Improved Blast Process for Engraving.
Year: 1896

page_text: Date of Application, 14th Jan., 1896
'
Complete Specification Left, 11th Nov., 1896-Accepted, 12th Dec., 1896
[Communicated from abroad by THEODORE TRUCHELUT, of No. 6 Boulevard de
Strasbourg, Paris, Chemical Engineer.]
Improved Blast Process for Engraving.
1, HENRY HARINGTON LEIGH, Assoc. M. Inst. C.E., Fel. Ch. Inst. P.A.,
F.I. Inst., practising as Phillips and Leigh at 22 Southampton Buildings,
Chancery Lane, in the Administrative County of London, Engineer and Patent
Agent, do hereby declare the nature of this invention to be as follows:-
The process of engraving a friable substance such as glass or marble, by means
of a hard powder projected by an air blast against such portions of the surface as
are left exposed by a partial guard, is well knowu. But experience has shewn
that it is not applicable to relatively supple and pliant substances, the molecules of
which can be displaced by the rain of powder without being detached.
The object of the present invention is a process applicable to. all substances
indifferently. It is attained by the combination of the abrading action of the
blast propelled powder with the solvent action of a chemical.
The solvent action of the chemical is increased by the abrading action of the
blast propelled powder, especially by reason of the removal by the latter of any
oxide, precipitate or bubbles of gas, thereby maintaining a clean surface for the
chemical to attack.
Any convenient type of blower may be used in connection with the present
invention.
The powder, the chemical, as well as the degree of moisture of the mixture of
the two, must be selected and selected according to the nature of the substance to
be engraved. The selection of the powder is a simple matter: any of the materials
hitherto used in the well known sand blast process, such as sand, emery, or the like;
may be made use of. The selection of the chemical is merely a matter of common
chemical knowledge, once the natures of the powder and of the substance to be
engraved, are known. For instance, nitric acid will be chosen for zinc or copper;
aqua regia for steel, gold, silver or platinum; hydrochloric acid for aluminium,
horn, ivory or marble; potash for wood; and hydrofluoric acid for glass, slate,
granite or the like. Further, some substances are capable of both the abrading
and chemical actions, such as perchloride of iron upon copper. This double
property on their part brings them within the scope of the present invention.
Dated this 14th day of January 1896.
Improved Blast Process for Engraving.
1, HENRY HARINGTON LEIGH, Assoc. M. Inst. C.E., Fel. Ch. Inst. P.A.,
F.I. Inst., practising as Phillips and Leigh at 22 Southampton Buildings,
Chancery Lane, in the Administrative County of London, Engineer and Patent
Agent, do hereby declare the nature of this invention, and in what manner the
Price 8d3

page_text: same is to be performed, to be particularly described and ascertained in and by
the following statement :-
The process of engraving a friable substance such as glass or marble, by means
of a hard powder projected by an air blast against such portions of the surface as
are left exposed by'a partial guard, is well known. But experience has shewn
that it is not applicable to relatively supple and pliant substances, the molecules of
which can be displaced by the rain of powder without being detached.
The object of the present invention is a process applicable to all substances
indifferently. It is attained by the combination of the abrading action of the
blast propelled powder with the solvent action of a chemical.
The solvent action of the chemical is increased by the abrading action of the
blast propelled powder, especially by reason of the removal by the latter of any
oxide, precipitate or bubbles of gas, thereby maintaining a clean surface for the
chemical to attack.
Any convenient type of blower may be used in connection with the present
invention.
The accompanying figure is a vertical section of an apparatus suitable for the
purpose of the present invention and illustrating its action. A is a chamber
hermetically covered by the cover B and containing the powder and the chemical.
Compressed air is delivered through the pipe C and carries the chemical out of
the vessel A through the inclined pipe D. A current of compressed air, forced
through the pipe E in the direction indicated by the arrows, catches the mixture
of powder and chemical and blasts it against the surface F to be engraved.
The powder, the chemical, as well as the degree of moisture of the mixture of
the two, must be selected, and selected according to the nature of the substance to
be engraved. The selection of the powder is a simple matter: any of the
materials hitherto used in the well known sand blast process, such as sand, emery,
or the like; may be made use of. The selection of the chemical is merely a matter
of common chemical knowledge, once the natures of the powder and of the
substance to be engraved, are known. For instance, nitric acid will be chosen for
zinc or copper aqua regia for steel, gold, silver or platinum; hydrochloric acid
for aluminium, horn, ivory or marble; potash for wood; and hydrofluoric acid for
glass, slate, granite or the like. Further, some substances are capable of both the
abrading and chemical actions, such as perchloride of iron upon copper. This
double property on their part brings them within the scope of the present
invention:
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:-
The hereinbefore described process for engraving consisting of the projection by
blasting mixture of an abrading powder and a solvent chemical or of a simple or
a compound substance capable of acting mechanically by abrasion and chemically
by solution upon the surface to be engraved.
Dated this 11th day of November 1896.
HENRY H. LEIGH.