Page 267 - My FlipBook

SOLDERS AND SOLDERING. 255

melted under a laver of charcoal and stirred well before
pouring. \\ lien a solder melts above red lieat it is called
a hard solder. When it melts Ijelow this point it is known
as a soft solder. It is the former class, those managed with
the blow^pipe or other flame, which we shall consider here.
The soft solders are liown and directed by a hot iron known
as a soldering iron.
Soldering, as has been indicated, refers to the union of
two or more pieces of metal, by a more fusible metal or
alloy. The several conditions necessary for successful sol-
dering are:
) Contact of the metals to be. united.
( 1
(2) Clean surfaces over which the solder is to flow.
(3) A freely flowing solder.
(4) A flux to facilitate the operation.
(5) The proper amount and distribution of heat.
Each of the above conditions, though apparently simple,
is of much importance. If they are carefully followed the
operation is not a difficult one. The cjuantity of solder
used should always be reduced to the minimum. Outside
of the question of economy it is undesirable to have a con-
siderable amount of excess of solder as it is difficult to
remove in finishing the piece, and it is also liable to cause
fracture of porcelain teeth or otherwise injure the case, from
contraction on cooling.
Cleanliness is one of the conditions. This refers to the
solder itself, as well as the metals to be soldered. All should
be free from oxidation, carbon, plaster of paris or other
foreign substances. The removal of slight oxidation is
accomplished by the flux used. Borax being generally em-
ployed for this purpose, and when melted by the flame dis-
solves any slight oxidation and protects the metallic surface
from further oxidation by protecting it from the atmos-
phere. The management of the flaine also can not be too