[b-hebrew] Lost wax casting Exo 32:4
George F. Somsel
gfsomsel at juno.com
Mon Aug 16 06:50:37 EDT 2004
On 16 Aug 2004 02:57:16 -0000 "David N. da Silva"
<huyxh8s02 at sneakemail.com> writes:
> This is the first of a few "alternative readings" for which I would
> appreciate comments; especially from anyone whose grammar is better
> than mine (which is anyone).
> In JPS 1917, Exo 32:4 begins
> And he received it at their hand, and fashioned it with a graving
> tool, and made it a molten calf;
> I presume that in the second millennium, one would make a golden
> figurine by using the lost wax method. "Tsuwr," which here gets
> translated "fashioned" usually means bind or confine or besiege.
> And confine is just what you do with the wax form before casting.
> Accordingly, I propose:
> ... and he took from their hands. He worked with a stylus, and
> encased it, and made a cast bull-calf.
> I didn't want to say explicitly that wax was used, since there is no
> mention of wax. The author (the Elohist) would presumably have
> thought that his mention of tsuwr was sufficient to indicate the
> method used, since there is no binding or confining in any other
> method which could have been used.
> David Nunes da Silva
> p.s. I looked at many translations, but could not find any that
> translated this passage in a way that suggested the lost wax method.
> If someone can tell me that the Hebrew clearly rules out the idea
> that lost wax casting was meant, I would appreciate it - and also if
> my proposed translation is defective for any other reason.
I'm not sure that grammar is much involved here. I think rather it has
to do with some knowledge of the technology of the time.
I doubt that the lost wax method would have been used. I rather imagine
that it would have been a sand cast (assuming it to be historical though
I rather think it is a polemic against the Northern Kingdom.
I INTRODUCTION Founding, process of producing metal objects, called
castings, by pouring molten metal into a hollow mold, usually made of
sand. The founding process itself is sometimes called casting. It is an
ancient art that is still used extensively, although it has been
supplanted to some extent by other methods, such as die-casting, forging,
extrusion, machining, and rolling. See Iron and Steel Manufacture;
Founding involves three separate operations: first, a wood, plastic, or
metal pattern intended as a replica of the finished object is made; a
hollow mold is then made by packing sand around the pattern and removing
the pattern; finally, molten metal is poured into the mold.
In cases where a small number of castings are to be made the foundry
pattern is usually of varnished wood, but in the production of a large
number of castings, it may be plastic, cast iron, steel, aluminum, or
other metal. The pattern differs in two important ways from the original:
its dimensions are slightly enlarged to compensate for the shrinkage of
the casting as it cools, and patterns of hollow objects have projections
that correspond to the cores (described below). Although patterns can be
made in one piece, a complicated casting is easier to remove from the
mold if it consists of two or more parts. Patterns of objects with
straight sides are usually made with a slight taper for the same reason.
Pattern parts are fitted with matching pegs and holes to ensure precise
alignment when assembled. Molding a pattern and pouring a casting can be
understood through a description of a simple casting such as a pipe with
a flanged end (Figure 1). The pattern for this casting is shown in Figure
2. The molds for most castings are prepared in flasks (wooden boxes
without top or bottom) equipped with pegs or other devices that enable
the boxes to occupy the same relative position when fitted together
(Figure 3). The lower box is called the drag, and the upper one the cope.
In making the mold, the flat portion of half of the pattern is placed on
a flat surface and the drag is invested and placed around it. Molding
sand is poured into the flask and rammed down until the entire flask is
filled. The flask is then turned over and the other half of the pattern
is set in place, as in Figure 4. A layer of special dry sand, called
parting sand, is sprinkled on the surface of the flask; then the cope is
placed in position, filled with sand, and rammed. The two halves of the
mold are then taken apart and the pattern is drawn or removed. One or
more gates or pouring holes are then pierced through the sand of the
cope, as are smaller holes called risers that carry away part of the
steam formed when the hot metal is poured into the mold.
Finally, the core, the part of the mold that forms the hollow within the
casting, is prepared. In the pipe shown in Figure 1, this core takes the
form of a simple cylinder, but a complex casting may require one or more
intricately shaped cores. The cores are formed in divided core boxes that
serve as patterns. After forming they are baked in an oven until they are
strong enough to be handled. The core is placed within the mold (Figure
5), and the other half of the mold is replaced. It is now ready for
pouring. Having been melted in a furnace, the metal is hand-poured from a
crucible for small castings or, in most cases, from a large dipper or
bucket carried by a crane or special car until the mold is completely
filled to the top of the gate.
After the casting has cooled within its mold, they both are shaken out of
the flasks, and the mold is broken. The rods of metal formed in the gates
and risers must be sawed off or otherwise removed.
The sand used in founding contains sufficient clay to make it cohesive
when slightly moistened before use. Parting sand is used to make the
flasks come apart cleanly when separated; this sand is dry and contains
little or no clay. Sand is used for molds because it permits a certain
amount of vapor and gas to escape when the casting is poured. For metals
with low melting points, such as brass, it is possible to use solid
molding materials such as plaster of Paris. Such moldsand metal
moldshave smoother surfaces than sand molds, and thus produce castings
with finer detail and finish. They cannot, however, be used in casting
iron or steel. Many variations and special techniques are involved in
ordinary founding. In manufacturing, making two or more castings in a
single mold is frequently desirable. Patterns of objects with overhanging
parts may be made with removable pattern portions so that the pattern may
be drawn from the mold piece by piece without disturbing the sand. In
casting such machine parts as gears, in which the rim must be as tough as
possible, pieces of iron or steel called chills are sometimes placed in
the mold around the rim. The chills conduct heat rapidly, permitting the
portion of the casting near them to harden quickly, thus toughening the
metal. Large wheels and gears are sometimes cast without flasks, in beds
of sand directly on the foundry floor. In such cases, the form of the
wheel rim is carved directly from sand, and cores are placed in the mold
for forming the hub and spokes.
Encarta Encyclopedia 2001
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