Improvements in Insulation for Electric Conductors.
Year: 1889

page_text: COMPLETE SPECIFICATION.
Improvements in Insulation for Electric Conductors.
I, CHARLES THELISMAR SNEDEKOR, of St. Louis, Missouri, United States of
America, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement :-
My invention relates to the insulation of electric conductors and other metallic
articles and substances, and it consists in a fire proof coating or covering the particular
construction of which is set forth in the following description and claims.
Many experiments have been made looking to the attainment of the results accom-
plished by my construction, but as far as I am aware, with only partial success,
many of the conductors, when insulated in the way proposed, being incapable
of bending without cracking or breaking the coating and thus destroying the
insulation.
By my improvement I am able to produce an insulated cable wire, or other
similar conductor, which has all the flexibility of the original conductor, and which at
the same time, is able to resist the action of fire.
In order that others may understand the nature of my said invention and the
manner of making and applying the same I will now proceed to describe it.
The wire, cable or other conductor to be insulated is first covered with a coating
of liquid shellac, and before this is dry, a coating or covering is applied to the conductor
consisting of some fibrous material, such as cotton, jute, silk or other similar substance
which has been saturated in a strong solution of alum.
This coating is then allowed to become perfectly dry, after which a liquid glue of
any preferred kind is applied, upon which, when hardened, I spread a thick coat
of heavy varnish.
While this varnish is yet damp a dust is applied consisting preferably of about four
parts of powdered or ground glass, one part powdered alum and one part powdered
asbestos.
The conductor is then again covered with a fibrous coating which has been first
thoroughly saturated with a composition or paste consisting of linseed oil, litharge,
white lead; ground asbestos and alum. I again cover this with fibrous material which
has first been saturated with a solution of alum and allowed to dry. To this dry
fibrous coating I next apply a solution of any of the varnish gums dissolved in linseed
oil and before this coating hardens there is pressed into it a thin coat of asbestos
fibre.
When this is perfectly dry and hard the whole is thoroughly coated with varnish.
While I prefer to use all of the ingredients mentioned in the manner set forth,
some of the ingredients and parts mentioned may be omitted and yet good results
attained. For instance, the coating of glue may be omitted and the powdered glass
may be omitted from the dust coating, and the litharge or white lead may be left out
of the composition or paste without any great detriment to the insulation.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1. An insulating covering for electric conductors and other metallic substances
consisting of a coating of alum-saturated fibre secured to the article to be insulated
by shellac, a coat of varnish upon the said fibre, a powdered non-inflammable coating
upon the said varnish, a fibrous coating filled with a paste compound of a mineral
substance or substances, a coating of dry alum-saturated fibrous material, an asbestos
covering and an outer coating of varnish, substantially as described.

page_text: 2. An insulating covering for electric conductors and other metallic substances,
consisting of a coating of alum-saturated fibrous material secured to the article to be
insulated, by shellac, a coat of varnish upon the said fibrous material, a powdered
non-inflammable coating upon the said varnish, a fibrous coating filled with a paste
compound, of a mineral substance or substances, a coating of dry alum-saturated
fibrous material, a coating of gum and oil, an asbestos covering and an outer coating
of varnish, substantially as described.
3. An insulating covering for electric conductors and other metallic substances
consisting of a coating of alum-saturated fibrous material secured to the article to be
insulated by shellac or its equivalent, a coating of glue, a coat of varnish upon the
glue when hardened, a coating of non-inflammable substance upon the said varnish, a
fibrous coating filled with a paste compound of a mineral substance or substances, a
coating of dry alum-saturated fibrous material a coating of gum and oil, an asbestos
covering and an outer coating of varnish, substantially as described.
4. An insulating covering for electric conductors and other metallic substances,
consisting of a coating of alum-saturated fibrous material secured to the article to be
insulated by shellac or its equivalent, a coating of glue, a coat of varnish upon the
glue when hardened, a non-inflammable coating consisting of a composition of
powdered or ground glass, powdered alum and ground asbestos, a fibrous coating filled
with a paste compound of a mineral substance or substances, a coating of dry alum-
saturated fibrous material, a coating of gum and oil, an asbestos covering and an outer
coating of varnish, substantially as described.
5. An insulating covering for electric conductors and other metallic substances
consisting of a coating of alum-saturated fibrous material, secured to the article to be
insulated by shellac or its equivalent, a coating of glue, a coat of varnish upon the
glue, a coating of non-inflammable substance or substances, a fibrous coating filled
with a paste compound composed of litharge, ground asbestos, alum and oil, a coating
of dry alum-saturated fibrous material, a coating of gum and oil, an asbestos covering
and an outer coating of varnish, substantially as described.
Dated the aut
1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.