Improvements in and relating to the Preparation of Non Metallic Porous Surfaces for Electro Metallurgic Deposits.
Year: 1888

page_text: Date of Application, 18th Apr., 1888
Complete Specification Left; 18th Dec., 1888
Complete Specification Accepted. 16th Feb, 188
:
Improvements in and relating to the Preparation of Non Metallic
Porous Surfaces for Electro Metallurgic Deposits.
I HUBERT STEINACH of the Polytechn. Verein Munich in the Empire of Germany
Engineer do hereby declare the nature of this invention to be as follows:-
=
The object of this invention is to prepare non metallic porous surfaces for receiving
electro metallurgic deposits in a more efficient and cheaper manner than heretofore.
To this end the improvements consist in employing purified tar and in the manner of
preparing the tar, of applying the same and of removing superfluous tar.
Suitable tar is used, preferably coal tar from gas factories and it is purified by
washing with dilute sulphuric acid and afterwards with water and subsequently with
an alcaline solution for instance diluted soda lye and again with water. The water
is drawn off and any remaining in the tar may if desired be expelled by moderate
heat.
The tar may also be purified by boiling.
The prepared tar is melted with about 10% of paraffin and the objects (for
instance plaster casts, statueties, papier maché and the like) are immersed therein
and drawn out coated with the tar, which hardens almost immediately thereon.
Since the coating of tar is apt to close up delicate moulding etc. and impair more or
less the outline of the object it may he reuioved where too thick by mechanical means
if desired. But I prefer to melt the tar upon the objects by means of a jet of steam
or of hot air or other suitable vapour so
down off the object and the outlines are kept
The objects are then removed to a drying
suitable time, when they will be suitable for
the usual manner.
the superfluous tar is permitted to run
clearly defined and sharp.
chamber and kept at a uniform heat for a
receiving electro metallurgic deposits in
HERBERT & Co.,
18, Buckingham Street, Strand,
Agents.

page_text: Porous Surfaces for Electro Metallurgic Deposits.
I HUBERT STEINACH of the Polytechn. Verein, Munich 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 object of this invention is to prepare non metallic porous surfaces for
receiving electro metallurgic deposits in a more efficient and cheaper manner than
heretofore.
To this end the improvements consist in employing purified tar and in the manner
of preparing the tar, of applying the same and of removing superfluour tar.
The tar is purified by washing with dilute sulphuric acid and afterwards with water
and subsequently with an alcaline solution for instance diluted soda lye and again with
water. The water is drawn off, and any remaining in the tar may, if desired be
expelled by moderate heat. The tar may also be purified by boiling.
The prepared tar is melted preferably with about 10% of paraffin and the objects
are immersed therein and drawn out coated with the tar.
Since the coating of tar is apt to close up delicate moulding and impair more or
less the outline of the object, it may be removed where too thick by mechanical means
if desired. But I prefer to melt the superfluous tar upon the objects by means of a
jet of steam or of hot air or other suitable vapour so that the superfluous tar is
permitted to run down off the object and the outlines are kept clearly defined and
sharp. The objects are then removed to a drying chamber and kept at a uniform heat
for a suitable time after which they will be suitable for receiving electro metallurgic
deposits in the usual manner.
In reducing this invention to practice I preferably proceed as follows:-
Any sort of tar may be used, the most suitable however is the coal tar of gas
factories. Such tar is in its original condition quite unsuitable for this purpose it
must therefore be subjected to a purification which has for its purpose to free the tar
of the ammonia water adherent thereto or combined or emulsified with the other
constituents of the tar and also of the greater part of the liquid and less volatile acids
and ethers (for instance carbolic acid, Kresol etc.).and bases such pyridin aniline etc.,
contained in the tar.
Thereby not only is the drying of the impregnated objects considerably facilitated
but also a subsequent sweating out matters from the tar and forming of soluble salts
in the acid bath is prevented.
If ordinary tar is employed, that is to say if the above substances are not removed
the latter form in the acid bath a black dirty liquid which renders the electro
metallurgic process absolutely impossible. The tar is preferably purified as follows:
Equal volumes of tar and of a 10% solution of sulphuric acid are roughly
stirred or agitated together and afterwards allowed to stand for a time, the acid liquid

page_text: swimming on the surface and containing the ammonia salts and the greater part of
the organic bases in the shape of sulphates, is poured off and the tar is washed by
agitation in frequent charges of water until the latter does not any longer show acid
reaction.
The tar treated as above described is then thoroughly agitated with the equal volume
of 10% solution of a soda salt or soda lye or other suitable alcali and after a certain
time of rest, the greenish brown fluorescent liquid containing the greater part of the
acid substances in the tar is drawn off, the tar is then washed with water until the
washing water shows no alcaline reaction. Then all the water is drawn off to the
last drop which is easly done. The tar now having the appearance of a perfectly
homogenous lustrous black mass is now ready to be used unless it is preferred to heat
it for some time to 100-120° Centigrade, for the purpose of removing any inherent
water and the volatile coal tar oils which are present in small quantities.
Since however for the subsequent impregnation of the objects the tar is warned
it appears superfluous to heat it expressly for the purpose mentioned above. The
tar purified as above described represents in the main a mixture of liquid and solid
hydrocarbons of the benzole series with burnt resins and finely divided carbon in
proportions varying within narrow limits.
Instead of preparing the tar in the above described manner it may also be boiled
for some longer time. With large quantities however the purification of the tar is
not so complete as by the process before described.
The prepared tar is heated to about 60° to 80° Centigrade and 10% paraffin
added for the purpose of rendering the mass more fluid and preventing it from
becoming thick as would otherwise be the case by continued use.
The non metallic porous bodies to be galvanized or plated such as plaster casts
statuettes articles of cement, papier maché and the like are dipped in this tar so that
they are completely permeated with the tar. This is only possible in a proper
manner by the addition of the paraffin.
As the impregnating liquid is immediately solidified on the object when taken out
the surfaces of the object can be freed from the superfluous tar by mechanical means
or solvents. Such a process however is troublesome and incomplete, and difficult to
carry out without injury to delicate parts of the objects.
1 therefore employ a novel process consisting in exposing the objects after they have
been taken out of the liquid to the blast of hot air or of dry steam or of any suitable
vapour. By the use of such blast, the superfluous tar is melted by the heat and
driven off by the power of the jet so that the object is left with perfectly pure
outlines.
The aforesaid addition of paraffin is also here important in this part of the process
since without it, the blowing off of the sulphurous tar would be considerably impeded.
The described operation is of course performed from above, downwards. After the
blowing off, the volatile hydrocarbons are removed by heating in a constant temperature
in a drying chamber in such a manner however that after heating, most of the less
volatile hydrocarbons remain in the pores of the object.
The penetration of water or acid into the object is prevented by the physical
properties of the resins and oils, the presence of finely divided carbon, in the tar the
retention of the less volatile particles of hydrocarbon and burnt resins by their partly
closing the pores and partly only coating the sides thereof. In the former case, the
penetration of water etc is impossible by the presence of the material, in the latter case
by capillary depression by reason of the coating on the sides.
The impregnation has been carried out properly after the above described process
if the places of fracture are similar in appearance to brown coal and become shining
and smooth by friction with a smooth instrument.
If the impregnated objects are intended to have a perfectly smooth surface for the
purpose of galvanizing they may be afterwards given a coat of lac solution of gutta
percha or such like.
The objects impregnated by the above process have the advantage of being
particularly unattackable by acid baths and impermeable to liquids.

page_text: Moreover the cost is considerably less than that of the processes generally.
employed.
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 1
claim is:
1. In the preparation of non metallic porous surfaces for electro metallurgic deposits,
the treatment of the same with tar purified from ammonia liquor acids, ethers and
bases or from the greater part thereof.
2. In the treatment of non metallic porous surfaces with purified tar for the purpose
set forth the combination with or addition to the tar of paraffin substantially as and for
the purpose described.
3. The herein described process of treating gas tar for the purpose set forth
consisting in agitating with dilute sulphuric acid washing with water agitating with
dilute soda lye or equivalent alcaline liquor and again washing in water.
4. The removal of the superfluous coating from objects prepared for electro metal-
lurgic deposits by means of a jet of hot air or steam or other heated vapour or spray
substantially in the manner described.
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