Modelling in some plastic material is the first step in learning to execute work in more solid materials, such as wood and stone. With a plastic substance, such as clay, it is possible to correct errors and introduce improvements while the design is in course of development, and various ideas can be worked out easily and rapidly in a preliminary manner which will indicate very faithfully what the effect would be in wood or marble, papier mache or leather. Moreover, when proper clay is used, the model itself may be baked and rendered permanent.
The room or workshop where modelling is to be carried on should be reserved for that purpose, or a portion of a room may be so used. The floor should either be bare boards or covered with oilcloth. Under a window should stand a firm table, with the light falling on it either in front or on the left side. This table will be surmounted by a slate or stone slab, or by a wooden stand on which the clay is manipulated. A slab is preferable to wood, as being unaffected by the moisture exuding from the clay. When a wooden stand is used, it may take the form shown in Fig. 284. This is made of ordinary deal, the sides being well clamped to ensure rigidity, and a 5 couple of coats of paint or varnish being applied all over as a preservative. The working face a will be much improved by laying a piece of school slate over it. The dimensions of a must in some measure depend on the work in hand, but about 2 ft. from side to side, and 1 1/2 ft. from top to bottom edge are average figures. The height above the floor should be such that the work to be modelled comes level with the workman's face, standing.
A handy accessory to the modelling stand is a miniature turn-table carrying the slate; a piece of board with a pin attached to the back, fitting into the hole in a will answer the purpose, and greatly facilitates getting at all sides of the object under treatment; but it has this disadvantage, that a certain degree of instability is introduced; slate on the modelling stand may be replaced by covering the latter with sheet lead or zinc, anything in fact which will not absorb moisture.
Many workmen employ ordinary blue clay such as is used for making earthenware, and commonly known as kaolin. This may be purchased at the places where it is dug, in Dorset, Devon, Cornwall, etc, or from potters in any part of the kingdom. In large quantities it costs about 3l. a ton; in lesser parcels about 4-5s. a cwt., and in still smaller about Id. a lb. But not less than 1/4 cwt. is of any service, as its weight is disproportionately greater than its bulk. In quality it should be as pure as possible, not gritty, and capable of being freely worked. Colour is no guide, being due to the presence or absence of a small proportion of iron, and varying accordingly from a reddish-brown to a pale-grey tint. When purchased from dealers at about 10s. a cwt. it should be in a fit state for use; but when bought at the pit or from the potter it will be in the rough state, and must undergo a refining process before application.
This refining process consists in very carefully cutting the mass up by means of wires fitted in handles, which will reveal the presence of any coarse or gritty particles. Or it may be subjected to a thorough beating with an iron bar, all foreign matters being picked out as discovered. This must be followed by a kneading process, whereby its consistency is rendered suitable and homogeneous. Suitability in this case means somewhat softer than putty, so that it can be freely and readily worked and formed by the fingers. If it becomes too soft, this .can be remedied by leaving it open to the air for awhile, when it soon loses part of its moisture; if too dry, it must be broken up in water and re-kneaded, unless adding a little water and folding a wet cloth round it will suffice, as it sometimes does. The addition of a little fine sand well incorporated with the mass facilitates the working, especially in large objects.
Having worked the clay into good condition, the next thing is to keep it so, which simply means preventing it from drying. Nothing answers the purpose better than a glazed earthenware pan of a capacity of 6-7 gal., which can be furnished with a wooden cover, and at the bottom of which a little water is put. Here the clay will remain soft for many weeks. Even when not in use, clay should never be allowed to get quite dry, but always put in the pan with water and worked up. The more it is used the better it becomes, getting seasoned as it were. As soon as a model is done with it should be broken down into walnut-sized pieces, very carefully examined for possible impurities, and put to soak at once. The same rules as to moisture hold good in the unfinished or finished model as in the original clay. Without application of moisture the clay will quickly dry, the sequel to which is shrinkage and cracks. The remedy is to occasionally sprinkle the model with water from a brush or spray-bottle while at work on it, and to always keep it surrounded by a moist envelope when not at work on it.
This envelope usually takes the form of calico next the model, and coarser more absorbent cloths outside; and when it is desirable not to allow contact between the envelope and the model, the latter is protected by a slight wooden framework, or by inserting little sticks into the model where they can do no harm, and holding the cloths off by their projecting ends. As an extra precaution, a waterproof material may form an outside covering as it will more effectually prevent evaporation. Changes of temperature should be guarded against, and- especially extremes whether of heat or cold.
Much the same conditions apply to pipeclay as to china clay. It may be obtained of plasterers and pipemakers, the latter being less likely to contain fragments of plaster of Paris, for which it must be carefully examined.
The tools required are of the simplest description and may all be made at home, or purchased from edge-tool dealers. Those made from any hard close-grained wood such as pear, are just as good as more expensive articles in bone or ivory. Fig. 285 is a chisel-shaped tool with a bent point; Fig. 286, a flat blade with one edge smooth and the other serrated; Fig. 287, a double spoon-shaped or bent spatula; Fig. 288, a combined sword-blade and pointed spoon; Fig. 289, an oblique chisel edge and sharply curved spoon bowl; Figs. 290, 291, flat bowls for roughing out; Fig. 292, a combined bent point and toothed blade; Fig. 293, a wire tool; Fig. 294, a toothed rake of brass wire, which may be in several sizes, from 1/2 in. to 3 in. across the edge a. Fig. 295 a handled blade of flattened brass 'wire. All the wooden tools can be easily cut out of pearwood with a pocket knife, and finished with a rasp and fine sand paper. They are mainly destined to replace the modeller's thumb where that cannot be used, and the chief thing to guard against is the occurrence of points or sharp edges. A few odd pieces of pearwood at hand will always enable the modeller to cut a new tool for any particular piece of work in hand. The simplest is the best.
Other necessaries will be a serrated straight-edge about 18 in. long for smoothing backgrounds, a fine sponge, a plummet, a pair of callipers which will embrace the shoulders, and a pair of compasses.
Clay modelling tools.
Clay modelling tools.
Select a very simple image on which to try your prentice hand. Place it at a convenient height level with the modelling table. Prepare a foundation of the necessary thickness, taking great care to work it into a uniform and coherent mass. Level it true with the straight-edge, and place temporary strips of wood at the sides, as a guide. From the mass carve away very gradually, by a scraping motion, from the necessary parts so as to create a broad general resemblance to the selected object, always avoiding taking away too much, and frequently checking dimensions by the compasses and callipers. It will only be after some practice that the eye will be able to grasp the essential features, and detailed work should not be attempted till success attends the efforts made in bolder subjects. The most important point is to so work that the whole operation shall consist in cutting away, and avoid having to build up. Added portions will rarely have exactly the same consistence as the body, and unless very carefully attached will be insecure. Solid objects, such as animal images, busts, etc, will be the easiest to commence on.
Foliage and articles of fine texture are much more difficult to imitate.
The first step in laying the foundation is to accurately sketch the outline of the proposed object on the modelling board, by means of pencil or crayon. Commence with clay that is fully soft, and always avoid retaining it too long in the hand, as it thereby soon dries and loses its cohesion. Work the clay into little rolls and lay it on by holding the roll in one hand and pressing the clay into place with the other. The chisel-shaped tool is employed to keep the clay correctly to the pattern, and the greatest care must be exercised to press it perfectly down and prevent any air bubbles or other impediments to absolute adhesion between clay and board. The foundation must be finished all over before any building up is attempted. This refers, of course, to flat work, such as panels, which are afterwards to be copied in wood. When making additions, it is very essential that both surfaces to be joined should be somewhat softer than the bulk.
Modelling in Wax is better adapted for small objects. The materia] consists of wax slightly coloured by the addition of a pigment and somewhat softened by a solvent. A good recipe is said to be: 200 parts clear wax, 26 Venice turpentine, 13 lard, and 145 precipitated bole, mixed and well kneaded in water. But many prefer to purchase prepared wax from an artists' colourman. The tools used are the same as for clay, but smaller, blunter, and generally of bone. The operation consists in building up rather than cutting down; and the chief precaution is to keep the tool moistened with water to prevent adhesion. Considerable practice with clay is a good preliminary to trying wax.