Dodgeville chronicle. [volume] (Dodgeville, Wis.) 1862-current, 1870-10-21
Clements and How to Use Them.

A great deal has been written concern
ing different cements, and indeed our Pc
riodicals are full of recipes on this sub
ject. But (says the English Mechaaaic), it
will be found that the information given
is rather in regard to the materials used
in compromising these cements than in
regard to the manner of using them.
And it is unquestionably true that quite
as much depends upon the manner in
which cement is applied as upon the
cement itself. The best cement that ever
was compounded would prove entirely
worthless If improperly applied. We have
hundreds of recipes for Clues, pastes, and
cements of different kinds, and yet the
public is constantly on the qui 05vs for
new ones, and no more acceptable recipe
can be sent to our popular journals than
one for new cement. Now, the truth is,
that we have cements which answer eve
ry reasonable demand, when they are
properly prepared and properly used.
Good common glue will unite two pieces
of wood so firmly that the tibers will part
from each other rather than from the ce.
menting material; two pieces Of glass
can be so joined that they will part any
where rather than on the line of union
glass can be united to metal, metal to
metal, stone to stone, and all so strongly
that the joint will certainly not be the
weakest part of the resulting mass What
are the rules to be observed in effectipg
this?
The first point that demands attention
Is to bring the cement itself into intimate
contact with the surface TO be united. If
glue is employed, the surface should be
made so warm that the melted glue will
not be chilled before it has time to effect
thorough adhesion. The same is more
eminently true in regard to cements that
are used in a fused state, such as mixtures
of resin, shellsc, and similar materials.
These mixtures will not adhere to any
substance unless the latter has been heat
ed to nearly or quite the fusing point OF
the cement used. This fact was quite
familiar to those who used sealing wax in
old days. When the seal was used rapid
Iy, so as to become heated, the sealing
| wax stuck to it with firmness that was
annoying--so much so that the impress.
sion was, in general, destroyed-from the
simple fact that the sealing wax would
rather part in its own substance than al
the point Of adhesion to the stamp. Seal
| ing wax, or ordinary electrical cement, is q
very good agent for uniting metal to glass
| or stone, provided the masses to be united
are made SO hot as to fuse the cement
but if the cement is applied to them while
| they are cold, it will not stick at all
| This fact is well known to those itinerant
vendors of cement for uniting earthen.
ware. BY heating two pieces of deli SO
that they will fuse shellac, they are able
| to smear them with a little of this gum
and join them so that they will rather
break at any other part than along the
line of union. But although people con
| stantly see the operation performed, and
buy literally of the cement, it will be
found that, in nine cases out of ten, the
cement proves worthless in the hands oil
| the purchasers, simply because they dc
not know how to use it. They are afraid
to heat q delicate glass or porcelain yes.
sci to sufficient degree, and thev are apt
| to use too much of the material, and the
result is failure.
The great obstacles to the junction OF
any two surfaces are air and dirt. The
former is universally present, the latter is
due to accident or carelessness. All sur.
faces are covered with o thin adherine
layer of air, which it is difficult to re-
| move, and which, although it may at first
sight appear improbable, bears relation
to the outer surface of most bodies differ.
| emit from that maintained by the air of q
few lines away. The reality of the ex.
istence of this aohering layer of air is
well known to all those who are familiar
with electrotype manipulation 1t is also
seen in the case of highly polished metals
which may be immersed in We ter without
becoming wet Unless this adherine
layer of air is displaced, the cement can.
| not adhere to the surface to which it is
applied, simply because it cannot come in.
to contact with it. The most Efficient
agent in displacing this air is heat
Metals warmed to a point little above
1900, become instantly and completely
wet when immersed in water. Hence
for .cements that are used in fused con.
dition, heat is the most efficient means Of
bringing them in contact with the sur.
faces to which they are to be applied. In
the case of glue, the adhesion is best at.
tanned by moderate pressure and friction
Another very important point ia to use
as little cement as possible. When the
surfaces are separated by large mass OF
cement, we have to depend upon the
strength of the cement itself, and not
upon its adhesion to the surfaces which
81 .7co1 fo apd II, oa,,, ~, q,