SECT. VIII.

GLAZING.

2225. Glazing, or the business of the glazier, consists in fitting glass in sashes, frames, and casements, either in putty or lead. It may be classed under the heads of SASHWORK, LEADWORK, and FRETWORK. Glass, as a material, has been already described in Chap. II. Sect. XII. of this book.

2226. The tools necessary for SASHWORK are—a diamond, polished to a cutting point, and set in brass in an iron socket, to receive a wooden handle, by which it is held in a cutting direction. The top of the handle goes between the root of the forefinger and middle finger, and the under part between the point of the forefinger and thumb. In general, there is a notch on the side of the socket, which should be held next the lath. Some diamonds have more cuts than one. Plough diamonds have a square nut on the end of the socket next the glass, which, on running the nut square on the side of the lath, keeps it in the cutting direction. Glass benders have their plough diamonds without long handles, as they cannot make use of a lath in cutting, but direct them by the point of their middle finger. The ranging lath should be long enough to extend beyond the boundary of the table of glass. Ranging of glass is the cutting it in breadths, and is best done by one uninterrupted cut from one end to the other. A short lath is used for stripping the square to suit the rebate of the sash, as in ranging they are generally cut full. A square, for the more accurate cutting at the right angles from the range. The carpenter's chisel is used in paring away some of the rebate of the sash when the glass does not lie so flat as to allow a proper breadth for front putty. The glazing knife is used for laying in the putty on the rebates, for bedding in the glass, and finishing the front putty. A bradding hammer is made with a head in the form of a small parallelopiped, with a socket for the handle, using it at an obtuse angle from the middle of one of its sides. The square edges of the head drive the brads in a horizontal direction, and with this tool there is less liability to accident than with any other. Some use the basil of the chisel for the purpose. Brass points are con sidered the best for bradding; small cut brads are also used. All new works should be bradded, to prevent the glass being moved out of its bed. The duster is a large brush for brushing the putties, and taking the oil from the glass. The sash tool is used wet, for taking the oil from the inside after the back putties are cleared off. The hacking knife is for cleaning out the old putty from the rebates where squares are to be stopped in. The use of the glazier's rule needs no explanation: it is 2 feet long, doubling in four different pieces.

2226a. The putty in which the glazier beds the glass is of four sorts. Soft putty, which is composed of flour, whiting, and raw linseed oil; hard putty, composed of whiting and boiled linseed oil; harder pulty, the same ingredients as the last, with the addition of a small quantity of turpentine for more quickly drying it; hardest putty, composed of oil, red or white lead, and sand. The first of these putties is the most durable, because it forms an oleaginous coat on the surface, but it requires a long time for drying. The hard sorts are apt to crack if not soon well painted, and the hardest of them renders it difficult to replace a pane when broken; hence it is altogether unfit for hothouse and greenhouse work. Probably the best manner of fixing glass and glazed frames in stone mullions is with a mixture of Bath stone dust and linseed oil, made up similarly to putty. Its elasticity allows of any slight settlement if the work be new, and it is more of a waterproof cement than Portland, as it is not nearly so liable to crack: that cement, without a large proportion of sand, will almost invariably burst glass or stone after a few months; and it also stains freestones, Corsham Down stone especially, giving it the appearance of having been burnt. (Builder, 1864, p. 796.)

22266. To remove glass from old sashes, a mixture of 3 parts of American potash with 1 part of unslaked lime, laid on both sides with a stick, and allowed to remain for twentyfour hours, will soften the putty enough to cut out easily. This mixture will also take off paint, and even tar.

2226c. Many systems of glazing large roofs have been introduced of late years, each supposed to be an improvement upon the other, and recommended by the designers for billiard-rooms, picture-galleries, dining-rooms, concert-halls, yards, large span roofs, &c. Braby's patent glazing; glass set free, allowing expansion and contraction, and precluding breakage.

Brown's patent system of glass and iron roofing. No putty, zinc, galvanised iron, castiron, india-rubber, felt, asbestos, or other perishable material. Causley's system of glazing without putty, 1881.

Crowe's dry glazing; simple and cheap.

Drummond's patent roof-glazing; sash-bars in iron, steel, zinc, or wood.

Grover & Co.'s simplex glazing. No iron, zinc, or putty. Lead strips on wood-bars, &c. Helliwell's patent perfection system of imperishable glass roofing. No putty used. Jeffrey's patent system of glazing, guaranteed air and water tight.

Johnson Brothers & Co.'s patent imperishable glazing.

Mackenzie's patents, by the British Patent Glazing Company (Limited). No zinc used; a lead cushion over an iron bar.

Mellowes and Darby's eclipse glazing; tin-lead bar, V section.

Rendle's Acme glazing.

Rendle & Burrow's indestructible glazing. Wood sash-bar, the glass covered on it by a wood capping.

Shelley's patent standard system of glazing, using glass up to 10 feet in length, with his patent bars placed two feet apart.

The Pennycook patent universal system of glazing without putty.

Each system must be examined for its peculiarity.

2226d. The Transparent Wire Wove Roofing Company (Limited) has manufactured a substitute for glass, made in sheets 10 ft. by 4 ft., at 64d. per foot. Much is said in favour of it, and for many purposes it may work in usefully as a temporary material.

2226e. The diminution of light by passing through various sorts of glass has been given thus: British polished plate, 13 per cent.; rough cast plate, 30; rolled fluted plate, 4 flutes to the inch, 53; 32 oz. sheet, 22; common window glass, about 10; ground glass, from 30 to 60; opal globes, from 50 to 60; green, purple, and ruby glass, 82 to 89; and porcelain transparency, over 97. Light decreases in the ratio of the square of its distance from its sources.

2227. LEADWORK for fixed lights is used in ecclesiastical buildings, often in inferior offices, and frequently in country buildings. Frames made with crossbars receive these lights, which are fastened to saddle bars. Where openings are wanted, a casement is introduced of wood or iron. Sometimes a sliding frame is used, particularly for house windows. Plain, painted, and stained lead lights have of late years been largely introduced in the so-called "Queen Anne" designs, and adapted for blind or transom, fanlight, door panel, or window.

2228. The glazier's vice is for preparing the leaden slips called cames with grooves, &c., to fit them for the reception of glass. The German vices are the best, and turn out a variety of lead in different sizes. There are moulds belonging to these vices in which bars of lead are cast; in this form the mill receives them, and turns them out with two sides parallel to each other, and about of an inch broad, and a partition connecting the two sides together, about of an inch wide, forming on each side a groove nearby of an inch, and 6 feet long. The setting board is that on which the ridge of the light is worked, and divided into squares, and struck out with a chalk line, or drawn with a lath, which serve to guide the workman. One side and end is squared with a projecting bead or fillet. The latterkin is a piece of hard wood pointed, and so formed as to clear the groove of the lead, and widen it, for the more readily receiving the glass. The setting knife is a blade with a round end, loaded with lead at the bottom of the blade, and having a long square handle. The square end of the handle serves to force the squares home tight in the lead; being loaded with lead, it is of greater weight, and also cuts off the ends of the lead with greater ease, as in the course of working these lights the lead is always longer than is necessary till trimmed.

2229. The resin box contains powdered resin, which is put on all the joints previous to soldering. Clips are for holding the irons. All the intersections are soldered on both sides except the outside joints of the outer side, that is, where they come to the outer edge. These lights should be cemented, which is done by thin paint being run along the lead bars, and the chasm filled with dry whiting. After it has stood a short time, a small quantity of dry red or white lead is dusted over it, which will enable it to resist the weather well.

C

D

2229a. FRETWORK is the ornamental part of leadlight work, and consists in working ground or stained glass into different patterns and devices, as may be seen in the old stained glass windows. The leads used until the middle of the seventeenth century are nearly of one uniform width, and are much narrower in the leaf than the common modern leads. That this was the case, can be proved not only by the existence of the original leads themselves, but more satisfactorily perhaps by the black lines drawn upon the glass, with which the glass painters were accustomed sometimes to produce the effect of leads without unnecessarily cutting

B

3

ic Fig. 807d.

the glass. A in fig. 807d. represents an ancient lead of the usual width; B its section, consisting of the leaf, a and b, and the core c. C is the section of a German lead of the early part of the 14th century. D is a piece of modern fret lead of the ordinary width, and which is now considered (1847) as being very narrow; and E its section. The process of compressing the lead between rollers to the proper dimension makes them more rigid than the old leads. It is the practice at the present day to surround each glazing panel with a broad lead, that is, a lead three-quarters of an inch broad in the leaf, to strengthen the work (page 27.). Leads somewhat narrower than these were very extensively employed. An entire window. at Stowting Church, Kent, probably of the early part of the reign of Edward IV., was leaded with leads as F. The other lead, G, is of the early part of the reign of Henry VI., and is from Mells Church, Somersetshire, where similar lead is commonly used. This mode of strengthening the lead without increasing its width was not confined to the decorated period. Both these specimens had all the appearance of being cast in a mould. One of the faces in each is narrower than the others; these were placed outside, and the difference probably arose from decomposition of the metal. A still narrower lead may be occasionally met with in heraldry and other minute mosaic work of the 15th and 16th centuries. It is hardly necessary to observe that the greater the number of leads employed, the weaker individually may they be made (page 259-61.). The width of the leads must be proportionate to that of the lines usually painted on the glass, for the leaden outlines will easily be detected if they are much stronger than the painted ones. The effect of the increased width of modern leads, E, although so trifling, is very perceptible.

22296. Saddle bars in ancient windows will be found to be usually placed from 8 to 9 inches apart, which seems to be the most agreeable distance, though one of 6 inches does not appear too little in some cases. The great object is to avoid, as much as possible, causing the light to appear as if it were divided into a number of square compartments, by making the height too nearly the width of the glass. Amongst the advantages resulting from the use of saddle bars at short intervals, is the opportunity it affords the glazier of carrying a horizontal lead across the light immediately in front of each saddle bar, the opacity of which hides the lead. This method of concealing lead work was carried to such perfection during the first half of the 16th century, that a person ignorant of it would find it difficult to conceive how some of the works of that period were constructed. 2229c. Iron standards or stancheons, in ancient windows put through the saddle bars, should be retained in pattern windows, which they improve, and do not appear to be out of place in picture windows whenever they do not happen to pass immediately behind the head of the principal figure. They seem also on the whole to improve the effect of the architecture from without. (WINSTON, Inquiry into Style in Glass Painting, Svo. 1847.)

2229d. It is stated that at Cologne Cathedral the glass is strong; the different pieces are joined together with lead, and soldered with tin, both inside and outside, which gives the whole great strength. The panes are fastened upon iron frames, which are again fastened upon rods. In the interior the panes are screwed upon iron bars, half an inch thick, which are let into the masonry.

2230. In London a large portion of the glazier's business consists in cleaning windows, 2231. Glazed partitions formed of wood, or of iron frames with the lower panels filled in with slate, are now very usual in warehouses, banks. and counting-houses. If sound be desired not to pass through such fittings, they must be glazed with extra thick glass; but double sheets or squares, placed about half an inch or more apart, and carefully puttied, is best. This method will also conduce to the warmth of the room. Double windows to the fronts of houses are common fittings to effect both the above purposes.

2231a. Glass has been introduced for a variety of building purposes. Thus, Lloyd and Summerfield's patent crystal window bars, for windows, shop fronts, and cases, are not uncommon. They are fitted with arched heads and spandrils of glass, having patterns, silvered or gilt, on a coloured ground. Glass tiles and slates are a useful auxiliary to a roof where a small modicum of light is required. Lockhead's perforated glass ventilator can either be set in the sash, or fixed outside of it in a frame for the whole width of the opening, air being admitted by moving the sash. For the like purpose are such inventions as Moore's louvre ventilators in a sash pane; Boyle's draughtless window ventilators, being a fine gauze of wire set in a pane of glass, and used with or without a glass cover; and the circular glass "revolving" ventilator. Glass balusters and handrails; pilasters for chimneypieces; door handles, knobs, and plates; mirror frames; trays for dairies; cut crystal and opal letters; Pratt's patent process of gilding by precipitation (1886), are among other useful inventions in this material. See Pavement Lights, par 22951.

2231b. Coloured or stained glass. We can only here name the varieties. There are three modes of colouring glass: I. Pot metal glass, in which the colour is mixed up with the melten mass. II Flashed, covered, or coated gla s, formed by uniting a thin layer of coloured glass with another layer, either of a different col. ur or colourless. III. Painted glass, the white substance being painted on, and then the colour or pigment burut in. The colouring materials are in all cases metallic substances. Such are the methods by which all coloured glass windows are produced.

2231c. For ornamental purposes, besides coloured glass, glass may have a ground surface, which is obtained by grinding it with a stone, or by the use of fluoric acid. Embossed glass, which permits the application of devices, according to the fancy of the designer or intention of the manufacturer, is effected by covering the square of glass with a varnish, except where the device is intended. An acid is then poured on which eats away the uncovered glass for a small depth. The varnish is then cleaned off, and the general surface is ground as usual. Its imitation is obtained by covering the plate with a varnish, a lace or stencil pattern placed on it, then dusted over with a colouring matter in the state of fine powder, and the plate thus treated sufficiently heated to vitrify and fix the dusted varnish to the glass. Messrs. Chance, and other manufacturers, sell various enamelled stencilled patterns, as white enamell d, enamelled and flocked, embossed repeated pattern, stained enamelled, and double etched glass, self shadowed glass, patent polychromatic glass, printed glass, stamped in colours, and many other kinds, all which are better seen at the factories than described. 2231d. The compressive strength of glass, that is, its resistance to a force tending to crush it, is about 12 tons per square inch: This is nearly equal to one quarter the stre. gth of cast iron. Glass has three times the specific gravity of iron. In the form of bars, a favourable shape for developing a highly tensile strength, one ton per square inch of area is the highest amount to be assumed for it.

2231e. MOSAIC WORK. This durable manner of decoration in glass, requires a short notice. The Roman mosaic is composed of pieces of enamelled glass, thus rendered opaque, sometimes called smalto and sometimes paste, made of all kinds of colours and of every different hue For large pictures they take the form of small cakes. For small works they are produced as threads, varying in thickness from that of a piece of string to the finest cotton thread. The Venetian mosaic pictures are formed of pieces of very irregular shapes and sizes, of all colours and tones of colours; the ground tint almost invariably prevailing is gold. The manner of execution is always large and coarse, and rarely approaches any neatness of joint or regularity of bedding. Opus Grecanicum consists in the insertion, into grooves cut in white marble to a depth of about half an inch, of small cubes of these coloured and gilded smalto, and in the arrangement of these forms in such geomeʼricul combination as to compose the most elaborate patterns. It was customary to combine the bands of this mosaic work with large slabs of Serpentine, Porphyry, Pavonazzetto, and other valuable marbles. and to use it in the decoration of ambones, cancelli, &c.; its use externally was comparatively rare. The hexagon, triangle, square, and octagon, form the usual bases of most of the specimens of this ingenious art to be found in Italy. Patterns of accumulating intricacy are seen at Palermo, and at Monreale. Illustrations in colour are given in the useful work on Mosaics, by M. D. Wyatt.

2231f. Coloured enamels are made of a vitreous paste (or glass), to this are added other mineral substances, which, when properly prepared and fused together, im; art to the paste its density and extreme hardness. and also its colour; the better the manufacture, the more satisfactory the appearance and the greater the durability of the mosaic work. In an imperfect manufacture, the mosaic is liable to be injured by damp, smoke, and all atmospheric changes; when well produced, they can be made to give precisely the same effect as the painting.

2231g. Goll and silver enamels were introduced: these are made of the precious metals, but in such thin sheets that their use is comparatively inexpensive. The process is a difficult one, for, to produce true gold and silver enamels, great knowledge and experience are necessary. On a ground of thick glass or enamel, according as it is desired to render the gold enamel transparent or opaque, or to impart to it a warm or variegated colour, there is laid a leaf of gold or silver, which is attached principally by the action of fire; then a film of the purest glass is spread over it, and this may either be perfectly colourless or of any tint that may be required. When well manufactured, these thin layers, after being fused, become perfectly united with each other, and form a homogeneous body, and the metal is for ever protected against all possibility of injury from any cause except actual violence.

66

2231h. Stevens has produced a new kind of glass mosaic, executed at about one third the price of the ancient manufacture of this kind. The glass is stained or gilt, and the method is adapted for many purposes. Messrs. Rust are working in gold, silver, and enamel mosaics of their own invention; and Dr. Salviati employs his indestructible system of Venetian enamel-mosaic, in works, in a comparatively inexpensive and expeditious manner." At the Wolsey tomb-house, at Windsor, the entire ceiling, consisting of 2,100 feet, was decorated in the space of ten months, including the time of the transit of the mosaics from Venice; and was executed, with the scaffolding, at the price of 4,725. It was also employed at St. Paul's Cathedral, for the figure of the prophet Isaiah, covering 250 feet, which was executed and fixed in two months, at the price of 600l. (Lecture read at Leeds, by A. Salviati, 1865.)

2231i. The cements used are of three sorts. The first, for large tessera in forming Boors, is composed of pitch, mixed with a black earth. The second, for stones of a mid

dling dimension, is made of tufa and oil. The third, for the more delicate mosaics of pieces of glass, is made of white of lime, pounded bricks, gum andragan, and the white of eggs. The ancients are said to have used 1 part of slaked lime and 3 parts of pounded marble, made up with water and white of egg. But as this is considered to harden too quickly, a mixture of 1 part of slaked lime, and 3 parts of powdered travertine stone, mixed up with linseed oil, and kept stirred every day, is used, adding oil as it dries. The mass is ready sooner in warm weather than in cold, varying from 20 to 30 days, when it is like a smooth ointment. For the larger works, Keene's, Portland, or other similar cements might be used.

SECT. IX.
PLASTERING.

2232. In the finishing of our dwellings, the decoration owes much of its effect to the labours of the plasterer: it is in his department to lay the ceilings, and to give, by means of plaster, a smooth coat to the walls, so as to hide the irregularities left by the bricklayer and mason, and make them sightly and agreeable. He also, in the better sort of buildings, furnishes plain and decorated mouldings for the cornices and ceilings; and in the external parts, where stone is expensive or not to be procured, covers the exterior walls with stucco or other composition imitative of stone.

2233. The plasterer's tools are-a spade or shovel of the usual description; a rake with two or three prongs bent downwards from the line of the handle, for mixing the hair and mortar together; stopping and picking out tools; rules called straight edges; wood models; and trowels of two sorts and various sizes, namely, the laying and smoothing tools, consisting of flat pieces of hardened iron, about 10 inches long, and 24 inches wide, very thin, and ground to a semicircular shape at one end, but square at the other. Near the square end on the back of the plate a small iron rod is rivetted, with two legs, whereof one is fixed to the plate, and a round wooden handle is adapted to the other. All the first coats of plastering are laid on with this tool, as is also the last, or setting, as it is technically called. The other sorts of trowels are of three or more sizes, and are used for gauging the fine stuff and plaster for cornices, mouldings, &c. The length of these trowels is, the largest about 7 inches in length on the plate, and the smallest 2 or 3 inches: they are of polished steel, converging gradually to a point, with handles of mahogany adapted to the heel or broad end with a deep brass ferrule.

2234. The stopping and picking out tools are of polished steel, of various sizes, about 7 or 8 inches long and half an inch broad, flattened at both ends, and somewhat rounded. They are used for modelling and finishing mitres and returns to cornices, as also for filling up and finishing ornaments at their joinings. There is also used a small instrument, which is a piece of thin fir 6 or 7 inches square, called a hawk, with a handle vertical to it, for holding small quantities of plaster.

2235. The composition used by the plasterer is a groundwork of lime and hair, on which, for the finish, a coating of finer material is laid. The sorts of it are various; as, for instance, white lime and hair mortar on bare walls; the same on laths as for partitions and plain ceilings; for renewing the insides of walls; roughcasting on laths; plastering on brickwork with finishing mortar, in imitation of stone work, and the like upon laths. For cornices and the decorations of mouldings, the material is plaster of Paris, one which facilitates the giving by casts the required form and finish to the superior parts of his work. The plasterer uses it also for mixing with lime and hair, where the work is required to dry and set hard in a short time. For inside work, the lime and hair, or coarse stuff, is prepared, like common mortar, with sand; but in the mixing, hair of the bullock, obtained from the tanners' yards, is added to it, and worked in with the rake, so as to distribute it over the mass as equally as possible.

2236. What is called fine stuff is made of pure lime, slaked with a small quantity of water, and afterwards, without the addition of any other material, saturated with water, and in a semi-fluid state placed in a tub to remain until the water has evaporated. In some cases, for better binding the work, a small quantity of hair is worked into the composition. For interior work, the fine stuff is mixed with one part of very fine washed sand to three parts of fine stuff, and is then used for trowelled or bastard stucco, which makes a proper surface for receiving painting.

About

2237. What is called gauge stuff is composed of fine stuff and plaster of Paris, in proportions according to the rapidity with which the work is wanted to be finished. four-fifths of fine stuff to one of the last is sufficient, if time can be allowed for the setting. This composition is chiefly used for cornices and mouldings, run with a wooden mould. We may here mention that it is of the utmost importance, in plasterers' work, that the lime should be most thoroughly slaked, or the consequence will be blisters thrown out upon the work after it is finished. Many plasterers keep their stuffs a considerable