Improvements in Washing Photographic Plates and Prints, and in Apparatus therefor.
Year: 1896

page_text: Date of Application, 2nd July, 1896
Complete Specification Left, 18th Nov., 1896-Accepted, 2nd Jan., 1897
PROVISIONAL SPECIFICATION.
Improvements in Washing Photographic Plates and Prints, and in
Apparatus therefor.
I, AUGUSTUS LEHMANN of 42 Narcissus Road, West Hampstead, London N.W.,
Commercial Agent, do hereby declare the nature of this invention to be as
follows:-
Most of the photographic plate and paper print washers in use are based on a
strong current of water being passed through a tank in which the plates or prints
are placed. This current plays against the plates or chases the paper prints abou
the tank. Such rigorous treatment frequently results in pinholes in the film of the
plates, or friction, doubling up or adhering together of the paper prints, thereby
injuring the delicate coating of albumen, gelatine or other substances. The final
washing to remove the fixing salt or hyposulphite of sodium is the most trying to
the film or coating and in the ordinary course necessitates a considerable length of
time. On account of the rotary current of water, even with a constant in and out
flow, the fixing salt as it dissolves from the film gets incorporated with the body of
the water and diffused all over the tank, which prevents the film from getting
quickly freed from the fixing agent.
:
It is well known to photographers that prolonged or violent washing. removes
much of the colorific matter of the prints and that traces of hyposulphite of sodium
left in the plates or prints impair their durability.
In order to obviate the disadvantages pointed out above I proceed as follows:
I construct a tank of zinc or other suitable material, in any shape, but preferably
upright cylindrical, with an outlet or gap at the bottom, and having a false bottom
of perforated material. In this tank I place on the false bottom a nest or set of
specially constructed carriers on which the plates or prints rest.
These carriers may be made of any material which cannot injure the photographs
by chemical action. For cheapness and convenience I recommend zinc. The
carriers consist of two closely perforated plates a little larger than the photographic
plates or prints they are to carry and are joined at one end in such manner that
they form an angle or roof.
I prefer to join them at the broad side in a sharp angle of about 75 degrees.
Each of the two flat sides of this carrier has a ledge at the base and at the sides to
prevent the photographic plates from slipping downward or sideways. Underneath
the perforated plates and a little away from the ends are strips of the width
of to 1 inch or more, placed in such manner that, they form a right angle.to the
plane of the plates. The distance of the strips from the edges must be just
sufficient to enable me to place one carrier on the top of another with the strips of
the upper one resting closely inside the side ledges of the lower one and allowing
a clear space between the surfaces of the two carriers.
Each carrier holds two plates or pictures resting obliquely to each other and a
convenient number of carriers can in this way be piled up. In the case of
photographic plates it is best to have the carriers large enough to enable the plates
to rest clear of the said strips of the carrier above them in order not to injure the
films, the weight of the plates being sufficient to keep them in position; but in the
case of paper prints the said strips must be so arranged as to rest on the edges of
the paper, thereby holding it down and preventing its slipping.
The plates or paper prints are placed face upwards.
14

page_text: If it is desired to lift the piled up carriers all together one or two rods each end
can be passed through loops fixed for that purpose to the carriers. The rods may
either be fixed to the bottom carrier, which is the best plan, or have a button, or
cross piece, or hook at the lower end underneath the loops of the lowest carrier;
the whole set can then be lifted by the.rods.
In order to give free access to the water from all sides of the carriers
I perforate the said strips, or instead of strips I use a number of separate small
pieces fixed in the place of the said strips.
Though this angular shape of the carrier is the best one for plates I may,
especially in the case of paper prints, use carriers of saddle or semi circular shape,
or rounded or flattened at the top and carrying only one photograph laid across
.instead of two. Further, the carriers need not be perforated but might be plain or
grooved; however perforated plates answer best.
The whole carrier may be cast in one piece or produced in any other way,
so long as the form with regard to its special features is maintained.
The ledges at the bottom may be left out where only paper prints are used.
The tank is filled with water and the carriers holding the plates or photographs
are placed into it. If there is room more than one set can go in at the same time.
The higher the tank is the better the solving action of the water on account of the
greater pressure.
Where a constant supply of water is obtainable the tap at the bottom is then
turned on and an equal quantity of water to that drawing off is allowed to pass in
from the top spreading over a plain or perforated plate fixed a little way
underneath the influx to break its force. The apparatus requires no further
attention until the plates or pictures are ready to be taken out...
The body of the water in its gentle downward course, assisted by its own pressure,
acts on the pores and surfaces of all the plates and prints simultaneously, solving
and carrying down the fixing agents without bringing the solution in contact with
the lower plates or prints to any appreciable extent.
.
The sloping position of the plates or prints insures a speedy fall of the hypo-
sulphite of s dium which is known to be heavier than water, and by the continuous
influx of fresh water from the top the photographs get quickly washed while they
remain at rest and cannot get injured.
Where there is no constant supply the water must be repeatedly drawn off from
the tank and renewed, taking care that no stream of water is brought into violent
contact with the plates or prints. The fixing salt solved out of the coating of the
plates or paper collects below the false bottom of the tank.
For large tanks the carriers may have surfaces large enough to hold a number
of plates side by side, and in the case of paper prints corresponding strips or rests
can be arranged to hold the prints down.at the edges and give support to the larger
-surfaces of the carriers.
A further improvement by which the fixing agent can be thoroughly and much
quicker removed is the following:
The tank as before.described is filled with water and the carriers charged with
plates or pictures are placed into it; the tank is then hermetically closed by tightly
screwing on a lid provided with a thick india rubber washer, in the manner of a
screw stopper, if the tank is narrow and cylindrical. The lid may also be fixed by
bolts, clamps, or any other couvenient device.
A small pump is connected with the lid or side of. the tauk, by which water can
be injected. With a few strokes of the pump a certain amount of pressure is
obtained on the body of the water, forcing it into the pores of the films aud the
paper, thereby expelling any tiny air bubbles and' dissolving the fixing solution
contained in the pores and on the surfaces through forcible incorporation with that
solution. :
The pressure is left on for a short time to allow the dislodged hyposulphite of
soda to collect underneath the false bottom; the tap is then turned on and a
quantity of the water blown off carrying the dissolved fixing salt with it.

page_text: This operation is repeated several times. Each time the pressure is released by
blowing off water the pores in the films or paper partly or wholely close again by
contraction, thereby forcing out water charged with fixing solution.
pressure is equal from all sides the plates or paper remain at perfect rest on the
carriers.
Experiments have shown that the pressure does not injure the films which resume
their natural gloss when dry.
I have also obtained good results by pumping air into the tank filled with water,
and for my experiments I have used an ordinary bicycle tyre pump to a small tank
holding 24 half plate photographs on the carriers.
The tyre valve was fixed in the lid and the pump screwed on to it in the same
manner as is done for inflating a tyre.
The only disadvantage with air pumping is that no fresh water can be injected to
replace that blown off from time to time, but fresh water might be let in through a
suitable opening with a screw stopper in the lid when the pressure is off, or through
a tube provided with a stop cock in the lid or side of the tank.
In order to regulate the pressure to a nicety attach a pressure guage to the
tank, but where no pressure guage is used the pressure may be judged by the
number of strokes of the pump or from the force of the water on turning on
the tap. A water guage may also be attached to the tank.
. Another means of estimating the pressure is a safety valve fixed in a convenient
place, as for instance the lid.
Deshid i f. 1900
Improvements in Washing Photographic Plates and Prints, and in.
Apparatus therefor.
I, AUGUSTUS LEHMANN of 42 Narcissus Road, West Hampstead, London N. W.,
Commercial Agent 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 :-
Most of the photographic plate and paper print washers in use are based on a
strong current of water being passed through a tank in which the plates or prints
are placed. This current plays against the plates or chases the paper prints about
the tank.
Such rigorous treatment frequently results in pinholes in the film of the plates,
or friction, doubling up, or adhering together of the paper prints, thereby injuring
the delicate coating of albumen, gelatine or other substances. The final washing to
remove the fixing salt or hyposulphite of sodium is the most trying to the film or
couting, and in the ordinary course necessitates a considerable length of time. On
account of the rotary current of water, even with a constant in and out flow, the
fixing salt as it dissolves from the film gets incorporated with the body of the water
and diffused all over the tank, which prevents the films from getting quickly freed
from the fixing agent.
It is well known to photographers that prolonged or violent washing removes
much of the colorific matter of the prints, and that traces of hyposulphite of sodium
left in the plates or prints impair their durability.
In order to obviate the disadvantages pointed out above I proceed as follows:
I construct a tank of zinc or other suitable material in any shape, but preferably
upright cylindrical, with an outlet or tap at the bottom and having a false bottom
of perforated material. It is of importance that the bottom should be concave
with a hole in the centre by which the water is passed through a tube to the

page_text: tap. In this tank 1 place on the false bottom a nest or set of specially constructed
carriers, on which the plates or prints rest. These carriers may be made of any
material which does not injure the photographs by chemical action. For cheapness
and convenience I recommend zinc. The carriers consist of two closely perforated
plates a little larger than the photographic plates and of the same size as the
prints they are to carry, and are joined at one end in such manner that they form
an angle or roof. I prefer to join them at the broad side in a sharp angle of about
75 degrees. Each of the two flat sides of this carrier has a ledge at the base and
at the sides to prevent the photographic plates or prints from slipping downward
or sideways.
Underneath the perforated plates and a little away from the ends are thin strips
of the width of inch or more, placed in such manner that they form a right
angle to the plates. The distance of the strips from the edges must be just
sufficient to enable me to place one carrier on the top of another with the strips of
the upper one resting closely inside the side ledges of the lower one, and allowing
a clear space between the surfaces of the upper and lower carrier.
Each carrier holds two plates or pictures resting obliquely to each other,
and a convenient number of carriers can in this manner be piled up.
In the case
of photographic plates it is best to have the carriers large enough to enable the
plates to rest clear of the said strips of the carrier above them, in order not to
injure the films, the weight of 'the plates being sufficient to keep them in position ;
but in the case of paper prints the said strips must be so arranged as to rest on
the edges of the paper, thereby holding it down and preventing its slipping.
The plates or paper prints are always placed face upwards.
If it is desired to lift the piled up carriers all together one or two rods each end
can be passed through loops fixed for that purpose to the carriers.
The rods may be either fixed to the bottom carrier, which is the best plan, or
have a button, or cross piece, or hook at the lower end underneath the loops of the
lowest carrier; the whole set can than be lifted by the rods.
In order to give free access to the water from all sides of the carriers I perforate
the said strips, or instead of strips I use a number of separate small pieces, or
I make the edge of these strips toothed.
It is also advisable to place a solid plate of ziue or other material a little way
underneath the perforated plates on which the pictures rest, in order to prevent
the water from the back of the prints coming in contact with the prints
underneath.
I may here mention that aluminium is a very good material for the manufacture
of the carriers and the tanks.
Though this angular shape of the carrier is the best one for plates I may,
especially in the case of paper prints use carriers of saddle or semi-circular shape,
or rounded or flattened at the top and carrying only one picture instead of two.
Further, the carriers need not be perforated but might be plain or grooved;
however, perforated plates answer best.
The whole carrier may be cast in one or more pieces, or produced in any other
way so long as the form with regard to its special features is maintained. The
ledges at the base may be left out where only paper prints are used.
The tank is filled with water and the carriers holding the plates or photographs
are placed into it. If there is room more than one set can go in at the same time.
The higher the tank is the better the solving action of the water on account of
the greater pressure with constantly moving water.
Where a constant supply is obtainable the tap at the bottom is then turned on
and an equal quantity of water to that drawing off is allowed to pass in from the
top, spreading over a plain or perforated plate fixed a little way underneath the
influx to break its force. If a tube is connected with the supply tap the water
may be led against the inner surface at the top of the tank.
The apparatus requires no further attention until the plates or pictures are
ready to be taker our.

page_text: The body of the water in its gentle downward course, assisted by its own
pressure, acts on the pores and surfaces of all the plates and prints simultaneously,
solving and carrying down the fixing, agents without bringing the solution in
contact with the lower plates or prints to any appreciable extent. The sloping
position of the plates or prints insures a speedy fall of the hyposulphite of sodium
or hyposulphite of sodium silver which is known to be heavier than water, and
by the continuous influx of fresh water from the top the photographs get quickly
washed while they remain at rest and cannot get injured.
Where there is no constant supply the water must be repeatedly drawn off from
the tank and renewed, taking care that no stream of water is brought in contact
with the plates or prints. The fixing salt solved out of the films and paper collects
below the false bottom.
A further improvement by which the fixing agent can be thoroughly and much
quicker removed is the following:
The tank as before described is filled with water and the carriers charged with
plates or prints are placed into it.
The tank is then hermetically closed by tightly screwing on a lid provided with
a thick india rubber washer, in the manner of a screw stopper if the tank is
narrow and cylindrical..
The lid may also be fixed by bolts, clamps, or by any other convenient device.
A good plan is to connect the lid with the tank by means of a hinge and fasten the
lid down on the opposite side with a screw or clamp.
A small pump is connected with the lid or side of the tank, by which water can
be injected. With a few strokes of the pump a certain amount of pressure is
obtained on the body of the water, forcing it into the pores of the films and of
the paper, thereby expelling any tiny air bubbles and dissolving the fixing solution
contained in the pores and on the surfaces through forcible incorporation with that
solution. The pressure is left on for a minute or less and the tap below turned on
to blow off some of the water and remove the pressure. The tap is then closed
and the operation repeated several times. After this a vent hole in the lid is
opened and the tank emptied through the tap below. Fresh water is then let in
from the top along the side of the tank and in order to do this without loss of
time I place a piece of metal tubing, provided with a stop cock, through the lid.
This tube is connected by means of an india rubber hose with the supply tap
or cystern.
The operation of applying and releasing pressure is then renewed and the tank
emptied and refilled several times.
All this occupies a very short time the length of which depends on the quantity
of fixing solution absorbed by the paper or films.
To find out whether every trace of fixing solution bas been removed the usual
tests can be applied to the water blown off.
Finally I open the bottom tap, the supply tap and stop cock mentioned above,
and the vent hole, and pass a constant course of water through the apparatus for a
few minutes without pressure.
Every time the pressure is released by blowing off water the pores in the films
and paper partly or wholly close again by contraction, thereby forcing out water
charged with fixing solution. As the pressure is equal from all sides the plates or
paper prints remain at perfect rest on the carriers.
A pressure of from two to five pounds to the square inch answers its purpose,
but I have in my experiments applied from 15 to 20 pounds without any injury
whatever to the delicate film of gelatine emulsion paper.
After drying the pictures retain their usual gloss.
I have also obtained good results by pumping air into the tank filled with water
and for my experiments I have used an ordinary bicycle tyre inflating pump to a
small tank holding 24 half-plate photographs on the carriers. The tyre-valve was
fixed in the lid and the pump screwed on to it in the same manner as is done for
inflating a tyre. The only disadvantage with air pumping is that no fresh water

page_text: can be injected to replace that blown off from time to time, but fresh water might
be let in through the stop cock in the lid when the pressure is off.
In order to regulate the pressure to a nicety I attach a pressure guage to the
tänk, or a safety valve would answer the same purpose.
Where neither is used
the pressure may be judged, after a little practice, by the number of strokes from
the pump, or from the force of the water blowing off on trying the tap. A water
guage could also be attached to the tank.
Instead of pumping air or water into the tank I can apply pressure by fixing on
the lid or other part of the apparatus a metal barrel in which a tightly packed
piston can be moved up and down by means of a rod having a handle at the end.
The mouth piece of the barrel reaches into the tank and the other end is closed
by a screw cap with a hole through which the piston rod passes. The whole is
similar to au ordinary hand syringe. The piston is drawn quite back, the tank
filled right up to the top with water, the stop cock and veut hole closed, and
pressure is brought to bear on the body of the water by pushing the piston down.
The same result could be obtained by a forcing cup, made of india rubber with a
handle to it, but all such methods are not satisfactory as they necessitate opening
of the stop cock after each blowing off, in order to admit fresh water. The blowing
off after each application of pressure is essential in order to move the whole body
of water in the tank and for bringing fresh particles of water in contact with the
plates or prints.
For large tanks the carriers may have surfaces large enough to hold a number
of plates side by side, and in the case of paper prints corresponding strips or rests
can be arranged to hold the prints down at the edges in the manner described for
carriers of two pictures, and to act as support for the larger surfaces of the
carriers.
EXPLANATION OF DRAWINGS:
Fig. 1 is the front elevation of the carrier, showing the perforated plate A and
the side ledges B. B.
Fig. 2 is the side elevation of the carrier, showing the angle formed by the two
plates, the side ledges B. B. and the strips C. C.
་
Fig. 3 is a lateral section of the front or back of the carrier, showing the
relative position of the perforated plate A to the solid lower plate D, with side
ledges B. B. and the strips C C.
Fig. 4 is a perspective view of the carrier, showing front, side, part of back A
and the bottom ledge Bb.
Fig. 5 showes the cylindrical washing apparatus with the side broken open to
disclose the side view of a set of nine carriers E E, resting on the false bottom F,
also the concave bottom G and in dotted lines the outlet tube leading to the
draw-off tap H. The tap I above the apparatus shows the position of the inlet of
water.
Fig. 6 is the outside view of the apparatus for washing with pressure. K is the
pressure pump attached to the side of the apparatus, Lan india rubber hose for
drawing water from a cystern M for feeding the pump. N is the lid connected
with the tank by means of a hinge O and clamp P. Q'is a pressure guage, R the
vent hole with screw cap, S the stop cock of the water supply, T an india rubber
hose connecting the stop cock with the water supply and H is the draw-off tap.
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:
1. The carriers for holding photographic plates or paper prints, substantially as
herein described.
2. The upright cylindrical washing apparatus for holding one or more sets of
carriers and allowing space above the sets of carriers with the object of exercising
an extra water pressure by gravity, substantially as herein described.

page_text: 3. The application of pressure upon the body of water contained in any
hermetically closed tank or vessel in which photographic prints or plates are
placed, with the object of removing the fixing solution, or its silver combination,.
from the pores and surfaces of the paper prints or the coating of plates or films.
4. The cylindrical apparatus for washing photographic plates or prints, with
hermetically closing lid, and connected with water or air pressure, substantially as
herein described.
Dated this Eighteenth day of November 1896
A. LEHMANN.