CHAP. XII.
Of the taking of mezzotinto prints on glafs, and painting upon them with oil, or varnifh colours. '
T
HE painting on glafs, by means of mez-zotinto prints, is performed by cement-ing the printed fide of die prints to the furface of the glafs, by the afliftance of fome gIutin-\
ous body which will not diffolve in water ; and \ then destroying the texture of the paper by water, fo that it may be rubbed intirely off from \the cement upon the glafs; leaving, at the fame time, the whole of the ink of the print upon the cement, and glafs, in the fame manner a$ if die original impreffion had been made there;
by which method, a complete drawing of the pidture defigned is obtained on the glafs; and may be coloured by the ufe of oil, varnifh', or water colours.
The method of performing this is as follows. Procure a piece of the belt crown glafs as ' near as poflible in fize to the print to be taken ■
off; and varnifh it thinly over with turpentine, rendered a little more fluid by the addition of t oil of turpentine. Lay the print then on the \ glafs beginning at one end ; and prefling it gently down in every part in proceeding to the other: to prevent any veficles of air being formed, in tne laying it on, by the paper touching the cement unequally in different parts ; and to fettle the whole more clofely to the glafs, it is well to pafs over a wooden roller over it; which roller may be made of any kind of wood turned, and may be about two inches in diameter. Dry the glafs, with the print thus laid upon it, at the fire, till the turpentine be perfectly hard; and afterwards moiften the paper well with water, till it be thoroughly foaked. Then rub off the paper intirely from the cement, by gently rolling it under the finger ; and let it dry without any heat: the impreffion of the print will be found perfect on die glafs ; and ' may be painted over with either oil or varnifh colours.
The choice and treatment of the colours for painting in this way upon glafs, in either oil or varnifh, may be the fame as for any other method; and it is therefore needlefs to enumerate any further particulars, but to refer to the parts of this work where the nature and preparation of them, as well as the manner of compofirion of them, with the oils and varnifh, is before explained.