CHAP. III.
Of bronzing.
BRONZING is colouring, by metalline powders, plafter, or other bufts and fi- gures, in order to make them appear as if caft of copper or other metals.
This is ibmetimes done by means of cement; and fometimes without, in the inftance of pla-fter figures : but the bronzing is more durable and fecure when a cement is ufed.
The gold powders, and the aurum mofai-cum, we have before given the preparation of, are frequently employed for this purpofej but the proper bronzing ought to be of a deeperand redder colour, more refembling copper; which effect may be produced by grinding a very fmall quantity of red lead with thefe powders; or the proper powder of copper may be ufed : and may be prepared as follows.
“ Take filings of copper or flips of cop-
“ per plates j and diflblve them in any kind
“ of aqua fortis put into a glafs receiver, or
“ other proper formed veflel. ‘ When the
“ aqua fortis is faturated with the copper, take
out the flips of the plates j or, if filings were
“ ufed, pour off the folution from what rc-
“ mains undiflolved: and put into it fmall
“ bars of iron : which will precipitate the
*f copper from the aqua fortis in a powder of
“ the
** the proper appearance and 1 - r
ct powder ; and walh it clean from the
“ faits, by lèverai fucceffive quantities of frelh
** water.”
Where the appearance of brafs is defigned, the gold powders, or the aurum mofaicum, may be mixt with a little of the powder called argentum mufivum ; of which the prepara- tion is above given. Where no cement is ufed in bronzing, the powder mull be rubbed on the fubjedt intend- ed to be bronzed, by means of a piece of foft
leather, or fine linnen rag, till the whole liar-face be coloured.
The former method of ufing a cement in bronzing was, to mix the powders with llrong gum water, or ifinglafs fize ; and then with a brulh, or pencil, to lay diem on the fubjedl : but at prefentlbme ufe the japanner’s gold fize: and proceed in all relpedls in the fame manner as in gilding with the powders in other cales : for which ample diredlions have been before given.
This is the bell method hitherto pradtifed ; for the japanner*e gold fize binds the powders tq the ground, without the lead hazard of peeling or falling off ; which is liable to hap-pen when the gum water or glover’s or ifinglafs fizes are ufed : though, notwithllanding the au-thority of -the old pradtice for the contrary, even thefe cements will much tetter fecure them when they are laid on the ground, and the per. Pour off the water powders rubbed over them, than when both are mixed together, and die effect particularly of the aurum mofaicum will be much better in this way than the other.
The fidtitious filver powder, called theargen*' turn mufivum, may be ^jplied in the manner . of bronze, by thofe wnofe caprice difpofes them to filver figures or buds: but it is the only fort of filver powder, that fhould be ufed in this Way, for the reafon above given : and all fuch kind of filvering is much better omit» ted: as the whitenefs itfelf of plafter in figures or buffs, and much more a glofly or mining whitenefs, is injurious to their right effect j by its eluding the judgment of tne eye, withrefpedt to the proper form and proportion of the parts, from the falfe and pointed reflections or the lights, and the too faint force of the fhades: to remove which inconvenience it is probable was the flrff inducement to bronzing.