BUTTON, an article of dress, serving to fasten clothes tight about the body, made of metal, silk, mohair. &c. in val. rious forms. Metal buttons are either cast in moulds, in the manner of other small works, or made of thin plates of gold, silver, or brass, whose structure is very ingenious.
Of the manufacture of metal buttons.
These are originally formed in two differ ent ways ; the blanks are either pierced out of a large sheet of metal with a punch driven by a fly-press, or cast in a pair of flasks of moderate size, containing 10 or 12 dozen each. In this latter case, the shanks are previously fixed in 'the sand, exactly in the centre of the impression formed by each pattern, so as to have their extremities immersed in the melt ed metal when poured into the flask, by which means they are consequently firm ly fixed in the button when cooled. The former process is generally used for yel low buttons, and the latter for those of white metal. We shall first give an in stance of the former mode of procedure, as used in the manufacture of gilt but tons. The gilding metal is an alloy of copper and zinc, containing a smaller pro portion of the latter than ordinary brass, and is made either by fusing together the copper and zinc, or by fusing brass with the requisite additional proportion of cop per. This metal is first rolled into sheets of the intended thickness of the button, and the blanks are then pierced out as be fore mentioned. The blanks thus formed are, when intended for plain buttons, usu ally planished by a single stroke of a plain die driven by the same engine, the fly press; when for ornamental buttons, the fi gure is also frequently struck in like man ner by an appropriate die, though there are others which are ornamented by hand. The shanks, which are made with:wonder ful facility and expedition by means of a very curious engine, arc then temporarily attached to the bottom of each button by a wire clamp like a pair of sugar tongs, and a small quantity of solder and resin applied to each. They are in this state exposed to heat on an iron plate, contain ing about a gross, till the solder runs, and the shank becomes fixed to the but ton, after which they are put singly in a lathe, and their edges turned off smooth ly. The surface of the metal, which has become in a small degree oxydated by the action of the heat in soldering, is next to be cleaned, which in this, as in a great variety of other instances in the manufac ture of metallic articles, is effected by the process of dipping or pickling; that is, some dozens of them are put into an ear then vessel, pierced full of holes like a cullender; the whole dipped into a vessel of diluted nitric acid, suffered to drain for a few seconds, again dipped succes sively into four or five other vessels of pure water, and then dried.
The next operation is the rough burnish ing,which is performed by fixing the but tons in the lathe, and applying a burnish er of hard black stone from Derbyshire : the minute pores occasioned by the suc cessive action of the heat and the acid are thus closed, and the subsequent process of gilding considerably improved, both with regard to economy and perfection. The first step towards the gilding of all the alloys of copper consists in covering the surface uniformly with a thin stratum of mercury, by which mean's the amalgam, which is afterwards applied, attaches it self to it much more readily than it would otherwise do. This part of the process is called quicking,and is effected by stirring the buttons about with a brush, in a vessel containing a quantity of nitric acid super saturated w;t11 mercury, which latter is, of course, by the superior elective attrac ti onof the copper for the acid,precipitated in its metallic state on the bottoms, whose surfaces become uniformly and brilliantly covered with it. The mercury, which hangs in loose drops on the buttons, is then shaken off, by jerking the whole violently, in a kind of earthen cullender made for the purpose, and they are then ready for receiving the amalgam. The amalgam is made by heating a quantity of grain gold with mercury in an iron ladle; by which means the former is soon dis solved, and the whole is then poured into a vessel of cold water. The superabun dant mercury is strongly pressed out through a piece of chamois leather, and the remaining amalgam, which is of about the consistence of butter, is then fit for application. This is performed by stirring the buttons, whose surfaces are already thinly covered or wetted with mercury, in an earthen vessel, with the requisite proportion of amalgam and a small quan tity of diluted nitric acid, by which means the amalgam also attaches itself to their surfaces with a considerable degree of equality. The necessary quantity of gold is about five grains to a gross of buttons of an inch in diameter.