Of Niello,[279] and how by means of this process we have Copper
Prints; and how Silver is engraved to make Enamels over bas-relief,
and in like manner how Gold and Silver Plate is chased.[280]
§ 103. _Niello Work._
Niello, which may be described as a design traced and painted on silver,
as one paints and traces delicately with the pen, was discovered by the
goldsmiths as far back as the time of the ancients, there having been
seen in their gold and silver plates incisions made by tools and filled
up with some mixture.[281] In niello the design is traced with the
stylus on silver which has a smooth surface, and is engraved with the
burin, a square tool cut on the slant like a spur from one of its angles
to the other; for sloping thus towards one of the corners makes it very
sharp and cutting on the two edges, and its point glides over the metal
and graves extremely finely.[282] With this tool is executed all graving
on metal, whether the lines are to be filled or are to be left open,
according to the pleasure of the artificer. When therefore they have
finished their graving with the burin, they take silver and lead and
fuse them into one substance over the fire; and this when completely
amalgamated is black in colour, very friable, and extremely
fusible.[283]
The next process is to pound this substance and put it over the engraved
silver plaque which must be thoroughly clean, then to bring it near to a
fire of green wood, blowing with the bellows that the rays of the fire
may strike upon the niello, which by virtue of the heat melts and flows
filling up all incisions that the graver has made. Afterwards when the
silver has cooled, the worker proceeds to remove carefully the overplus
with scrapers, and with pumice stone to grind it away little by little,
rubbing it with the hands and with a leather till it is reduced to the
true flat and the whole is left polished. The Florentine Maso Finiguerra
worked most admirably in this craft in which he was really
extraordinary, as is testified to by some paxes[284] of niello in San
Giovanni of Florence that are esteemed wonderful.
§ 104. _The Origin of Engraving._
[Illustration:
PLATE XIII
SPECIMEN OF NIELLO WORK
A ‘Pax’ formerly in the Baptistry, and now in the National Museum,
Florence
]
From this graving by the burin are derived the copper plates from which
we see to-day so many impressions throughout all Italy of both Italian
and German origin. Just as impressions in clay were taken from silver
plaques before they were filled with niello, and casts pulled from these
in sulphur,[285] in the same manner the printers found out the method of
striking off the sheets from the copper plates with the press, as we
have seen printing done in our own days.
§ 105. _Enamels over Reliefs._
See now another sort of work in silver and in gold, commonly called
enamel, a kind of painting intermingled with sculpture, suitable for
lining the bottom of pieces intended to hold water.[286] This when
worked on gold, needs the very finest gold; and when on silver, the
silver at least of the quality of the giulio.[287] The following method
is necessary in order that the enamel may remain in its place and not
run beyond its proper limits. The edges of the silver[288] must be left
so fine that when looked at from above they escape the eye. In this way
is made a flat relief contrary to the other kind,[289] in order that
when the enamels are put over it, it may take its darks and lights from
the height and depth of the intaglio. Then glass enamels of various
colours are picked out and carefully fixed with the hammer;[290] they
are kept in little bowls filled with clear water, separated and distinct
one from the other. Those which are used with gold are different from
those that serve for silver[291] and they are worked in the following
manner. The enamels are lifted out separately with the most delicate
little silver shovel and spread in their places with scrupulous
cleanliness, and this is done over and over again, according as the
enamel adheres properly, and so with all the quantity that is needed at
the time. This done, an earthenware receptacle, made on purpose, is
prepared; it must be perforated all over and have a mouthpiece in front,
then the muffle, which is a little perforated earthenware cover that
will prevent the charcoal falling from above, is introduced into this
receptacle, and above the muffle the space is filled up to the top with
oak charcoal kindled in the ordinary way. In the empty space which is
left under the aforenamed cover the enamelled object is placed on a very
thin iron tray to feel the heat gradually and is kept there long enough
to admit of the enamels melting, when they flow all over almost like
water. Which done, it is allowed to cool, and then with a ‘frassinella,’
that is, a stone for sharpening iron tools, and with sand such as is
used for drinking glasses moistened with clear water, it is rubbed till
it becomes perfectly level. When the process of removing all superfluity
is finished, the object is placed in the actual fire, to be melted a
second time in order that the whole surface may become lustrous.[292]
Another sort is made by hand, and polished with Tripoli plaster (powder)
and a piece of leather, but of this there is no need to make
mention.[293] I have however described the above because being, like the
other processes, of the nature of painting it seemed to come into our
subject.