Instjlators are attached to their pins in a great variety of ways. All sorts
of cements for the purpose have been put on the market, some of which are unsatis-
factory because they attack the pin chemically and others because their co-
efficient of expansion differs from that of porcelain. A good method consists
in the employment of hemp soaked in linseed oil or in red-lead. The mounting
however, requires training, skiU, and reliability, and it is not advisable, therefore,
to leave it to unskilled labourers to fill in their time on. The safest plan is to
obtain the insulators ready mounted on their pins from the porcelain factory.
The PorzeUanfabrik Hermsdorf state that a great many insulator defects which
they have investigated have turned out to be due to faulty mounting and the use
of unsuitable materials for it. They have therefore circu-
lated the following instructions.
