an be either aluminum, white metal, zinc or any
other metal having a low melting-point. This completes the
equipment with the exception of one or two simple devices which
will now be described.

** II - How to Make a Mold [96]

Having finished making the flask and other equipment, as
described, everything will be ready for the operation of molding.
It would be well for those who have never had any experience in
this line to visit a small brass foundry, where they can watch the
molders at work, as it is much easier to learn by observation; but
they must not expect to make a good mold at the first trial. The
first attempt usually results in the sand dropping out of the cope
when it is being lifted from the drag, either because of
insufficient ramming around the edges or because the sand is too
dry.

A good way to tell when the sand is moist enough is to squeeze it
in the hand. If it forms into a cake and shows all the
finger-marks, it has a sufficient amount of moisture, but if it
crumbles or fails to cake it is too dry. An ordinary watering-pot
will be found useful in moistening the sand, but care should be
taken not to get it too wet, or the hot metal coming in contact
with it when the mold is poured will cause such rapid evaporation
that the mold will "boil" and make a poor casting. A little
practice in this operation will soon enable the molder to
determine the correct amount of moisture.

When molding with sand for the first time it will be necessary to
screen it all before using it, in order to remove the lumps, and
if water is added, the sand should be thoroughly shoveled until
the moisture is evenly distributed. The sand is then ready for
molding.

The operation of making a mold is as follows: The lower half of
the flask, or "drag," and the pattern to be molded are both placed
on the cover board as shown at A. A quantity of sand sufficient to
completely cover the pattern is then sifted into the drag, which
is then filled level with the top with unscreened sand. This is
rammed down slightly with the rammer, and then more sand is added
until

[Illustration: Fig,. 3-Making a Mold]

it becomes heaped up as shown at B. It is then rammed again as
before.

It is impossible to describe just how hard a mold should be
rammed, but by observing the results the beginner can tell when a
mold is too hard or too soft, and thus judge for himself. If the
sand falls out of the flask when lifting the cope, or if it