Associated with the use of iodine and bromine is an art which every
intelligent boy may practice, if he will attend to the following
precise details kindly furnished by an experienced photographer.
HOW TO MAKE THE NEGATIVE ON GLASS, USING COLLODION BROMOIODIZED FOR
IRON DEVELOPMENT.
1. The edges of the glass should be ground all round, also slightly
on the surface of the edges. This prevents contraction of the film,
enabling it to resist the action of a heavy stream of water. Mark
one side in the corner with a diamond, and upon this side bestow the
greatest care.
2. _To clean the glass, if new._--Make a mixture of spirits of wine
and solution of ammonia, equal parts; render it as thick as cream with
tripoli; with a piece of cotton-wool kept for this purpose rub a small
quantity over that side marked as described, wash well under a tap of
water, and wipe dry with a piece of old linen, washed without soap, and
kept scrupulously clean for this purpose. Plates should not, however,
be cleaned in the operating room with the above mixture; the vapor of
ammonia might prove injurious to the chemicals.
3. Now polish with an old white silk handkerchief. If this latter
precaution be not taken, small particles of linen will be left upon the
plate: these are perhaps only seen when draining off the collodion;
they form nuclei and eddies, checking the collodion in its course.
Some of these minute fibers are washed off, and contaminate the next
picture. To all lovers of clean pictures our advice therefore is,
having well dried the plate with old linen, lay it, clean side upwards,
upon a few sheets of common glazed demy paper (not blotting), and
rub it hard with the silk until sensibly warm; this has the double
advantage of dispersing fibers and moisture, for all glass plates are
slightly in a hygrometric condition. Double the silk rubber up to form
a pad, and with this the glass must be firmly dusted down just before
pouring on the collodion, which will then run most evenly; if the
coated plate is now viewed by transmitted light, not a speck or blemish
will be seen upon it. When a plate cleaned as above described is
breathed upon, the moisture does not evaporate slowly, but _flies off_.
Do not be afraid of putting the glass into an electrical condition with
the silk rubber; on this account objections have been raised to the use
of silk; practically, however, I find it a most valuable auxiliary in
this starting-point of the process, the perfect manipulation of which
makes an important difference in the value of the finished picture.
What can be more inartistic and annoying to an educated eye than spots,
patches, stars, and sky-rockets, the forms and shapes of which rival,
in numberless variety, a display of fireworks? Let us not, therefore,
be contented with pictures, however good in other respects, presenting
these deformities--so many blots on the photographic escutcheon.
_To clean a glass after having used it, when not varnished._--Wash off
the collodion film with water, then clean the marked side with plain
tripoli and water, and dry as above.
_To coat the plate._--First remove all the particles of dried collodion
from the mouth of the bottle. Now pour upon the center of the cleaned
glass as much collodion as it will hold. Do not perform this operation
hurriedly, take time, and systematically incline the plate in such a
manner that the collodion may run into each corner in succession; when
perfectly covered, pour off gently the excess into the bottle at one of
the corners nearest to you; with observation and practice dexterity is
easily acquired. There are many ways of coating the plate; each person
will adopt that which practice teaches him is best. The pneumatic
plate-holder is a convenient little instrument to use for holding the
plate whilst pouring on the collodion; it may be used for both small
and large plates.
Keep the corner of the glass plate in contact with the neck of the
bottle whilst pouring off the collodion; otherwise the film will be
wavy in places.
4. As soon as the collodion ceases to run, plunge the prepared glass
gently, without stopping, into the nitrate of silver bath, which is
prepared as follows: Into a 20-oz. stoppered bottle put nitrate of
silver, 1-1/4 ozs.; distilled water, 4 ozs.; dissolve. To this solution
add iodide of potassium, 4 grs., dissolved in one drachm of distilled
water. Mix these two solutions; the precipitate (iodide of silver)
thus formed is by shaking entirely dissolved. Add 16 ozs. of distilled
water, when the excess of iodide of silver is again thrown down, but
in such a finely divided state as to render the saturation of the bath
with iodide of silver perfect. Now drop in sufficient of the oxide of
silver to turn the turbid yellow solution a dirty brown color; so long
as this effect is produced the quantity of oxide of silver, however
much in excess, is of no consequence; shake the bottle well for ten
minutes or so at intervals; then add alcohol, 30 minims, and filter; to
the filtered solution add dilute nitric acid of the strength stated, 5
minims. The bath is now ready for use, and should be quite neutral.
5. Allow the prepared glass to remain in this bath from five to ten
minutes, according to the temperature. Move it up and down three or
four times whilst in the bath, in order to get rid of the greasy
appearance on the surface; drain it, but not too closely. When in the
frame, place upon the back a piece of common blotting-paper, to absorb
moisture, and the two lower silver wires should also be covered with
slips of blotting-paper; after which the sooner it is placed in the
camera the better.
6. The time of exposure can only be ascertained by practice--no rules
can be laid down; and I am unacquainted with any royal road, but that
of experience, leading to constant success in this most important point.
7. The plate having been taken from the camera and placed upon a
leveled stand, or held in the hand, develop immediately the latent
image with the following solution:
_Iron developing solution._--Protosulphate of iron, 1/4 oz.; glacial
acetic acid, 1/4 oz.; spirits of wine, 1/2 oz.; distilled water, 8
ozs.; mix. Pour on of this solution only enough to cover the plate
easily, commencing at that edge of the negative which stood uppermost
in the camera; move the solution to and fro until it has become
intimately mixed with the silver on the plate; then pour off into the
developing glass, and _at once_ return it on to the plate. When as much
intensity has been obtained as possible with the iron developer, it
should be thoroughly removed by washing with water. Any intensity may
be obtained afterwards by using either of the following solutions:
8. _Intensifying solution._--Pyrogallic acid, 6 grs.; glacial acetic
acid, 1/4 oz.; distilled water, 6 ozs.; mix. A few drops of a 30-gr.
solution of nitrate of silver, the quantity to be regulated according
to the intensity required, to be added, at the moment of using, to as
much of the pyrogallic solution as may be necessary.
_Intensifying solution_ (another form).--1. Pyrogallic acid, 8 grs.;
citric acid, 20 grs.; distilled water, 2 ozs. 2. Nitrate of silver, 8
grs.; distilled water, 2 ozs. Mix small quantities of the solutions 1
and 2, in equal portions, the moment before using.
The pyrogallic solution, made with good acetic acid, may be kept for
a month or more in a cool place. Nevertheless, if the conditions of
light and situation are unfavorable, I should prefer this solution just
made. The iron solutions act best when freshly prepared.
It is supposed by some that a prolonged action of the iron developer
produces fogginess. This may be the case when impure or improperly
prepared collodion is used, but certainly not when the preparation is
pure and of the proper quality.
When the image is sufficiently intense, wash freely with common
filtered water; then pour on a saturated solution of hyposulphate of
soda, which should immediately remove the iodide of silver: wash again
well with water; allow as much as the plate will hold to soak in for
at least a quarter of an hour, changing the water occasionally, to
remove all traces of hyposulphate; lastly, wash the plate with a little
distilled water, stand up to dry, and, if required, varnish either with
spirit or amber varnish.
The following solution is also very commonly used for fixing the
negative:--Cyanide of potassium, 1/4 oz.; water, 12 ozs.
Attention to the following rules and cautions will assist the operator
in the production of perfect pictures:--
1. Do not disturb the deposit which will occasionally be found at the
bottom of the bottle containing the collodion.
2. Remove all particles of dried film from the neck of the bottle
before pouring the collodion on the plate.
3. Never use damp cloths, leathers, or buffs, for giving the final
polish to the plate. Negatives with an indistinct and muddy surface are
frequently produced from this cause.
4. Let the film set properly before immersion in the nitrate of silver
bath: its condition can be ascertained by gently touching the lower
part of the coated plate with the end of the finger.
5. Never omit to pass a broad camel-hair brush over the plate just
before pouring on the collodion.
6. Bear in mind that, as light is the producing agent, so will it prove
a destructive one: not less than four folds of yellow calico should be
used to obstruct white light; and in that case the aperture covered
should be no larger than is necessary to admit sufficient light for
working by. Examine occasionally the yellow calico: when this material
is used to exclude white light, it becomes bleached by constant
exposure. Do not trust alone to any colored glass; no glass yet made is
anti-actinic under all aspects of light and conditions of exposure.
7. When the negative requires intensifying, carefully wash off
all traces of the first developing solution before proceeding to
intensify. This operation may be performed either before or after the
iodide is removed by fixing.
8. Glass baths are preferable to porcelain, ebonite, or gutta-percha
baths for solution of nitrate of silver.
9. In using either spirit or amber varnish, before pouring it off, keep
the plate horizontal a few seconds. This gives time for soaking in,
and prevents the formation of a dull surface arising from too thin a
coating.
10. Rub the lenses occasionally with a soft and clean wash-leather, the
rapidity of action is much influenced by the brightness of the lenses:
their surfaces are constantly affected by moisture in the atmosphere,
which condensing, destroys the brilliancy of the image.
11. The white blotting-paper used for some photographic purposes is not
suitable for filtering solutions; that only should be employed which is
made for this purpose, and is sold under the name of filtering-paper.
12. _Hyposulphate of soda._--A great deal of rubbish is sold under
the name of this salt. As a test of its quality, 1-1/2 drachms should
entirely dissolve in 1 drachm of water, and this solution should
dissolve rather more than 4-1/2 grains of iodide of silver.
13. _Chemicals._--The purity of photographic chemicals cannot be too
strongly urged; the cheapest are not always the most economical.
The commercial preparations are generally not to be depended upon,
as these, though perhaps unadulterated, are, strictly speaking, not
chemically pure. It is best to procure them from well-known chemists,
who understand the purpose for which they are intended, and make the
preparation of these substances peculiarly a branch of their business.
14. Never leave chemical solutions exposed in dishes: when done with,
pour them back into glass-stoppered bottles, and decant for use from
any deposit, or filter if necessary.
15. In all photographic processes it is absolutely necessary to be
chemically clean; and this sometimes is not easy. As a rule, never be
satisfied with cleanly appearances only, but take such measures as
shall insure the absence of all extraneous matter in preparing the
solutions, cleaning the glasses, dishes, etc.
16. All stains on the hands, linen, etc., may be removed by means of
cyanogen soap or cyanide of potassium, which should be applied without
water at first, then thoroughly washed off. To assist the operation,
the hands may be now gently rubbed with a fine piece of pumice-stone,
when the stains quickly disappear.
For more perfect and complete directions, the reader is referred to any
complete work on photography.