A Method and Material for Rendering the Coating of Fuses Incombustible.
Year: 1886

page_text: Date of Application, 6th Oct., 1886.
Complete Left, 5th July, 1887.
Complete Accepted, 12th Aug., 1887.
PROVISIONAL SPECIFICATION.
A Method and Material for Rendering the Coating of Fuses
Incombustible.
1, GEORGE JOHN SMITH, of Tuckingmill in the County of Cornwall, Fuse
Manufacturer, do hereby declare the nature of this invention to be as follows:-
My invention relates to means of rendering incombustible the tape or other fabric
which forms the coating of fuses so that while the internal part of the fuse serves to
convey fire for igniting blast or other charges, the exterior coating remains unconsumed
and prevents communication of the fire to gas or other external materials.
For this purpose, I impregnate and cover the coating with a varnishing material
which consists in part of the varnish ordinarily used for protecting fuses, with the
addition of about 25 per cent. of borax pulverised and gradually mixed at a temperature
of about 200° Fahr. with the other ingredients. When more complete incombustibility
is desired without regard to cost, I substitute for the borax a silicate or a tungstate of
soda, or a silicate of aluminium. These substances may be employed in various
mixtures and proportions. In some cases I suspend in the liquid varnish powdered or
flocculent asbestos which adheres with the varnish to the coating.
11
Ja of Ona 1886
ABEL & IMRAY,
28, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: A Method and Material for Rendering the Coating of Fuses
Incombustible.
I, GEORGE JOHN SMITH of Tuckinginill in the County of Cornwall, Fuse
Manufacturer, 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 means of rendering incombustible the tape or other fabric
which forms the coating of fuses, so that, while the internal part of the fuse serves to
convey fire for the ignition of blasting or other explosive charges, the exterior coating
is so constructed and protected as to prevent communication of the internal fire of the
fuse to gas or other combustible substances outside, and also to prevent the fuse from
being accidentally ignited from without at any part of its length. For this purpose,
I apply to the tape or other fabric covering of the fuse a coat or several coats of a
specially prepared varnishing material consisting of various ingredients, some of which
have the effect of preventing communication of fire through the substance of
which they form a part. A suitable mixture for the purpose consists of about 35 per
cent. by weight of borax, about 26 per cent. of glue, from 8 to 9 per cent. of china
clay, and from 30 to 31 per cent. of water. The glue is separately dissolved in water
and the borax is added to the solution; the china clay is made into a thick paste with
a portion of the water, and this being mixed with the glue and borax solution, the
whole is heated to boiling point and kept in agitation for some time, while the heat is
maintained. The mixture is then allowed to settle, and the supernatant liquor is
decanted off, leaving a precipitate which constitutes the required varnish.
In this varnish I immerse the ordinary spun fuse and then, after covering the fuse
helically with tape in the usual way, I immerse it again in the varnish. In some
cases; in order to give a smooth finished appearance to the fuse, I tape it again and
then immerse it in a white varnish consisting principally of china clay, glue and water.
Instead of using borax as above described, other substances may be employed as
ingredients of the varnish, such, for instance, as tungstate of soda or silicate of
alumina.
Ammonium sulphate may also be used in addition to the substances mentioned, the
more effectually to prevent communication of fire, but, as this substance does not
readily compound with the other ingredients to form a varnish, I apply it by soaking
the tape in a strong solution of it, and use the tape thus impregnated when dried as a
covering to the already varnished fuse. The fuse, as it leaves any of the varnish baths
to which it is subjected, may be drawn through flocculent asbestos which, adhering to

page_text: it as a coating, forms an additional safe guard against communication of fire
through it.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. The method of rendering the coating of a fuse incombustible by means of a
varnish compounded and applied substantially as herein described.
2. The herein described manufacture of varnish for rendering the coating of fuses
incombustible.