A NEW METHOD OF CONSTRUCTING TAN PITTS FOR TANNING OF HIDES AND SKINS, AND FOR STRIKING HIDES BY MACHINERY
Year: 1801

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GOTTLOB
FREDERIC LENZ, of Homerton, in the County of Middlesex, Tanner, send
grecting.
WHEREAS His most Excellent Majesty King George the Third did,
by His Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Eighteenth day of June,
in the forty-first year of His reign, give and grant unto me, the said Gottlob
Frederic Lenz, His especial licence, that I, the said Gottlob Frederic Lenz,
during the term of years therein mentioned, should and lawfully might use,
exercise, and vend, within the Kingdom of Great Britain, Principality
of Wales, and the Town of Berwick-upon-Tweed, my Invention of "A NEW
METHOD OF CONSTRUCTING TAN PITTS FOR TANNING OF HIDES AND SKINS, AND FOR
STRIKING HIDES BY MACHINERY;" in which said Letters Patent there is contained
a proviso obliging me, the said Gottlob Frederic Lenz, under my hand and
seal, to cause a particular description of the nature of my said Invention, and
in what manner the same is to be performed, to be inrolled in His Majesty's
High Court of Chancery within one calendar month after the date of the
said recited Letters Patent, as in and by the same, relation being thereunto
had, will more fully and at large appear.
NOW KNOW YE, that in compliance of the said proviso, I, the said
Gottlob Frederick Lenz, do hereby declare that my said Invention of A

page_text: New Method of Constructing Tan Pits for Tanning of Hides and Skins, and
for Striking Hides by Machinery, is described, ascertained, and used in
manner following, that is to say:-
The tan pits or tan vats in general ought to be made of wood, in
preference to brick-stone; first, because they hold the liquor better; secondly,
the lime which the construction of brick-stones requires weakens the liquor for
a considerable time, and to a considerable degree, before it is neutralized; and,
thirdly, it often happens that the frost in an hard winter raises the brick-stones,
which produces a loss of the liquor; whereas wooden vats, if once well made,
are never subject to be injured by the severity of the weather. Thus, in my
process, when the liquor, or, to use the technical term, the wooze, becomes of
more value than in the usual method of tanning, I would recommend the vatts
to be made of wood, and of the size of seven feet long, four and a half feet
wide, and six feet deep. They may be made of a smaller or larger size ;
however the above appears to me to be the most eligible.
The merits of my Invention consist of an improved method of heating the
wooze, which promotes the tannage, and, to obtain that end, you construct your
tan vats as above, and convey the heat into them in the following manner,
namely Arrange your vats in setts of three vatts, each sett with one or
more apertures at the bottom of each vatt for the purpose of conveying the
heat from the one into the other by means of small pipes, of either lead, wood,
or other materials, of about four inches more or less in diameter, which must
extend from one vat to another, and reach through the apertures; to prevent,
however, the communication of heat at any time, you place in the inside of your
vats before each pipe a spade or plug, which can be drawn up and down.
To heat the wooze, you place between two setts, or near two setts of vats, a
stove of any convenient size, of either cast iron or other materials, with a pipe,
for the conveyance of the smoak, of about one foot in length; join to it another
pipe which divides itself into two arms, one of which you direct through the
vat on the right hand, and the other through the vat on the left hand; both
pipes will thus be heated by the smoak, and will, of course, heat the wooze in
the vats through which they are directed. After the wooze in the first vat of
each sett is warm, you draw up your spades or plugs which lead to the second
vatts, and after the wooze in the latter is sufficiently warm, you open your
pipes of the third vats for conveying heat into them in like manner.
Striking hides has hitherto been an operation attended with no inconsider-
able expence, as well as loss of time, to obviate which you place two rollers
above each other, extend your hide upon a board of the size of the hide; let
it pass through your rollers forwards and backwards for several minutes;

page_text: the equal pressure of the rollers makes not only the leather firmer than in the
usual method of striking, but gives it also a finer appearance. The rollers
may be made either of wood, cast iron, or other materials, of eight feet in
length, and six inches more or less in diameter; they must be placed and
resemble in every respect Mr. Boulton's Copying Machine, and, consequently,
may be turned in the same manner with an handle by one person, while
another person introduces between the rollers the board with the hide upon it,
as already directed. As the hides are always thinner on the sides than on the
parts of the back and neck, the board on which they are to be extended must
be thicker on both side ends than what it is in the middle, and as the hides
differ in thickness, there are screws on each side of the rollers to raise and
lower them, according to the nature of the hide. By this operation one
hundred and fifty hides may be struck in one day with the assistance of two
common labourers, instead of employing two men at high wages, who would
require at least twenty days to perform the same work.
GENERAL INSTRUCTIONS FOR TANNING WITH WARM WOOZE, THE METHOD
PURSUED IN THIS INVENTION.
Preparation of the Wooze.-Take several leaches or tubs, place them near
each other or above each other, so that the liquor may be conveyed from the
one into the other with ease; fill each of them with an equal quantity of bark;
pour water on the bark in the first leach or tub; let it stand over it for twelve
hours, more or less, then convey the liquor on the bark in the second leach or
tub, and fill the first up again with water; after it has thus remained for some
hours, let the liquor out of the second leach or tub run into the third, the
liquor out of the first into the second, and pour water again on the first. I
would recommend that the liquor should be thus conveyed through six leaches
or tubs in the manner above described. When it comes out of the last it
will be very strong, and is then to be disposed of as will hereafter appear.
After the bark in the first. leach or tub has received water five or six times,
it will be nearly if not totally exhausted; then take it out and preserve it for
your handlers; then supply the first. leach or tub with fresh bark again, and
pour on it the liquor out of your last; thus, supposing you. have six leaches
or tubs, your first, will become the sixth, the second the first, and so on. This
operation you continue for the preparation of your wooze, as often as it is
wanted.
Tanning Crop Leather.-Treat the goods in washing, fleshing, unhairing,
and swelling, in the old accustomed manner. Afterwards put them into

page_text: handlers with a part of the bark which comes out of the leaches or tubs, and
fill them up with a weak wooze; in this situation they are to remain for about
two or three weeks, more or less, handling them, however, during that time once
.or twice every day; this operation takes the lime out which the hides may
.contain, and prepares them for the tannage. From the handlers steep your
hides in the your tan vat No. 1, in which the pipe of the stove is placed; fill it
up with a wooze of about two degrees of strength on the hydrometer for salts:;
let them remain there for about eight days. Prepare afterwards your vat
No. 2. with a wooze of about three degrees of strength; warm it, and shift
your hides from No. 1 into No. 2, and supply the former again with fresh
goods out of your handlers. After the expiration of eight or more days, fill
your vat No. 3 with a wooze of four degrees of strength; warm it, as before;
remove your goods from No. 2 into No. 3, those from No. 1 into No. 2, and
fill No. 1 up again with fresh goods out of your handlers. Let them stand in
this situation until the goods in No. 3 are completely tanned, and can be
taken out for drying. The wooze in No. 1 will then be very weak, and must
be taken out for the handlers. This process you continue for the tanning of
crop leather, only observe to keep your wooze in a regular gradation of
strength, such as above described.
Tanning Dressing Leather.-You flesh and unhair your goods in the usual
.manner; put them afterwards in your grainers, filled with pigeon or hen dung
and water, to separate them from the lime which they may contain; tako
them up and down frequently, and work them until they are perfectly
cleared of lime and grease. They are then to be put into an handler with
bark out of your leaches, and a weak wooze, wherein they are to be handled
once or twice every day for about six days, more or less, removing them
afterwards into a second handler filled with a small portion of fresh bark, and
a wooze of one degree in strength; in this situation they must also be handled
once every day for about six days; steep them afterwards in a warm wooze of
three degrees of strength, wherein they must remain until they are completely
tanned; get them, however, handled every day; the more the goods are
handled the more elasticity they will acquire.
In witness whereof, I, the said Gottlob Frederic Lenz, have hereunto
set my hand and seal, the Thirteenth day of July, in the year of
our Lord One thousand eight hundred and one.
G. F. LENZ. (L.S.)

page_text: AND BE IT REMEMBERED, that on the same Thirteenth day of July,
in the year above mentioned, the aforesaid Gottlob Frederic Lenz came
before our Lord the King in His Chancery, and acknowledged the Speci-
fication aforesaid, and all and every thing therein contained, in form above
written. And also the Specification aforesaid was stamped according to the
tenor of the Statute in that case made and provided.
Inrolled the Fourteenth day of July, in the year above written.