictures (on the varnished side); take, and clean, six other glasses, and place one on each of the paper squares on the pictures; next fasten the two glasses together by glueing a narrow strip of paper all round the edges of each pair, and lapping on to each glass not more than one-eighth of an inch.
When they are quite dry your slides are ready for the lantern, and the pictures being inside between the two glasses, will be protected from injury from dust or scratches. In putting the slides into the lantern the painted glass should be nearest the light, if to be shown through a transparent screen; and the other glass nearest the light if to be shown on to a wall or opaque screen.
Fig. 2
These slides will be too small to use in the lantern by themselves, so you will have to make a wooden slider for them. This is made as in [Fig. 2].
Fig. 3
Take two pieces of board one-eighth of an inch thick, four and a half inches wide, and eight inches long, with a square hole cut in each three and three-quarter inches square. These boards make the back and front of the slider, and are joined together at the top and bottom by two narrow strips of wood eight inches long, a quarter of an inch wide, and one-eighth of an inch thick. This slider is pushed into the slide-stage of the lantern, and the glass slides pushed into it as in [Fig. 3].