For chalk and limestone, mix plaster and sand with the whiting and lay it on thickly, not throwing on sand, as a final operation. Colours, of course, are different here, more bright and light green predominating; but the colouring of the rockwork, etc.., to imitate the various kinds of rocks required, is only to be learned by experience; in point of fact, to colour rocks in an effective manner is really the work of an artist, for it is requisite to know the properties of colours, and to "scumble" and "stipple" or "glaze" one colour over another to get "depth." A few hints may, however, help out the tyro.
For rough sea rocks, after sanding and glueing, go over the rockwork with a mixture of chrome yellow and Prussian blue, mixed with oil and turps, the blue predominating; touch up the points with white, and allow it to dry. The next day deepen the shadows with Brunswick black, "stippling" lightly the remainder of the rock with the same. Arrange sea-shells and sea-weed, here and there, where the mounted subject allows of this treatment. This is a shining dark bluish-green and brown rock, suitable for sea-gulls, divers, etc..
For rough grey land rock, paint over all with lamp-black in powder, mixed with plaster of Paris, and touch up the points with oil white. When the work is quite dry, go over all with a glaze of Prussian blue mixed with Brunswick black. Fit up with ferns, grass, and golden lichens on the points, or in the hollows. This makes a greyish rock with no gloss, and is suitable for owls and similar birds.
For rough sandstone rock, paint over with chrome yellow and a very little blue mixed with oil white, the latter predominating; dust over on the points with red sand, touch up the hollows with Brunswick black, suffer to dry, and then go over all with a very little rose pink or vermilion, worked up in turps with a little varnish. Fit up with ferns, grasses, and mosses. This is a reddish-yellow rock, suitable for anything not having red or yellow fur or feathers.
The predominating colour may be mixed with the whiting, etc.., to paint over the artificial rock; but there is a certain loss of brilliancy in the colours which follow, unless a white ground has been previously laid on.
For certain objects a great advantage is obtained by making up the rockwork on a false bottom and slipping it, ready finished, into the case.
There are hundreds of other varieties, but they must be worked out by each person according to his proclivities. It might as well be expected that a picture could be painted from printed directions as to imagine that one person could make a rockwork precisely similar to another without seeing it done, or without working it out by his own experience.
Trees for large groups may be carved out of successive layers of peat, or modelled up with brown paper and virgin cork; better still by arranging brown paper over rods or a wire framework, covered previously by tow, and afterwards coloured to nature. The leaves of some trees dry and colour up well, and can be introduced on the natural or artificial twigs.
TWIGS. — Artificial twigs can be made by twisting tow round wire, glueing, and throwing on sawdust, peat-dust, etc.., and afterwards colouring. The most natural way, however, is to rub up the gold and grey lichens, and throw them on the glued tow, filling up afterwards with larger pieces to break the lines. Natural and artificial twigs mix well together; the latter, from their flexibility, allowing of any treatment.
FERNS, GRASSES, ETC., FOR "FITTING up." — Time was when our ancestors were content to stick their preserved specimens in boxes with nothing to break the blank of white paper which backed them up. Nowadays we have arrived at such a pitch of decorative art in taxidermy, as in all things, that this stiffness of outline does not suffice; accordingly, we break our background by flowing lines of beauty, produced by the graceful aids of dried ferns and grasses, twigs of trees, etc..