246 



GLASS 



these soluble silicates, asserts, in an essay written 

 in 1876, that if, instead of silicate of soda or silicate 

 of potash, a solution of aluminate and silicate of 

 potash be used with the fresco colours on a properly 

 prepared ground there is no fear of the surface de- 

 caying, and adds that paintings executed in this 

 way have stood for many years. The plaster- 

 ground should consist of sand and lime, but no 

 plaster of Paris should be mixed with it. 



The name Volcanic Glass is not infrequently 

 given to Obsidian (q.v. ), as also to vitreous lava, 

 and even to a kind of pitchstone. 



See Neri, Ars Vitraria ( Amsterdam, 1668 ) ; Pellat, 

 .Curiosities of Glass-making (1849); Sauzay, Marvels of 

 Glass-making ( 1869 ) ; Peligot, Le Verre, son Histoire, sa 

 Fabrication ( 1877 ) ; Nesbit, Glass : South Kensington 

 Museum Art Handbook (1878); Froehner, La Vewerie 

 Antique (1879); Gerner, Die Glas Fabrikation (1880) ; 

 Chance, Treatise on Crown and Sheet Glass ( 1883 ) ; M. 

 A. Wallace-Dunlop, Glass in the Old World (1883); 

 Gerspach, L'Art de la Verrerie (1885). 



Glass, PAINTED or STAINED. There are two 

 kinds of painted glass known in modern times, 

 Enamel and Mosaic glass. In enamel glass proper 

 certain fusible pigments are painted on a sheet of 

 white glass, which is then fired, and the result is a 

 picture the tints of which even in the high lights 

 are not wholly transparent. A modification of 

 this method produces its picture partly by enamel- 

 ling on white glass, partly by the use of pot-metal 

 glass (i.e. glass coloured while in a state of fusion, 

 and therefore of the same tint all through), the 

 colour of which is heightened or modified by the 

 use of enamels. In this style, if any junction 

 between two pieces of glass becomes necessary, the 

 lead calms used for the purpose are studiously con- 

 cealed by being made to run along leading lines of 

 drapery or other forms in the picture. The object 

 of this enamel and semi-enamel glass-painting is 

 the closest possible imitation of an oil or water- 

 colour picture ; and the results of it are never satis- 

 factory. For at the best it can only do with diffi- 

 culty and imperfectly what the oil-painting does 

 with ease and perfection ; while at the same time 

 it refuses to avail itself of the special characteristics 

 of glass, which can produce effects that no opaque 

 painting can approach. This imitation of easel or 

 wall pictures also leads the designer into making 

 designs unfitted for the ornament of windows, and 

 wandering from their true purpose of decoration. 

 Indeed, not infrequently the work of a great 

 master in picture-painting is taken as a model for 

 a stained-glass window, and laboriously and servilely 

 imitated, with the result that a mere caricature of 

 the great work is produced, which is as far as 

 possible from being an ' ornament ' to the building 

 in which it is placed. 



The only method capable of producing stained 

 glass which shall be beautiful and interesting, and 

 which at the same time can plead some reason for 

 its existence, is that which has been called mosaic 

 glass, the process of which very briefly stated is as 

 follows : 



A design is made wherein the drawing is given 

 and the colours indicated, which is the working- 

 drawing of the glass-painter. From this working- 

 drawing a kind of map is made which gives all the 

 various pieces of the mosaic. The glazier cuts these 

 pieces out from sheets of glass of various colours, 

 and hands them back to the painter, who proceeds 

 first to paint the leading lines with a solid opaque 

 enamel, the colouring matter of which is an oxide 

 of iron. This being done ( and the glass sometimes 

 having been fired at once, but sometimes not), the 

 pieces of glass are stuck together temporarily (by 

 means of wax) on a glass easel, and the painter 

 slightly shades his bold traced lines with the same 

 opaque colour ; using sometimes washes ( in which 



case, of course, the colour is much diluted, and is 

 only semi-opaque), and sometimes hatching of 

 lightly laid-on lines, as in a black and white draw- 

 ing on paper. Sometimes both washes and hatch- 

 ing are used, and sometimes the washed shadows 

 are ' stippled ' i.e. part of the colour is removed by 

 dabbing it with the end of a broad brush. In any 

 case the object of the methods of shading is to keep 

 the shadows as clear, and to dull the glass as little 

 as the explanation or expression of the subject will 

 admit of. Two or three or more firings are necessary 

 during the process of this painting, but as far as the 

 painting as distinguished from the mosaic is con- 

 cerned this is all that has to be done, though it 

 must be said that to do it well requires considerable 

 experience and artistic skill and feeling. 



This painting being done, the glass goes back to 

 the glazier's bench again, and he ' leads it up ' (Le. 

 joins it together with lead calms soldered at the 

 junction), and the window, after having been solid- 

 ified by a stiff cement or putty rubbed into the 

 leaf of the leads, has then only to be put in its 

 place and strengthened by the due iron stay-bars. 

 It may be mentioned here that in this mosaic glass- 

 painting, so far from there being any necessity for 

 concealing the 'leads,' it is highly desirable to 

 break up the surface of the work by means of them, 

 always taking care that their direction is carefully 

 considered from the point of view of their appear- 

 ance. The obvious strength which the network of 

 leads gives to the window on the one hand, and 

 the obvious necessity for picking out small pieces 

 of exquisite colour on the other, take away all 

 sense of discomfort in the arbitrary disposition of 

 these constructive lines. 



A mosaic stained -glass window, therefore, seems 

 a very simple affair, and so it is as a process 

 (bating some difficulties in the making of the 

 material). Its real difficulties are all on tlie artistic 

 side, and have to do with the qualities of design 

 and the choice of material. 



As to the design, it must be repeated that sugges- 

 tion, not imitation, of form is the thing to be aimed 

 at. Again, the shading is, as above said, for the 

 sake of explanation, not to make the work look 

 round, and also for diversifying the surface of 

 the glass, to make it look rich in colour and 

 full of detail. The qualities needed in the de- 

 sign, therefore, are beauty and character of outline ; 

 exquisite, clear, precise drawing of incident, such 

 especially as the folds of drapery. The whole 

 design should be full of clear, crisp, easily-read 

 incident. Vagueness and blur are more out of 

 place here than in any other form of art ; and 

 academical emptiness is as great a fault as these. 

 Whatever key of colour may be chosen, the colour 

 should always be clear, bright, and emphatic. . Any 

 artist who has no liking for bright colour had better 

 hold his hand from stained-glass designing. 



Consideration of the colour of the work naturally 

 leads to consideration of the material. The ordinary 

 machine-made window-glass, thin, and without any 

 variety of surface, is wholly unfit for stained glass, 

 but it should be stated in passing that a modern 

 mechanical imitation of the unevenness of surface 

 found in old glass, which is commonly called ' cathe- 

 dVal glass,' is the worst of all materials for windows, 

 and should never be used in any kind of glazing, 

 ornamental or plain. The due varieties of surface 

 are those that occur naturally in the process of 

 making thick cylinder or crown glass. All glass 

 used for glass-painting should be very thick, or, 

 whatever the pigments used for colouring may be, 

 the effect will be poor, starved, and, if bright 

 colours be used, glaring. The glass which has to 

 show as white should, when laid on a sheet of 

 white paper, be of a yellowish-green colour ; for 

 the colours in stained glass are so powerful that 



