A simple method for preparing lantern slides

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Material Information

Title:
A simple method for preparing lantern slides
Physical Description:
Book
Language:
English
Creator:
Acree, Fred
Haller, H. L
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine (Washington, D.C )
Publication Date:

Record Information

Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 30352848
oclc - 781939737
System ID:
AA00023126:00001

Full Text



June 1942


United States Department of Agriculture
Bureau of Entomology and Plant Quarantine


A SIMPLE METHOD FOR PREPARING LANTERN SLIDES

By Fred Acree, Jr., and H. L. Haller,
Division of Insecticide Investigations


For the sake of clarity and emphasis, it frequently becomes
necessary to employ lantern slides for presenting various types
of data. Time and cost often make it inconvenient to obtain slides
prepared professionally by means of photography. On several oc-
casions this laboratory has resorted to an easy method of making
lantern slides by applying the subject free-hand directly on glass
with water-proof ink. They have served just as satisfactorily as
those prepared by the photographic process. No elaborate equipment
is necessary, and all the needed materials are readily accessible.
The detailed directions given below always have been found to give
a suitable slide. Minor variations, such as the use of white in-
stead of black ink, and adhesive tape instead of the regular bind-
ing tape, may be made, of course, to suit the individual taste.

No claim is made that the outlined procedure is original.
The method probably has not been used more frequently simply because
writing on glass is considered difficult. This obstacle can be
overcome by cleaning the glass slide thoroughly with a cleaning
mixture, as outlined below in detail. Ordinary washing with soap
and water does not penetrate the glass pores sufficiently to remove
all the grease and other materials which tend to cause the ink to
spread unevenly.
Materials required

Lantern-slide cover glasses (3-1/4 by 4 inches).
Fine, stiff-pointed steel pen.
Black waterproof drawing ink.
Cleaning solution.
Distilled water.
Ethanol, 95 percent; or acetone (C.P.).
Linen hand towel.
Black paper lantern-slide tape (1/2 inch wide),

The lantern-slide cover glasses and binding tape are the
ordinary commercial products and may be obtained from any of the
photographic supply houses.


ET-194






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Cleaning solution.--This solution may be prepared by adding,
with stirring, 500 cc. of concentrated sulfuric acid to 25 grams
of powdered sodium or potassium bichromate. Some of the salt will
settle out on standing. The dark amber-colored supernatant layer
may be decanted for use and cleans satisfactorily until it begins
to assume a greenish color. Great care should be employed in hand-
ling this solutionas it is very corrosive. The addition of water
to the cleaning solution generates much heat. Should it be desir-
able to dilute the solution with water, or when the spent solution
is being disposed of, the solution should be care full poured into
a large volume of water; the reverse order of mix should never
be employed.

Preparation of Glass. .. .

The standard lantern-slide cover glass is cleaned by placing
it in the sulfuric acid-bichromate cleaning solution until the sur-
face of the glass shows an unbroken film of water on being washed
free of acid. It is then thoroughly rinsed with distilled water,
dipped into 95-percent ethanol or acetone, and wiped dry with a
linen towel. Cotton towels leave a lint deposit which is difficult
to remove completely. The cleaned glasses should be held on the
edges to eliminate fingerprints as much as possible.

Inking the Slides

The suggestions offered by M. P. Jones Jour. Econ. Ent. 30:
461 (1937)) on points to be considered-in thle preparation of lan-
tern slides should be observed. It is pax.ti-nclarly- desir-able -to
remember that the drawing should be confije. ta a-space.not.over-
2 3/4 by 3 inches.

The subject of the slide is applied freehand to the cleaned
glass surface with a steel pen and waterproof drawing ink. It is
important to use a fine, rather stiff-pointed steel pen, the point
of which will have no appreciable spread under slight pressure.
In order to obtain lines of unwavering density, the pen should be
dipped about two-thirds of its length into the ink and then with-
drawn along the side of the bottle opening, the surplus being al-
lowed to drain. The ink is started flowing from the pen by first
drawing lines on a sheet of paper until the flow of ink becomes
smooth and steady. The pen is then ready for inking the glass
and should be used immediately, as any delay allows the film of
ink on the surface of the pen, point tQ dry, ..which prevents, the
transfer of ink to the &lass surfaQe.... Aaaonas,he_ shows





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signs of ceasing to flow, the pen should be dipped into the ink
supply, otherwise the'lines will become of uneven density and usual-
ly will be spoiled by retracing. The carbon base of the black
drawing ink will clog the feed of the steel point after some use.
If dipping the pen into the ink two'or three times fails td dis-
lodge the obstructions, the wet pen must be cleaned by carefully
wiping it with a cloth.

Finishing the Slide

When the inking process is completed, the slide is allowed
to dry, preferably face down on a suitable support. Any lint or
dust that may have collected is brushed away, and fingerprints are
removed by wiping with a towel damp with ethanol.

The slide may be used at this stage, although it is better
that it be covered with a second cleaned cover glass. The edges
of the two glasses are bound conveniently in the following manner:
The slightly moistened or "tacky" binding tape (if too much mois-
ture is present it will creep between the glasses) is laid on a
flat surface. The edges of the covered slide are rolled along the
center of the tape with slight pressure, the outside edges of the
tape are then pressed against the surface of the glasses by moving
the fingers in the same direction around the outside of the slide
from one corner to the next. The "ears" on the corners are simply
pressed flat before the tape becomes dry and will remain in place.

Slides prepared in the manner described can be used without
delay and have proved satisfactory after repeated use.




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