GLASS. 



good, and his tafte in ornaments and Mofaic far fuperior 

 to any of his predcceflbrs, and equal to the antique. 

 In 1 761, Mr. Paterfon, an audioneer late of Eflex-houfe 

 in London, exhibited the two firft auftions of painted glafs 

 imported from Flanders ; and undertook alfo to eftabhth a 

 manufacture of painted glafs : feveral of the pieces of this 

 ingenious artift exliibited colours vying in perfection with 

 the old paintings. 



Thofe beautiful works, among the painters in glafs, which 

 were made in the glafs-houfe, were of two kinds : in fome, 

 the colour was diffufed through the whole body of glafs ; 

 in others, whicli were the more common, the colour was 

 only on one fide, fcarce penetrating within the fubftance 

 above one-third of a line ; though this was, more or lefs, 

 according to the nature of the colour ; the yellow being al- 

 ways found to enter the deepeft. 



Thefe laft, though not fo ftrong and beautiful as the 

 former, were of more advantage to the workmen ; becaufe, 

 on the fame glafs, tliough already coloured, they could (hew 

 other kinds of colours, where there was occafion to embroider 

 draperies, enrich them with foliages, or reprefent other or- 

 naments of gold, filver, &c. 



In order to this, they made ufe of emery ; grinding, or 

 wearing down the furface of tlie glafs, till fuch time as 

 they were got through the colour, to the clear glafs : this 

 done, they applied the proper colours on the other fide 

 of the glafs. By this means the new colours were pre- 

 vented trom running and mixing among the former, when 

 the glafTes came to be expofed to the fire, as will hereafter 

 be (hewn. 



When the intended ornaments were to appear white, or 

 filvered, they contented themfelves to bare the glofs of its 

 colour with emery, without applying any new colour at all ; 

 and it was in this manner that they wrought the lights and 

 heightenings on all kinds of colours. 



The painting with vitreous colours on glafs depends en- 

 tirely o:; the fame principles as painting in enamel ; and 

 the manner of executing it is likewife the fame ; except 

 that in this the tranfparency of the colours being indif- 

 penfibly requifite, no fubftances can be ufed to form them 

 but fuch as vitrify perfectly : and, therefore, the great 

 objeft is to find a fet of colours, which are compofed of 

 fuch fubftances, as, by the admixture of other bodies, 

 may promote their vitrification and fufion ; are capable of 

 being converted into glafs ; and melting, in that Itate, 

 ■mth lefs heat than is fufficient to melt fuch other kinds 

 of glafs as may be chofen for the ground or body to be 

 painted ; to temper thefe colours, fo as to make them 

 proper to be worked with a pencil ; and to burn or reduce 

 them by heat, to a due ftate of fufion, without injuring 

 or melting the glafs which conftitutes the body painted. 

 The firft thing to be done, in order to paint on glafs, in 

 the modern way, is to delign, and even colour, the 

 whole fubjeft on paper. Then they make choice oi pieces 

 of glafs proper to receive the feveral parts, and proceed 

 to divide or diftribute the defign itfeif, or the paper it is 

 drawn on, into pieces fuitable to thofe of glals ; having 

 always a \\e\v that the glalfes may join in tlie contours 

 of the figures, and the folds of the draperies ; that the 

 carnations and other finer parts may not be damaged 

 by the lead wherewith the pieces are to be joined toge- 

 ther. 



The diftribution being made, they mark all the glafies, 

 as well as papers, with letters, or numbers, tliat they 

 may be known again ; which done, applying each part 

 of the defign on the glafs intended for it, they copy or 

 transfer the defign upon this glafs, with the black colour, 



Vol. XV r. 



diluted in gum-water ; by tracing and following all t!»» 

 lines and ftrokes, as they appear tlirough the ghifs, wiili 

 the point of a pencil. 



W hen thefe firft ftrokes are well dried, which happens 

 in about two days, the work being only in black and 

 white, they give it a flight wa(h over, with urine, gum 

 Arabic, and a little black ; and this feveral times repeat- 

 ed, according as the fliades are defired to be heightened ; 

 with this precaution, never to apply a new v*a(h, till the 

 former is fuiliciently dried. This done, the lights ar^ 

 riflngs are given, by rubbing off the colour in the refpec- 

 tive places, with a wooden point or t\x handle of the 

 pencil. 



As to the other colours above-mentioned, they are ufed 

 with gum-water, much as in painting in miniature ; taking 

 care to apply them lightly, for fear of effacing the out- 

 lines of the defign ; or even, for the greater fccurity, to 

 apply them on the other fide, efpecially yellow, which 

 is very pernicious to other colours, by blending there- 

 with. 



And here too, as in pieces of black and white, part'- 

 cular regard niuft be always had, not to lay colour on co- 

 lour, or lay on a new lay, till fuch time as the former are 

 well dried. It may be added, that the yellow is the oi.Iy 

 colour that penetrates through the glafs, and incorporates 

 therewith by the fire ; the reft, and particularly the blue, 

 which is very difficult to ufe, remaining on tlie furface, 

 or at leaft entering very little. Wlien the painting of all 

 the pieces is fi:uflied, they are carried to the furnace or 

 oven, to anneal or bake the colours. The furnace here 

 ufed is fmall, built of brick, from eighteen to thirty inches 

 fquare : at fix inches from the bottom is an aperture, to 

 put in the fuel, and maintain the fire. Over this aper- 

 ture is a grate, made of three fquare bars of iron, which 

 traverfe the furnace, and divide it into two parts. Two 

 inches above this partition is another little aperture, through 

 which they take out pieces, to examine how the coc^ion 

 goes forward. 



On the grate is placed a fquare earthen pan, fix or feven 

 inches deep ; and five or fix inciies lefs, ever)- way, than 

 the pefimeter of the furnace. On one fide hereof is a 

 little aperture, through which to make the trials, placed 

 directly oppofite to that of the furnaces deftined for the 

 fame end. 



In this pan are the pieces of glafs to be placed in the 

 following manner ; firft, the bottom of the pan is covered 

 with three ftrata, or layers of quicklime, pulverized ; 

 thofe ftrata being feparated by two others, of old broken 

 glafs : the defign whereof is to fccurc the painted glafs 

 from the too intenfe heat of the fire. This done, the glaffes 

 aie laid horizontally on the laft, or uppcrmoft, layer of 

 lime. 



The firft row of glafs, they cover over with a layer of 

 the fame powder an inch deep ; and over this they lay an- 

 other range of glaffes : and thus alternately, till the pan is 

 quite full ; taking care that the whole heap always ends 

 with a layer of the hme-powder. 



The pan thus prepared, they cover up the furnace witK 

 tiles, OH a fquare table of earthen-ware, clofely luted 

 all round ; only liaving five little apertures, one at each 

 corner, and another in the middle, to fervc as chim- 

 nies. 



Things thus difpofed, there remains nothing but to give 

 the lire to the work. The fire for the two firll hours mull 

 be very moderate ; and mult be increafed in proportion 

 as the' coction advances, for the fpace of ten or twelve 

 hours ; in which time it is ufuallv completed. At lall, 

 U u ■ the 



