« AnteriorContinuar »
The small refuse powder which has between the lamp and the block, causes passed through the sieve, is again placed the light to fall directly upon the block. in the granulator, and acted upon as be
FIG. 30.fore described.
Glazing.-The powder is placed in a cask, or barrel, which revolves on its axis at about 40 revolutions a minute; by the friction of the grains against each other they become round, smooth, and polished, in which state the powder will bear the shaking and friction of carriage without injury, and is less likely to absorb moisture than when in rough and angular grains.
Drying.-The powder must not be too rapidly dried, a temperature commencing at about 66° F., and gradually increased to 130° or 140° F., is a safe one; the operation requires from 3 to 4 hours, and is best performed in a room warmed by steam pipes or hot-air flues. The powder is then fit for use,
The dotted line shows the direction of
the light; by Towering the lamp this and may be packed in sacks, to be after
light would take a more horizontal diwards placed in casks, or in double
rection, thus enabling the engraver to casks ; sporting powder is usually packed
work farther from the lamp. A shade in tin canisters.
over the eyes is occasionally used as a Pharaoh's Serpents.-Fuse in a
protection from the light of the lamp. crucible equal parts by weight of yellow
TOOLS.—These consist of gravers, tintprussiate of potash and flower of sulphur, frequently it is advisable, if the
| tools, gouges or scoopers, flat tools or
| chisels, and a sharp-edged scraper, someheat cannot be well regulated, to include
| thing like a copper-plate engraver's bura little carbonate of potash; lixiviate
nisher, which is used for lowering the the mass with water and filter; the fil
| block. Of each of these tools several trate will be sulphocyanide of potas
sizes are required. sium, which, upon being added to a solution of mercury dissolved in nitric acid,
| Gravers. The outline tool, Fig. 31, is
| chiefly used for separating one figure gives a copious precipitate of sulphocyanide of mercury; collect this; wash
FIG. 31 well with water, and dry; roll into a small pyramid, cover with tin-foil, and when dry it is ready to be lit.
2 Engraving on Wood. — Engraver's Lamp. — A clear and steady from another, and for outlines. A is light, directed immediately upon the the back of the tool; B, the face ; C, the block to be cut, is a most important point; D is technically termed the belly. point, and in working by lamplight it is The horizontal line, 2, shows the surface necessary to protect the eyes from its of the block. All the handles when heat and glare. The lamp shown in received from the turner's are circular, Fig. 30 can be raised or lowered at plea- but as soon as the tool has been inserted sure by sliding the bracket up or down a segment is cut away from the lower the standard, it being fixed in the de- part, so that the tool may clear the block. sired position by means of the small set The blade should be very fine at the screw. A large globe of transparent point, so that the line it cuts may not glass, filled with clean water, placed I be visible when the block 's printed, its
chief duty being to form a termination point a very slight inclination of the to a number of lines running in another hand will cause a perceptible irregudirection. Although the point should be fine, the blade must not be too thin, for
Fig. 33. It would then only make a small open T777--7PET: 4: ing, which would probably close up when the block was put in the press. When the tool becomes too thin at the point, the lower part must be rubbed on a hone to enable it to cut out the wood instead of sinking into it. Nine gravers of different sizes, starting from
larity in the distance of the lines, be
larity in the distance of the the outline tool, are sufficient for ordi sides tending to undercut the line left, nary work. The blades as made are which must be carefully avoided. Fig. very similar to those used in copper- 34 shows the points and faces of the plate engraving; the necessary shape for
Fig. 34. wood engraving is obtained by rubbing the points on a Turkey stone. The faces, and part of the backs, of nine gravers of
-Bdifferent sizes, are shown on Fig. 32;
two tools, from a comparison of which this statement will be readily understood. As the width of the tint-tool at
B is little more than at A, it causes only the dotted line, A C, shows the extent a very slight difference in the distance to which the tool is sometimes ground of the lines cut, if inclined to the right down to broaden the point. This grind- or the left, as compared with the use of ing rounds the point of the tool, instead | the graver. Tint-tools that are strong of leaving it straight, as shown at A B. in the back are to be preferred as less Except for the parallel lines, called likely to bend, and giving greater freetints, these gravers are used for nearly dom of execution than weak ones. A tintall kinds of work. The width of the tool that is thicker at the back than line cut out is regulated by the thick at the lower part, leaves the black raised ness of the graver near the point, and lines solid at their base, as in Fig. 35, the pressure of the engraver's hand.
FIG. 36. Tint-tools.—The parallel lines forming an even and uniform tint, as in the representation of a clear sky, are obtained by what is called the tint-tool, which is thinner at the back, but deeper the block being less liable to damage at the side, than the graver, and the than in the case of Fig. 36, in which the angle of the face at the point is much lines are no thicker at their base than more acute, as shown on Fig. 33: A is at the surface. The face of both gravers a side view of the blade; B shows the and tint-tools should be kept rather long faces of nine tint-tools of varying fine- than short; though if the point be ness. The handle is of the same form as ground too fine it will be very liable to that used for the graver. The graver break. When, as in Fig. 37, the face is should not be used in place of the tint- long,—or, strictly speaking, when the tool, as from the greater width of its angle formed by the plane of the face
and the lower line of the blade is com- | oil, or allowed to cool gradually. If paratively acute,-a line is cut with removed from the iron while it is still
of a straw colour, it will have been FIG. 37.
softened no more than sufficient; but should it have acquired a purple tinge, it will have been softened too much, and instead of breaking at the point, as be
fore, it will bend. A small grindstone much greater clearness than when the is of great service in grinding down the . face is comparatively obtuse, and the faces of tools that have become obtuse. small shaving cut out turns gently over A Turkey stone is a very good substitute, towards the hand. When, however, the as, besides reducing the face, the tool face of the tool approaches to the shape receives a point at the same time; but seen in Fig. 38, the reverse happens; the this requires more time. Some engravers
use only a Turkey stone for sharpening Fig. 38.
their tools; a hone in addition is of great service. A graver that has received a final polish on a hone cuts a clearer line
than one which has only been sharpened small shaving is rather ploughed out | on a Turkey stone; it also cuts more than cleanly cut out; and the force pleasantly, gliding smoothly through the necessary to push the tool forward wood, if it be of good quality, without frequently causes small pieces to fly stirring a particle on either side of the out at each side of the hollowed line, line. The gravers and tint-tools used more especially if the wood is dry. The for engraving on a plane surface are shaving, also, instead of turning aside over | straight at the point, as are here reprethe face of the tool, turns over before the sented, Figs. 40 and 41; but for engravpoint, as in Fig. 38, and hinders the engraver from seeing that part of the pen
Fig. 40. cilled line which is directly under it. A short-faced tool of itself prevents the engraver from distinctly seeing the point.
FIG. 41. When the face of a tool has become obtuse it ought to be ground to a proper form ; for instance, from the shape of the figure A to that of B, Fig. 39. ing on a block rendered concave in cer
tain parts by lowering, it is necessary FIG. 39.
that the point should incline slightly upwards, as in Fig. 40. The dotted line shows the direction of the point used for plane surface engraving. There is no difficulty in getting a tool to descend on one side of a part hollowed out or lowered; but unless the point is slightly inclined upwards, as is here shown, it is
extremely difficult to make it ascend on Preparing Gravers and Tint-tools. the side opposite without getting too Gravers and tint-tools, when first re much hold, and thus producing a wider ceived from the makers, are generally white line than intended. too hard—a defect that is soon discovered Gouges and Chisels, A to E, Fig. 42.by the point breaking off short as soon as Gouges of different sizes are used for it enters the wood. To remedy this, the scooping out the wood towards the centre blade of the tool must be tempered to a of the block; whilst flat tools, or chisels, straw colour, and either dipped in sweet are chiefly employed in cutting away the
wood towards the edges, about one-eighth | ing against the side of the block, in the of an inch below the subject. The gouge manner just represented, allows the
blade to move backwards and forwards FIG. 42.
with a slight degree of pressure against it, and in case of a slip, it is ever ready to check the graver's progress. This mode of resting the thumb against the edge of the block is, however, only applicable when the cuts are so small as to
allow the graver, when thus guided and IS similar to an ordinary carpenter's controlled, to reach every part of the gouge, except that it is solid, being a subject. When the cut is too large to round bar, with the end ground off at admit of this, the thumb then rests upon an angle. The other articles required the surface of the block, as in Fig. 45, are, a sand-bag, on which to rest the block whilst engraving it; an agate
Fig. 45. burnisher, and a dabber, which are used for taking proof-impressions of the woodcut; an oil stone, and eye-glass with shade.
Holding the Graver. — Engravers on copper and steel, who have much harder substances than wood to cut, hold the graver with the forefinger extended on the blade beyond the thumb, Fig. 43, so Fig. 43.
still forming a stay to the blade of the graver, and checking at once any accidental slip.
Wood.—For large coarse cuts, such as
are often used for trade purposes, sycathat by its pressure the point may be
more and pear tree may be employed, pressed into the plate. As boxwood,
but are too soft and irregular in the however, is much softer than these me
grain to bear fine work. Boxwood, either tals, and as it is seldom or perfectly | English, American, or from the Levant, equal hardness throughout, it is neces
is the favourite material; it should be of sary to hold the graver in a different
a light straw yellow colour, free from manner, and employ the thumb at once
black or white spots or red streaks, as as a stay or rest for the blade, and as a
these indicate a soft wood, which check upon the force exerted by the palm
crumbles away under the graver. The of the hand, the motion being chiefly
small wood is generally tolerably free FIG. 44.
from blemishes. When a large cut is wanted, if a block of the required size is not at hand, several smaller blocks are sometimes bolted together. The blocks are cut a trifle thicker than the height of type, about an inch ; they are then planed, brought to a very smooth surface, and gauged to the exact height of type. These blocks should be kept for some months until they are properly
seasoned. guided by the forefinger, as is shown in Drawing on the Block.—The polished Fig. 44. The thumb, with the end rest- | boxwood will not toke the pencil without a slight wash is first laid on it. A must then be cut off, and carefully thin wash of Chinese white mixed with brought to a smooth surface, level with water, some very fine Bath brick dust, or the rest of the block; if this is not done the white scrapings of glazed cardboard, the plug will be visible on the print. mixed with water, and gently rubbed off If the error to be remedied happens to when dry with the palm of the hand, be in a long line, a hole must be drilled gives a capital surface for the black-lead at each end, and the wood between the pencil. Make a tracing of the outline of two holes removed by small chisels, the the subject, place a sheet of transfer hollow space being filled up in a similar paper on the block, lay the tracing over way to that already described. it, and go carefully over every line with Lithography.-The following are a sharp point. It must be remembered the principles on which the art of lithothat the woodcut will be reversed when graphy depends ; - the facility with printed. The outlines must be corrected, which calcareous stones imbibe water; and completed, by a hard sharp-pointed the great disposition they have to adhere HHHH pencil; the tints may after- | to resinous and oily substances; and the wards be filled in by a softer pencil, or affinity between each other of oily and thin washes of Indian ink, to show the resinous substances, and the power they effect of light and shade. Caution must possess of repelling water, or a body be taken to use these washes sparingly, moistened with water. Hence, when so as not to affect the wood. All parts drawings are made on a polished surface of the block, not being cut, must be kept of calcareous stone, with a resinous or covered up, so as to preserve the drawing oily medium, they are so adhesive that from injury, and the fine lines of the cut nothing short of mechanical means can from being blunted or broken. Smooth effect their separation from it; and whilst blue glazed paper is very good for this the other parts of the stone take up the purpose, as it reduces the glare from the water poured upon them, the resinous, or lamp.
oily parts, repel it. When, therefore, Proofs. — When the engraving is over a stone prepared in this manner, a finished, a proof may be taken in the coloured oily or resinous substance is following manner before blocking out the passed, it will adhere to the drawings cut, that is, before the superfluous wood made as above, and not to those parts of is cleared away ; — rub down a little the stone which have been watered. The printer's ink on a slab till it is fine and ink and chalk used in lithography are of smooth; take a little of this on a silk | a saponaceous quality; the former is predabber, and carefully dab the block until pared in Germany from a compound of sufficient ink is left upon the surface, curd or common soap, pure white wax, a without allowing any to sink below it. small quantity of tallow and shellac, and Lay a piece of India paper on the block a portion of lampblack, all boiled together, with about two inches margin all round; and, when cool, dissolved in distilled on this place a thin smooth card ; rub water. The chalk for the crayons used this over with the burnisher, taking care | in drawing on the stone is a composition not to shift the card or paper.
consisting of the ingredients above menPlugging.-If a slip, or mistake, occurs tioned. After the drawing on the stone in a woodcut, it may be remedied by the has been executed, and is perfectly dry, insertion of a plug. A hole must be a very weak solution of nitric acid is drilled in the block; if the error is a poured upon the stone, which not only small one the hole need not be deep, but takes up the alkali from the chalk or ink, if a large piece has to be inserted it must as the case may be, leaving an insoluble be deeper in proportion. A plug is cut, substance behind it, but lowers, to a of a round, taper shape; the small small extent, that part of the surface of end is inserted in the hole, and the plug the stone not drawn upon, thus preparing is driven down, without, however, using it to absorb water with greater freedom. too much force. The top of the plug Weak gum water is then applied to the