Plaster

“ Plastering is also carried to a perfection in Italy, of which we have very little idea in this country; rooms are so exquisitely finished, that no additional work in the shape of house-painting is required; but the polish of the plaster, and its evenness of tint, are such as to rival those of the finest porcelain. Sometimes the plaster is fluted, or various designs are executed in intaglio upon it, in the most beautiful manner. ”

“ Casting in plaster. This is a mode of copying applied to a variety of purposes: to produce accurate representations of the human form—of statues—or of rare fossils—to which latter purpose it has lately been applied with great advantage. In all casting, the first process is to make the mould; and plaster is the substance which is almost always employed for the purpose. ”

“ Plas′tering, the art of covering the internal faces of walls, the partitions and ceiling of a building, with plaster: a covering of plaster: the plasterwork of a building; Plas′ter-stone, gypsum.—adj. Plas′tery, like plaster, containing plaster.—Plaster cast, a copy of an object got by pouring a mixture of plaster of Paris and water into a mould formed from the object; Plaster of Paris, a kind of gypsum, originally found near Paris, used in building and in making casts of figures; Porous plaster, a plaster for application to the body, full of small holes, which prevent it from wrinkling. ”

“ Plaster moulds were also used for moulding pottery lamps. The oiling of plaster was done on painted plaster statuettes, so as to make them waterproof. They can still be scrubbed in water without disturbing the colour.
The most artistic use of plaster was for the modelled heads, which were placed on mummy cases in Roman times. Though most such works were rather crude, some are found which show real ability of portraiture. In fig. 135 we have a sympathetic study of the face of a young man. The lips are beautifully true, the modelling of the cheek is quite natural, the nose and brow well formed ”

“ Plaster-casting in General
It is not a difficult matter to reproduce in plaster almost any object that has no undercut or parts that will not easily detach from a mould. When making them, the first thing to do is to get a piece of board about a foot square; that is to work on, so as not to soil the table. Then you want a lump of clay about as big as a football, five or six pounds of plaster of Paris—it only costs three cents a pound—and a half-dozen wooden pegs. ”

“ Plaster, or stucco, is sometimes regarded as an inferior material only to be used when nothing better can be obtained. It should not however be judged from the achievements of the domestic plasterer of to-day, who has to trust sometimes to the wall-paper to keep his stuff from crumbling away. Plaster as used by the ancients, and through a good part of the mediaeval and Renaissance periods up to the eighteenth century, is a fine material, susceptible of very varied and effective artistic treatment. ”

“ The part where the artist decides to begin his work is uncovered, that is to say, a portion of the paper is turned down and cut away, but in such a manner that it may be replaced. Then the plasterer puts fresh plaster, about an eighth of an inch thick, upon the uncovered portion of the wall, and the plasterer’s work is of the utmost importance in fresco painting. ”

“ Some skilful painters can stipple one tone upon another so as to produce the same brilliant softness of effect, and when this can be done, oil-colour upon plaster is the best of all treatment for bedrooms since it fulfils all the sanitary and other conditions so necessary in sleeping-rooms. The same effect may be produced if the walls are of rough instead of smooth plaster, so that the small inequalities of surface give light and shadow as in textiles; upon such surfaces a pleasant tint in flat colour is always good. ”

“ IT IS THEN POURED PROMPTLY into the center of the space on the glass prepared for the plaster tile so that the poured plaster gradually spreads from the center toward the corners and edges filling up the spaces and coming up the sides to about one-half inch height. Jarring the table or a slight shaking of the glass will cause the plaster to settle very level as well as causing any bubbles in the plaster to rise to the surface and break. Care should be taken that the plaster is not too thick before being poured. ”

“ The naturalists and their followers, thinking they can solve this question, are like plasterers set to plaster one side of the walls of a church who, availing themselves of the absence of the chief superintendent of the work, should in an access of zeal plaster over the windows, icons, woodwork, and still unbuttressed walls, and should be delighted that from their point of view as plasterers, everything is now so smooth and regular. ”

“ By a method of working in ordinary oil colours on a ground of fibrous plaster, using rectified spirit of turpentine or benzine as a medium, much of the quality of fresco or tempera may be obtained, with the advantage that the plaster ground may be a movable panel.
There are, however, other fields for the decorative painter than wall painting; as, for instance, domestic furniture, which may vary in degree of elaboration from the highly ornate cassone or marriage coffer of Mediæval Italy to the wreaths and sprays which decked chairs and bed-posts even within our century. ”

“ All the fine plaster with which the walls of the houses are covered in India, and which is so much admired by strangers, is composed of a mixture of fine lime and soapstone, rubbed down with water: when the plaster is nearly dry, it is rubbed over with a dry piece of soapstone, which gives it a polish very much resembling that of well-polished marble. ”

“ When the newly introduced plaster is set the mould is carefully knocked away with chisels, and a true cast appears beneath, giving an entire fac-simile of the original model. Some skill is required in making moulds, in order to provide for projecting parts and under-cuttings; practice alone can teach the artist how to deal with those difficulties when they occur. The above general instructions sufficiently explain the ordinary processes of moulding and casting in plaster. ”

“ Still earlier specimens of the plasterer's skill are extant in the pargeted and ornamented fronts of half-timbered houses With regard to the smaller buildings, comprising small dwelling-houses and cottages, the general application of plaster is of comparatively late date, for wainscoted walls and boarded ceilings or naked joists alone are frequently found in houses of not more than a century old both in England and on the Continent. ”

“ Painted plaster-work, so long as water can be kept from percolating through the cracks or faults, or gaining entrance from above by filtration, or from below by capillary action, is a highly durable material, but the moment water gains a footing the lime in some degree is dissolved, and, upon being removed and redeposited, undergoes the process of recrystallization, a powdery substance is thus formed that comes as a stranger between the paint and the plaster, in which respect it bears a strong resemblance to rust, the result of the oxidization of iron. ”

“ The sculptor invariably goes over his plaster cast with utmost care, not only repairing any defects in the moulding, but defining more accurately the hair, finger nails, folds of the drapery, and outline generally, and, above all, perfecting the facial and general expression. These plaster of Paris models are known in commerce and in art as 'casts of sculpture.' They represent the artist's right and title to his creation, and unlike the merchandise in question here, are not painted and decorated, nor dealt in as ordinary commercial articles. ”

“ Modern facilities have greatly abridged the personal labor of the sculptor in marble or bronze. The present method of casting in plaster, which was then unknown, or at least unpracticed, enables the sculptor of our days to elaborate his work to the utmost finish, in its full size, in the clay model; and when this is completed and cast in such a permanent material as plaster, the workman has an absolute model, which he may, to a certain extent, copy with almost mathematical accuracy. ”

“ Scrape the plaster to a level surface, and cut two moderately large V-shaped nicks, one on each edge of the mould, build up around as before with wood, and fill in all interstices leading to the table below with clay. See that the mouth is properly shut, introducing a little clay if needed. Brush over with soft soap, not forgetting the top of the plaster mould, and mix some more plaster and pour over the lower jaw, on to the edges of the plaster mould, until stopped by the wall; build up thicker in the centre, as before, and suffer all to dry for about an hour. ”

“ Most of the supposed medicinal plasters are in the same class. As a rule, sufficient curative material cannot be incorporated in a plaster to be of any service, and most of them, though widely advertised, are scarcely more than rubber adhesive plaster. ”

“ Cleaning Of Statuettes And Other Plaster Objects.—Nothing takes the dust more freely than plaster objects, more or less artistic, which are the modest ornaments of our dwellings. They rapidly contract a yellow-gray color, of unpleasant appearance. Here is a practical method for restoring the whiteness: Take finely powdered starch, quite white, and make a thick paste with hot water. Apply, when still hot, with a flexible spatula or a brush on the plaster object. The layer should be quite thick. Let it dry slowly. On drying, the starch will split and scale off. ”

“ In fresco painting a damp plaster ground is prepared on the wall, upon which the moist colors are painted. These colors become fixed as they dry, and appear to be a part of the wall. The work must be done while the plaster is damp, so the painter prepares only that part of the wall which he expects to cover that day. As it cannot be used after it is dry, he must scrape away all that is left and prepare a new background the next day. If the artist wishes to change any part of his picture, he must scrape off the ground and repaint the entire picture. ”

“ The rough plaster wall, tinted, is the cheapest method of all to use in decoration and has numerous advantages. It is much to be preferred to smooth plaster in that it gives a slight unevenness of surface which is a distinct advantage because of the vibration of color thus attained. Water color, while it does not last as long as oil paint, is so much cheaper and quicker to put on that it becomes possible to do over a gallery after a year or two without any more outlay than oil paint in the beginning would have necessitated. ”

“ They deserve a detailed notice because they prove, as do most Moorish works, that plaster may be used truthfully and artistically, and that without any approach to the contemptible effect which the imbecility and dishonesty of the nineteenth-century designers of plaster-work have contrived to impress on almost all their productions. ”

“ My attempt is seen under every disadvantage; it is too near the eye and too near the light; and it is painted on a material which is most ungracious for the reception of colour. The minute undulations of marble always lose something in a plaster reproduction, but when the plaster has further to be painted with four coats of oil paint to stop the suction, it may readily be imagined how much the more delicate modulations of the surface will suffer. ”

“ Very pretty decorations on plaster may be executed by combining hand-worked illumination with diapered or other paper-hangings. Thus, for instance, taking one side of a room, say about eleven feet high, to the under-side of the plaster cornice, mark off about a foot in depth on the wall from the bottom of the cornice, set out the width of the wall into three or more panels, dividing the panels by upright pilasters of the same width as the depth of the top border. At the height of about four feet from the ground mark off the top edge of another horizontal band, which make also one foot deep ”

“ If the plaster sticks to the end of the rammer, it shows, either that you have used the plaster too wet, or have not turned the rammer round a sufficient number of times.
No more plaster must be mixed at a time than will suffice for one case. When plaster has once set, it cannot be mixed up a second time; therefore take a fresh piece of paper, and let the knife be cleaned every time. It is advisable to have two dessert-knives, then one can be used with which to scrape the other. As much plaster should be used as will fill the case up about 1⁄2 an inch. ”

“ Lime plastering is composed of lime, sand, hair and water in proportions varying according to the nature of the work to be done. Internal Work.In all cases good materials, well mixed and skilfully applied, are essential to a perfect result. Plaster is applied in successive coats or layers on walls or lathing and gains its name from the number of these coats. “One coat” work is the coarsest and cheapest class of plastering, and is limited to inferior buildings, such as outhouses, where merely a rough coating is required to keep out the weather and draughts. ”

“ A broad thin strip of wood with a bevelled edge is very useful when stopping plaster walls, for in trying to stop a crack or hole with a sharp steel stopping knife, the surrounding face of the plaster may be badly scratched, which is only seen when the job is finished. ”

“ In this state, the plaster must be considered as perforated with little vacuities interspersed throughout its substance: and in consequence of this texture, when it afterward comes again into contact with water, or even with air loaded with humidity, these vacuities exert a capillary attraction, and imbibe the water afresh; and plaster of this sort can be used only in places that are dry, and sheltered from all accidental dampness. ”