S E C T I O N II.
Of the grounds for water colours.
T H E fubftance on which paintings with X water colours are ufually made, are crartoon, paper, (or a kind defigned for this p>urpofe), common paper, or vellum.
When paper of any proper kind is ufed, it is lufficient to prime it with ifinglafs, fize tlraickened properly with pearl white, and any pigment which will afford the colour the ground is defired to be : but common paper rrxay be rendered ftronger and fitter to receive tile colours, by laying on the back of it a °oat of ftarch boiled with water to a moderate ^Onfiftence, and rendered yet more tenacious the addition of a little ifinglafs. This ft'iould be laid very fmoothly with a brufh j **>d the paper, when near dry, muft be put "^twixt the leaves of a book, or betwixt two 'fleets of paper and two boards, and comprefif-ed by a weight laid on the books or boards; Two fheets of paper cemented together by the ftarch and iiingiafs, and treated in the fame manner, make a very commodious fiibftance for painting in miniature. It has been advifed to pounce paper deiigned for painting with water colours, or to rub them over with alum water: but as the intention of this is only to guard againft the defeat of paper that will not take ink or other aqueous fluids with? out running, it is much better to avoid the ufe of all.fuch paper; for the pounce prevents the colours working freely with the penal; and. the alum water changes feveral of the colours; as, for example, the litmus, and archal, if ufed, would be turned to a red from, blue or purple.
Vellum has been, likewife, directed to be pounced by fome of thofe, who have pretended to teach the belt methods of managing water colours: but, if it be good, it requires no other preparation than the flraining on a pafte-board, or other fuch proper body, and pruning it in the manner directed for paper: and if it fhould hap* pen to be greafy, the rubbing it over with the gall of any beaft will remedy the defeat, with*, out the inconvenience produced by the ufe of pounce. The flraining the vellum on die pafte-board, muft be effected by cementing them together with the ftarch prepared as above, or with iiingiafs fize, which is better for this pur-* pole: and the vellum muft be cut fo much bigger than the pafte-board, that it may lap over on every fide j in the doing which care muft be taken that it be equally ftretched on each fide, fb as to render the whole perfectly even.