RESTORING THE SURFACE OF A MIEDER ORIGINAL STATED
Year: 1863

page_text: LETTERS PATENT to Max Pettenkofer, Professor of Chemistry in the
University of Munich, Member of the Royal Academy of Science in
Munich (Bavaria), for the Invention of "RESTORING THE SURFACE OF
A
MIEDER ORIGINAL STATED'
"
Sealed the 12th April 1864, and dated the 20th October 1863.
PROVISIONAL SPECIFICATION left by the said Max Pettenkofer at the
Office of the Commissioners of Patents, with his Petition, on the
20th October 1863.
I, MAX PETTENKOFER, Professor of Chemistry in the University of Munich,
Member of the Royal Academy of Science in Munich (Bavaria), do hereby
declare the nature of the said Invention for "RESTORING THE SURFACE OF
PICTURES IN OIL WITHOUT ANY DANGER TO THEIR ORIGINAL STATE," to be as
follows:-
Observation and experiment show that the changed appearance we notice
in varnished pictures in oil after the lapse of some years is caused in most
cases by physical and not by chemical influences. Time causes in the said
objects the discontinuance of molecular cohesion. The process begins on the
surface with microscopical fissures in the varnish, and penetrates by and by

page_text: through the different coats of colour to the very foundation. The surface and
the body of such a picture becomes in the course of time intimately mixed
with air, and reflects light like powdered glass, or looses its transparency like
oil intimately mixed with water or air. The best method of rejoining the
separated molecules without any danger or damage to the original is the
following The picture is exposed to an atmosphere saturated with vapour of
alcohol at the ordinary temperature (without applying heat). The resinous
particles of the picture absorb alcohol from that atmosphere until they are
saturated and not more. By this process the different separated molecules re-
acquire cohesion with each other, and the optical effect of the original is restored
solely by self-action, the picture not getting touched at all; and this principle
of self-action, differing so essentially from all former known methods of
restoring paintings in oils, forms the subject of the Patent applied for. The
very small quantity of alcohol absorbed evaporates very soon when exposed to
the ordinary atmosphere, and the surface of the picture remains clear as long
as a newly varnished surface.
lid is
The most serviceable and convenient apparatus for the above purpose
consists of some wooden case of the size required, about three inches deep, and
lined inside with some metal, for instance zinc, with exception of the lid, to
which the picture or pictures to be restored are fastened by screws in the usual
manner as in an ordinary packing case; alcohol is then poured in the metal
lined bottom of the box or case, and the shut, suspending thus the
pictures face downwards over the alcohol. From time to time the lid is
opened in order to watch the progress of the restoration and to take out those
paintings that have absorbed sufficient vapour. The apparatus must of course
be varied, in case a picture could not well be removed from its place. Then a
case, but without lid and metal lining, is required a little larger than the
painting, the bottom of which is inside covered with some absorbing stuff, for
instance, flannel, or the like, which is slightly sprinkled over, and thus but just
moistened with alcohol, and then the case is fastened over the painting so as
to cover it completely. Of course a variety of appliances might be contrived,
but they need not be described, since the newly discovered principle of self-
action by vapours only is the subject to be patented, and the two apparatus
described are quite sufficient to elucidate it. Thus, in the same manner other
substances can be used instead of alcohol, for instance, wood naphta, ether,
sulphuric and other ethers, turpentine, petroleum, benzine, and the various
attars, and in special cases higher and lower temperature is to be employed,
but all that is but subordinate and secondary to the principle of self-action by

page_text: absorption of vapour, the subject of this new and important discovery and of
the present Patent.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Max Pettenkofer in the Great Seal Patent Office on the
13th April 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MAX
PETTENKOFER, Professor of Chemistry in the University of Munich, Member
of the Royal Academy of Science in Munich (Bavaria), send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of October, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-seventh year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Max Pettenkofer, Her special licence that I, the said Max Pettenkofer,
my executors, administrators, and assigns, or such others as I, the said Max
Pettenkofer, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and all times thereafter during
the term therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "RESTORING THE SURFACE OF
PICTURES IN OIL WITHOUT ANY DANGER TO THEIR ORIGINAL STATE," upon the
condition (amongst others) that I, the said Max Pettenkofer, my executors
or administrators, by an instrument in writing under my, or their, or one
of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Max Pettenkofer, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, that is to say :-
Observation and experiment show that the changed appearance we notice
in varnished pictures in oil after the lapse of some years is caused in most
cases by physical and not chemical influences. Time causes in the said objects
the discontinuance of molecular cohesion. The process begins on the surface

page_text: with microscopical fissures in the varnish, and penetrates by and by through
the different coats of colours to the very foundation. The surface and body of
such a picture becomes in the course of time intimately mixed with air, and
reflects light like powdered glass, or looses its transparency like oil intimately
mixed with water or air. The best method of rejoining the separated
molecules without any danger or damage to the original is the following:-
The picture is exposed to an atmosphere saturated with vapour of alcohol at
the ordinary temperature (without applying heat). The resinous particles of
the picture absorb alcohol from that atmosphere until they are saturated and
not more.. By this process the different separated molecules.reacquire
cohesion with each other, and the optical effect of the original is restored
solely by self-action, the picture not getting touched at all; and this principle
of self-acting restoration by means of vapour alone, differing so essentially from
all former known methods of restoring paintings in oil, forms the subject of
the Patent applied for. The very small quantity of alcohol absorbed evaporates
very soon when exposed to the ordinary atmosphere, and the surface of the
picture remains clear as long as a newly varnished surface.
'
The most serviceable and convenient apparatus. for the above purpose is
some wooden case of the size required, about 3 inches deep, lined inside with
some metal, for instance zinc, with exception of the lid, to which the pictures
or the pictures to be restored are fastened by screws in the usual manner, as in
ordinary packing cases. Alcohol is then poured in the metal lined bottom of the
box or case, and the lid is shut, thus suspending the pictures face downwards
over the alcohol. From time to time the lid is opened in order to watch the
progress of the restoration, and to take out those paintings that have absorbed
sufficient vapour. The apparatus must of course be varied in case a painting
could not well be removed from its place, then a case, but without lid and
metal lining, is required a little larger than the painting, the bottom of which
is inside covered with some absorbing stuff, for instance, flannel, or the like,
which is slightly sprinkled over, and thus only just moistened with alcohol,
and then the case is fastened over the painting, so as to cover it completely.
Of course a variety of appliances might be contrived, but they need not be
described, since the newly discovered principle of self-action by vapours.only is
the subject to be patented, and the two apparatus described are quite sufficient
to elucidate it. Thus, in the same manner other substances can. be. used
instead of alcohol, for instance, wood naphta, ether, sulphuric and other ethers,
turpentine, petroleum, benzine, and the various ottos, and in special cases
higher and lower temperature is to be employed, but all that is but secondary

page_text: and subordinate to the principle of self-action by absorption of vapour, the
subject of this new and important discovery and the present Patent.
In witness whereof, I, the said Max Pettenkofer, have hereunto set
my hand and seal, this Ninth day of April, in the year of our Lord
One thousand eight hundred and sixty-four.
Munich (Bavaria).
Signed, sealed, and declared before
me, this Ninth day of April 1864,
Munich, April 9, 1864,
P. LE POER TRENCH,
3rd Secretary to H. M.'s Legation.