An Improved Process of Manufacturing Mantles for Incandescent Burners.
Year: 1896

page_text: Date of Application, 9th Sept., 1896-Accepted, 31st Oct., 1896
COMPLETE SPECIFICATION.
An Improved Process of Manufacturing Mantles for Incandescent
Burners.
I, HANS WELLSTEIN, of 8, Wörtherstrasse, Berlin in the Empire of Germany,
Engineer, 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 :-
The manufacture of the mantles at present employed for incandescent burners is
always as is well known somewhat difficult and inconvenient because the fabric
employed for the purpose has in all cases to be subjected after completion to a
repeated thorough cleansing by means of dilute acid or other purifying means in
order to remove all greasy or unclean places which are always formed on it by the
machine or by the subsequent handling on the part of the workman during its
manufacture. In order to render possible a perfectly even impregnation of the
mantle fabric with suitable metallic oxide solutions, the first condition is that the
surface of the fabric must be absolutely clean. To obtain this condition, however,
obviously requires during manufacture an extremely exact and careful treatment
of the fabric employed.
The mantles at present employed have also the further drawback of an uneven
distribution of material on their periphery which causes the radiation of light
therefrom to be visibly of unequal strength. The reason of this is that the said
mantles are cut from a flat surface, are then impregnated with suitable metallic.
oxide solutions, and this piece of fabric is then sewn together on its longitudinal
edges, so that there is naturally at the seam a double layer of material, that is to
say, it is thicker there than at the other parts. Even if the mantle be made
directly of a tubular woven fabric, it shows at two opposite places a greater
thickness of material, because this tubular fabric, after impregnation with suitable
metallic oxide solutions, is pressed between rollers or other suitable devices, and
consequently there is produced a flattening and stronger compression not only at
the two longitudinal edges, or overlapping parts, but also at several other places
where the fabric in question will crease or lie in folds so that there also a flattening
aud stronger compression of the fibrous material will take place.
Thus all these mantles in consequence of the unequal distribution of their
material can never radiate an equally strong light.
This invention has for its object to remove the above drawbacks and to produce
incandescent mantles with a faultlessly even distribution of their material. For
this purpose threads or yarns of suitable material and strength, immediately after
their manufacture are washed and bleached and then saturated with a solution of
thorium oxide or of one or more other suitable metallic oxides, and then knitted
or eventually also woven into a tubular or other suitable form without its being
necessary to again wash or clean the material and without fear of the fibres
becoming more closely accumulated at certain places or of an unequal saturation
being caused with the impregnating substances as was hitherto the case.
If pieces
of suitable length be then cut off from shapes made in this way, incandescent
mantles are immediately produced for each kind of incandescent burner.
As has been found in practice and as will be apparent to any practical person,
such mantles show a complete even distribution of the material on their periphery,
and, in consequence of this, they give off an entirely even light, and should the
thread actually have received here and there a small spot of grease or other

page_text: impurity, such spots will show less bad places in the fabric when formed into an
incandescent mantle, because, in the first place, a small and imperfectly impregnated
part of the thread will be less observable in the shaped form, and, secondly,
because such a place in the thread may be always covered over by an adjacent well
impregnated part in the shape or form in such a way that it cannot at all project
out of the same. The entire incandescent mantle appears therefore as a completely
even one.
It is otherwise, however, if a greasy or impure place is contained in the fabric
by the old method as these must, when serving for forming the incandescent mantle,
be further treated. In this case such an unclean spot would always have a
deleterious effect and will never remain without influence on the production of a
good article.
The incandescent mantles made by the process hereinbefore described show, on
the other hand, an absolutely even distribution on their periphery, both of fibrous
material and also of the impregnating substance and consequently give off a
thoroughly even incandescent light.
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―
An improved process of manufacturing incandescent mantles for incandescent
burners, consisting in impregnating thread like material of suitable thickness with
a solution of a suitable metallic oxide, and more particularly thorium oxide with
eventually the addition of other suitable metallic oxides, and in afterwards knitting
or weaving same to form tubular or other shaped incandescent mantles, whereby
mantles are produced having a perfectly even distribution of material on their
péripheries substantially as hereinbefore described.
Dated this 8th day of September 1896.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.