OP JAPANNING';
4*3
SECTION IV.
Of varnijhing japan work.
THE laft, and finilhing part of japanning, lies in die laying on and polifhing the outer coats of varnilh ; which are neceflary, as well ia the pieces that have only one limple
ground of colour j as with thofe that are paint- ed. This is in general belt done with com-mon feed-lac varnilh; except in the inftances* and on thole occahons, where I have already Ihewn other methods to be more expedient: and the fame realons, which decide as to the fitnels or impropriety of the varnilhes, with refpeCt to the colours of the ground, hold e-qually well with regard to thole of the paint- ing. For where brightnefs is the moll mate- rial point, and a tinge of yellow will injure it, feed-lac mult give way to the whiter gums : but where hardnefs, and a greater tenacity, are molt eflential, it mull be adhered to: and where both are fo neceffary, that it is proper one Ihould give way to the other, in a certain degree reciprocally, a mixt varnilli mull be adopted.
This mixt varnilh, as I before obferved, ihould be made of the pickt feed-lac, as directed in p. 414. The common feed-lac varnilh, which is the moll ufeful preparation of the kind hitherto invented, may be thus made.
“ Take of feed-lac three ounces, and put “ into water to free it from the flicks and filth that frequently are intermixed with it j “ and which muft be done by ftirring it about “ and then pouring off the water, and adding “ fre(h quanties in order to repeat the opera- <c tion, till it be freed from all impurities; as <c it very effectually may be by this means.
Dry it then, and powder it grofsly; and “ put it, with a pint of rectified fpirit of wine, into a bottle, of which it will not fill above “ two thirds. Shake the mixture well to “ gether; and place the bottle in a gentle ** heat, till the feed appear to be diffolved; the ftiaking being in the mean time repeated as often as may be convenient: and then “ pour off all which can be obtained clear ** by that method : and ftrain the remainder “ through a coarfe cloth. The varnifh thus u prepared muft be kept for ufe in a bottle “ well ftopt.”
When the ipirit of wine is very ftrong, it will difiblve a greater proportion of the feed- lac : but this will faturate the common, which is feldom of a ftrength fufficient for making varnifhes in perfection. As the chilling, which i6 the moft inconvenient accident attending thofe of this kind, is prevented, or produced more frequently, according to die ftrength of the fpirit, I will take this opportunity of (hewing a method by which, weaker rectified fpirits paay with great eafe, at any time, be freed from the phlegm, and rendered of the firfl degree of flrength. .
“ Take a pint of the common rectified c* fpirit of wine; and put it into a bottle, of “ which it will not fill above three parts. “ Add to it half an ounce of pearl-afhes, fait “ of tartar, or any other alkaline fait, heated ** red hot, and powdered, as well as it can be lf without much lofs of its heat. Shake the ** mixture frequently for the fpace of half an '<f hour; before which time, a great part of “ the phlegm will be feparated from the <( fpirit; and will appear, together with the c< undiflolved part of the falts, in the bottom “ of the bottle. Let the fpirit then be pour- “ ed off, or freed from the phlegm and falts “ by means of a tritorium or feparating furv- <f nel; and let half an ounce of the pearl-afhes, “ heated and powdered as before, be added u to it, and the fame treatment repeated. ** This may be done a third time, if the “ quantity of phlegm feparated by the addi- “ tion of the pearl-afhes appear confiderable. “ An ounce cf alum reduced to powder and “ made hot, but not burnt, muft then be put “ into the fpirit; and fuffered to remain fome il hours; the bottle being frequently fhaken. “ After which, the fpirit, being poured off <l from it, will be fit for ufe.”
The addition of the alum is neceflary, to • neutralize the remains of the alkaline fait OF pearl-afhes; which would otherwife greatly deprave the fpirit with refpedt to vaj-nifhes and laquers, where vegetable colours are concerned ; and mull confequently render another di- ihllation necefiary.
The manner of ufing the feed-lac, or white varnifhes, isthe fame; except with regard to the fubfiance-ufed in polifhing; which, where a. pure white, or great cleamefs erf* other colours, is in queftion, fhould be itfelf white: whereas the browner forts of polifhing duft, as being- cheaper, and doing their bufinefs with great«: djfpatch, may be ufed in other cafes. The pieces of work to be vamifhed fhould. be placed near a fire, or in a room where there is a ftove; and made perfedly dry: and then the varnifh may be rubbed over them by the proper brufhes made for that purpofe, beginning in the middle, and paffing the brufh to one end; and then, with another firoke from the middle, paffing it to the other. But no part fhould be eroded or twice pafied over, in forming one coat, where it can poffibly be avoided. When one coat is dry, another muff be laid over it; and this ttiuft be continued at lead: five or fix times, or more; if, on trial, there be not a diffident, thicknefs of varnifh to bear the polifh, without laying bare the painting, or the ground colour underneath.
When a fufficient number of coats is thus laid on, the work is fit to be polifhed: which muff be done, in common cafes, by rubbing it with a rag dipped in tripoli or pumice ftonc (commonly called rotten Jtone finely powder.ed: but towards the end of the rubbing, a little oil of any kind fhould be ufed along with the powder * and when the work appears fuf- ficiently bright and glofiy, it fhould be well rubbed with the oil alone, to clean it from die powder; and give it a ftill brighter luftre.
. In the cafe of white grounds, inftead of the tripoli or pumice itone, fine putty or whiting mufl be ufed; both which fhould be wafhed over to prevent the danger of damaging the work from any fend or other gritty matter, that may happen to be commixt with them*
. It is a great improvement of all funds of japan work, to harden die varnifh by means of heat5 which, in every degree that it can be applied fhort of what would burn or calcine the matter, tends to give it a more firm and ftrong texture. Where metals form the body, therefore, a very hot ftove may be ufed, and the pieces of work may be continued in it a confiderable time; especially if the heat be gradually increafed: but where wood is in queltion, heat mull be fparingly ufed} as it would otherwife warp or fhrink the body, fb ft? to injure die general figure. -