BITING.
27. =Bordering the Plate.=--This work took some time. Our young student,
impatient to see the transformation wrought by the acid, came back
without keeping me waiting for him.
"Hurry up! A tray, acid, and all the accessories!"
Instead of using a tray, I tell him, we can avail ourselves of another
method, which is used by many engravers, and which consists in bordering
the plate with wax. This wax,[6] having been softened in warm water, is
flattened out into long strips, and is fastened hermetically and
vertically around the edges of the plate, so that, when hardened, it
forms the walls of a vessel, the bottom of which is represented by the
design drawn with the point. To avoid dangerous leaks, heat a key, and
pass it along the wax where it adheres to the plate; the wax melts, and,
on rehardening, offers all possible guarantees of solidity. We now pour
the acid on the plate thus converted into a tray, and as we have taken
care to form a lip in one of the angles made by the bordering wax, it is
an easy matter to pour off the liquid after each biting. This proceeding
is useful in the case of plates which are too large for the tray.
Otherwise, however, I prefer a tray made of gutta-percha or porcelain.
28. =The Tray.=--Let us now install ourselves at this table, and let us
cover the margin and the back of the plate with a thick coat of
stopping-out varnish. As soon as the varnish is perfectly dry, we place
the plate into the tray standing horizontally on the table, and pour on
acid enough to cover it to the height of about a centimetre. This depth,
which is sufficient for biting, allows the eye to follow the process in
its various stages.
29. =Strength of the Acid.=--This acid is fresh, and has not yet been
used; bought at forty degrees, I mix it with an equal quantity of
water, which reduces it to twenty degrees. This is the strength
generally adopted for ordinary biting. Its color is clear, and slightly
yellow; but as soon as it takes up the copper it becomes blue, and then
green. As, in its present state, it would act too impetuously, I add to
it a small quantity of acid which has been used before. You may also
throw a few scraps of copper into it the day before using it; the old
etchers used for this purpose a copper coin, larger or smaller,
according to the volume of the bath.[7]
30. =Label your Bottles!=--One day, one of my pupils, having a bad cold,
did not notice the difference between the smell of the acid and that of
the turpentine, and so plunged a plate which he desired to bite, into a
bath of the latter fluid. "It's queer," he said, "this won't bite, and
yet the varnish scales off.... The lines keep enlarging, and run into
one another! What does this curious medley mean, which appears on the
plate?" It was simple enough. The spirits of turpentine had dissolved
the ground, and consequently the plate developed a shining and radiating
surface before the eyes of our wondering student, as if it had just left
the hands of the plate-maker.
Advice to those who are absent-minded, and who are liable to mistake
fluids which look alike for one another,--Label your bottles!
31. =The First Biting.=--Let us make haste now, I say to my pupil, to do
our biting. As the heat of the day abates, the acid becomes less active;
and besides, to judge by the delicate character of the original we are
to render, we shall need at least two or three hours, all told, for this
operation. The task before us consists in the reproduction of a given
work, the merit of which lies in the gradation in the various distances.
It needs time and attention to be able to carry all the necessary
processes successfully into practice.
It will be plain to you, from what I have just said, that the operation
you are about to engage in is one of the most delicate in the etcher's
practice. There is the plate in the acid; the liquid has taken hold of
the copper; but your sky must be light, and a prolonged corrosion would
therefore be hurtful to it. Hence we take the plate out of the bath,
pass it through pure water, so that no acid is left in the lines, and
cover it with several sheets of blotting-paper, which, being pressed
against it by the hand, dries the plate. We shall have to go through the
same process after each partial biting, because if the plate were moist,
the stopping-out varnish which we are going to apply to it would not
adhere.
32. =The Use of the Feather.=--You noticed the lively ebullitions on the
plate, which took place twice in succession. After the first, I passed
this feather lightly over the copper, to show you its use. Its vane
removed the bubbles which adhered to the lines. This precaution is
necessary, especially when the ebullitions acquire some intensity and
are prolonged, to facilitate the biting, as the gas by which the bubbles
are formed keeps the acid out of the lines. If these bubbles are not
destroyed, the absence of biting in the lines is shown in the proofs by
a series of little white points. Such points are noticeable in some of
the plates etched by Perelle, who, it seems, ignored this precaution.
33. =Stopping Out.=--The two rapid ebullitions which you saw may serve
you as a standard of measurement; the biting produced by them must be
very light, and sufficient for the tone of the sky. You may, therefore,
cover the entire sky with stopping-out varnish by means of a brush,
taking care to stop short just this side of the outlines of the other
distances. The importance of mixing lamp-black with your stopping-out
varnish to thicken it, comes in just here; because if it remained in its
liquid state, it might be drawn by capillary attraction into the lines
of those parts which you desire to reserve, and thus, by obstructing
them, might stop the biting in places where it ought to continue. Wait
till the varnish has become perfectly dry; you can assure yourself of
this by breathing upon it; if it remains brilliant, it is still soft,
and the acid will eat into it; but as soon as it is dry it will assume a
dull surface under your breath.[8]
34. =Effect of Temperature on Biting.=--Let us now return the plate to
the bath, to obtain the values of the other distances. The temperature
has a great effect on the intensity of the ebullitions, and it is hardly
possible to depend on it absolutely as a fixed basis on which to rest a
calculation of the time necessary for each biting, as its own
variability renders it difficult to appreciate the aid to be received
from it. In winter, for instance, with the same strength of acid, it
needs four or five times as much time to reach the same result as in
summer, so that on very hot days the biting progresses so rapidly that
the plate cannot be lost sight of for a single moment without risk of
over-biting.
[Illustration: Pl. I_a_.]
35. =Biting continued.=--We have now obtained several moderate
ebullitions, and as it would not do to exaggerate the tone of the
mountain in the background, it is time to withdraw the plate once more.
Uncover a single line by removing the ground, either with the nail of
your finger or with a very small brush dipped into spirits of
turpentine, to examine whether it is deeply enough bitten for the
distance which it is to represent. If the depth is not sufficient, cover
it with stopping-out varnish, and bite again. This is not necessary,
however, in our present case, and you may therefore stop out the whole
background. Remember, if you please, that the line must look _less_
heavy than it is to show in the proof; for you must take into account
the black color of the printing-ink. With your brush go over the edges
of the trees which are to be relieved rather lightly against the sky, as
well as over that part of the shadow in this tower which blends with the
light. There are also some delicate passages in the figure of the woman
in the foreground, in the details of the plants, and in the folds of
this tent (Pl. I_a_). Stop out all these, and do not lose sight of the
values of the original (Pl. II.). Make use of the brush to revarnish
several places which are scaling off on the margin and the back of the
plate. The temperature is favorable; the ebullitions come on without
letting us wait long, and the plate is bluing rapidly. I do not like to
see these operations drag on; in winter, therefore, I do my biting near
the fire. We soon acquire a passion for biting, and take an ever-growing
interest in it, which is incessantly sharpened by thinking of the result
to which we aspire. Hence the desire of constant observation, and that
assiduity in following all the phases of the biting-in.
I notice that the acid does not act on certain parts of your work; you
will find out soon enough what that means.
36. =Treatment of the Various Distances.=--"I am thinking just now of
what you told me in regard to the background:--that more work ought to
be put into it than into the foreground."
Nothing, indeed, is simpler. You understand that the background, which
is bitten in quite lightly, must show very delicate lines, while in the
middle distance and in the foreground the lines are enlarged by the
action of successive bitings. When it comes to the printing, the
quantity of ink received by these various lines will be in proportion to
the values which you desired to obtain, and in the proofs you will have
a variety of lighter or stronger tones, giving you the needed gradations
in the various distances. It follows from this that, if you had worked
too sparingly on the distances which receive only a light biting, you
could not have reached the value of the tone which you strove to get,
and if you had worked too closely on those parts which require continued
biting, you would have had a black and indistinct tone, because the
lines, which are enlarged by the acid, and consequently keep approaching
one another, would finally have run together into one confused mass,
producing what in French is called a _creve_ (blotch).
In an etching the space between the lines must be made to serve a
purpose; for the paper seen between the black strokes gives delicacy,
lightness, and transparency of tone.
37. =The Creve.--Its Advantages and Disadvantages.=--In very skilled
hands the _creve_ is a means of effect. If you wish to obtain great
depth in a group of trees, in a wall, in very deep shadows, you will
risk nothing by intermingling your lines picturesquely and biting them
vigorously. In this way you can produce tones of velvety softness, and
at the same time of extraordinary vigor. Similarly, you may strike a
fine note by means of running together several lines which, if
sufficiently bitten, will form but a single broad one of great solidity
and power. It is, indeed, only the exaggeration of this expedient,
which, by unduly enlarging the limits of the broad line just spoken of,
and thus producing a large and deep surface between them, constitutes
the _creve_ properly so called; the printing ink has no hold in this
flat hollow, and a gray spot in the proof is the result. I have warned
you of the accident; later on you shall hear something of the remedy. We
will now continue our biting. Plunge your plate into the bath again, if
you please.
38. =Means of ascertaining the Depth of the Lines.=--"My dear sir, I see
that my drawing turns black; it disappears almost entirely, and is lost
in the color of the ground.[9] I am quite perplexed. My mind endeavors
to penetrate beneath this varnish, so as to be able to witness the
mysterious birth of my _oeuvre_. See these violent ebullitions! What
do you think of them?"
Let them go on a moment longer, and then withdraw your plate. We have
now arrived at a point where the eye cannot judge of the work of the
acid as easily as before; henceforth we must, therefore, examine the
depth of our bitings by uncovering a single line, as, for instance, this
one here in the ground. Or we may even lay bare, by the aid of spirits
of turpentine, a part of the foreground, provided, however, that we must
not forget to cover it again with the brush. This will give us an idea
of the total effect so far produced by the biting, and we can then
regulate the partial bitings which are still to follow, either by a
comparison of the time employed on those that have gone before, or by
the intensity of the ebullitions, the action of which on the copper we
have already studied. You perceive that, while it is difficult to fix a
standard of time for the bitings at the beginning of the operation, it
is yet possible to calculate those to come by what we have so far done.
39. =The Rules which govern the Biting are subordinated to various
Causes.=--In reality, it is impossible to establish fixed rules for the
biting, for the following reasons:--
1. Owing to the varying intensity of the stroke of the needle. The
etcher who confines himself to gently baring his copper must bite longer
than he who attacks his plate more vigorously, and therefore exposes it
more to the action of the acid.
2. Owing to the different quality of the plates.
3. Owing to the difference in temperature of the surrounding air:--of
this we have before spoken.
4. Owing to difference of strength in the acid, as it is impossible
always to have it of absolutely the same number of degrees. At 15 deg.
to 18 deg. the biting is gentle and slow; at 20 deg. it is moderate;
at 22 deg. to 24 deg. it becomes more rapid. It would be dangerous to
employ a still higher degree for the complete biting-in of a plate,
especially in the lighter parts.
40. =Strong Acid and Weak Acid.=--It is, nevertheless, possible to put
such strong acid to good service. A fine gray tint may, for instance,
be imparted to a well-worked sky by passing a broad brush over it,
charged with acid at 40 deg. But the operation must be performed with
lightning speed, and the plate must instantly be plunged into pure
water.
As a corollary of the fourth cause, it is well to know that an acid
overcharged with copper loses much of its force, although it remains at
the same degree. Thus an acid taken at 20 deg., but heavily charged with
copper from having been used, will be found to be materially enfeebled,
and to bite more slowly than fresh acid at 15 deg. to 18 deg. To continue
to use it in this condition would be dangerous, because there is no longer
any affinity between the liquid and the copper, and if, under such
circumstances, you were to trust to the appearance of biting (which
would be interminable, besides), you would find, on removing the
varnish, that the plate had merely lost its polish where the lines ought
to be, without having been bitten. It is best, therefore, always to do
your biting with fresh acid, constantly renewed, as the results will be
more equal, and you will become habituated to certain fixed conditions.
Some engravers, of impetuous spirit and impatient of results, do their
biting with acid of a high degree, while others, more prudent, prefer
slow biting, which eats into the copper uniformly and regularly, and
hence they employ a lower degree. In this way the varnish remains
intact, and there is not that risk of losing the purity of line which
always attends the employment of a stronger acid.
41. =Strength of Acid in relation to certain Kinds of Work.=--Experience
has also shown that, with the same proportion in the time employed, the
values are accentuated more quickly and more completely by a strong than
by a mild acid; this manifests itself at the confluence of the lines,
where the acid would play mischief if the limit of time were
overstepped.
Another effect of biting which follows from the preceding, is noticeable
in lines drawn far apart. Of isolated lines the acid takes hold very
slowly, and they may therefore be executed with a cutting point and
bitten in with tolerably strong acid.
The reverse takes place when the lines are drawn very closely together;
the biting is very lively. Work of this kind, therefore, demands a
needle of moderate sharpness and a mild acid.
Hence, interweaving lines and very close lines are bitten more deeply by
the same acid than lines drawn parallel to each other, and widely
spaced, although they may all have been executed with the same needle.
If, in an architectural subject, you have drawn the lines with the same
instrument, but far apart on one side, and closely and crossing each
other on the other, you must not let them all bite the same length of
time, if you wish them to hold the same distance. It will be necessary
to stop out the latter before the former, otherwise you will have a
discordant difference in tone. There will be inequality in the biting,
but it will not be perceptible to the eye, as the general harmony has
been preserved. (See Pl. IV. Fig. 1.)
In short, strong acid rather widens than deepens the lines; mild acid,
on the contrary, eats into the depth of the copper, and produces lines
which are shown in relief on the paper, and are astonishingly powerful
in color. This is especially noticeable in the etchings of Piranesi, who
used hard varnish.
42. =Last Stages of Biting.=--But let us return to our operation. You
noticed that I allowed your plate to bite quite a while; this was
necessary to detach your foreground and middle-ground vigorously from
the sky and the background. You may now stop out the trees, the tower,
and the tent in the middle-ground, and the vertical part of the bridge,
which is in half-tint, and then proceed. Note that the number of bitings
is not fixed, but depends on the effect to be reached.
"In that case it is to be hoped, for the sake of my apprentice hands,
that I shall never have many bitings to do. Just look at my fingers!
They are in a nice state. The prettiest yellow skin you ever saw!"
Oh, don't let that color trouble you; it will be all black by to-morrow.
"Much obliged to you for this bit of consolation!"
Besides, it will take you a week to grow a new skin. In future you must
soak your fingers in pure water whenever you have got them into the
acid. You might have used india-rubber finger-gloves; they are excellent
to keep the hands clean, but it is not worth while to trouble about them
for the present, as we are almost done.[10] I think you may now stop out
all that remains, with the exception of the darkest places in the
foreground, to which we must give a final biting.
There! Now we've got it! Withdraw your plate for the last time, and as
there are some very widely spaced lines in this tree in the foreground,
you will risk nothing by giving them a final touch with pure acid. The
strongest accent in the landscape rests on this spot; it determines the
color of the whole. By this application of pure acid we shall get a
vigorous tone, a powerful effect.
I may as well tell you here that it is sometimes advisable to add a
small quantity of pure acid to the bath towards the end of the
operation, so as to increase the activity of the biting on certain parts
of the plate without running into excess. But as the place now under
consideration is restricted, we shall adopt another means, so as to
limit the action of the acid to the given point. See here: I let fall a
few drops; the pure acid eats into the copper with great vehemence; the
metal turns green, and the ebullition subsides. Now take up the
exhausted liquid with a piece of blotting-paper, and let us commence
again. Under these newly added drops of fresh acid, the varnish is ready
to scale off, the lines sputter, and assume a strange yellow color;
these golden vapors announce that the operation is finished.
What follows, is the task of the printer; his press will tell us whether
we have won, or whether we have been mated. Clean the plate with spirits
of turpentine, using your fingers, or with a very clean old rag (calico,
if possible), if you are afraid to soil your hands. Be sure to have the
plate well cleaned, but take care not to scratch it.
The acid, which may be of use hereafter, we will turn into a glass
bottle with a ground stopper, and will store it in some safe place.