Process for Stiffening or Strengthening Flexible or Fragile Objects in Order to Facilitate their Manipulation.
Year: 1893

page_text: Date of Application, 27th Feb., 1893-Accepted, 24th June, 1893
COMPLETE STEIFICATION.
Process for Stiffening or Strengthening Flexible or Fragile Objects
in Order to Facilitate their Manipulation.
I, JOHANN BÖHM, Architect, of Aachenstrasse, Cologne, in the German Empire,
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 :-
This invention has for its object, to strengthen or stiffen thin-walled flexible or
fragile objects, of metal, glass, porcelain, stoneware, wood or other suitable material,
in order to render them better fit for manipulation. Such objects may be flat, or
concave, or otherwise curved, and smooth or embossed or provided with designs in
relievo or intaglio.
The object to be strengthened, is provided on one side, that is the inner or
reverse side, with a layer consisting of a silicious binding substance (soluble glass),
sand and barium-white (barium sulphate), with or without the addition of a durable
colouring matter, which mixture is hereinafter called the " mass.
The proportions of these ingredients are preferably as follows:
Sand, 8 parts by volume; barium white, chalk or similar colouring matter
2 parts; waterglass (soluble glass) of 1.5 spec. gravity, 1-5 parts.
The soluble glass is preferably composed of or prepared from silica 16 parts,
potash 12 parts, charcoal powder 1 part, marble parts.
That side of the object which is to be strengthened, with the said "mass," is
first cleaned of dust, grease, polishing powder or other foreign bodies and coated
with a concentrated solution of soluble glass (alkali-silicate) or with a syrupy
mixture of "mass "and soluble glass; the mass, while still soft, is then applied to
this coating, so as to form a layer of suitable thickness, which may be done by
means of a spatula or knife, or by using moulds, so that the mass will already
adhere well to its base.
When the surface or outside of the mass has become dry and comparatively hard,
but before it has completely dried on the side which adheres to the object or
base (the access of air on this side being prevented by the object to be stiffened)
the whole is dipped into a concentrated solution of calcium chloride, care being
taken, that the "mass is at the top, which must also be the case, when the article
taken out of the bath is dried in the air.
The calcium chloride serves to produce a dense layer of calcium silicate between
the object and the mass, without diminishing the adhesion of the said mass upon
the object, but rather increasing it, because the mass gradually hardens as it
gets dry.
Instead of mixing the constituents of the said mass together before they are
applied to the object, the mixture may be made on the surface itself. In this case,
the surface, after having been cleaned, is coated with a syrupy mixture of soluble
glass with barium sulphate (with or without the addition of chemically inert
colouring matter), subsequently sand, or small particles of glass, slag, stone or
metal are strewed on.
When the coating has sufficiently dried, the object thus treated is placed in a
concentrated solution of calcium chloride.
The dipping, removal from the bath, and drying, are performed in the manner
described above. By this means a comparatively thin intermediate layer of the
mass has been produced on the object to be strengthened, the said layer serving as
a connecting link between the object and other gradually hardening masses, which
may be applied to this intermediate layer in a suitable manner, and adhere firmly

page_text: to the rough surface of the intermediate layer, so as to further strengthen the
object.
Instead of placing the mass on the object to be strengthened, when it is in a soft
condition, or producing it on the same, as described above, it may be previously
moulded from its constituents, and provided with holes or slots, that is to say, a
sieve-like, perforated, or porous body may be moulded from the mass, superficially
dried, and then cemented on to the object to be strengthened, by means of a
solution of soluble glass, with or without the addition of barium white or other
chemically inert powder. The whole is then dipped into a solution of calcium
chloride, the mass being placed at the top, which solution penetrates the apertures
or pores of the perforated mass and completes the hardening of the same and of
the cement layer.
The sand in the mass may be replaced by small particles of glass, stone, slag or
metal, and if the mass is not required to resist acids, the barium white may be
replaced by chalk.
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 ;-
The process for stiffening or strengthening flexible or fragile objects, which
consists in uniting one of its sides (the inner or reverse side) with a mass chiefly
consisting of soluble glass, sand and barium white, either by applying the said mass
in a soft condition, or by forming it in situ, or by first moulding the said mass into
a suitable form provided with pores or perforations, drying and then cementing it
to the object with soluble glass, the complete hardening of the mass and its intimate
connection with the object to be strengthened being effected by a bath of calcium
chloride, substantially as described and for the purpose specified.
Dated this 27th day of February 1893.
FAIRFAX & WETTER,
433, Strand, London, Agents.