For collectors of Pre
World War II paper material-whether it's sports photographs,
theatre programs, movie posters, trading cards, scorecards or
postcards- there is a sophisticated yet inexpensive and easy
to use tool for quickly identifying many modern reprints and
fakes. This tool is called a longwave ultraviolet light or longwave
black light. While there are many uses for black light in collecting
and beyond, this chapter introduces how it can be used to identify
How Black Light Works
A black light allows the collector to see things not seen
under normal daylight. Ultraviolet light is outside the human's
visible spectrum, meaning that it cannot be seen by human eyes.
However, in a dark room different materials can fluoresce (give
off light) under black light. Most of us have experienced black
lights that make the whites on our shirts or shoes glow brightly.
Some materials fluoresce brightly, some not at all and the rest
somewhere in between. Fluorescence can differ in color. Some
minerals fluoresce yellow, some red and some blue. This quality
of fluorescence happens at the atomic level of the material.
Identification of Modern Papers Using Black Light
A black light is effective in identifying many, though not all,
modern paper stocks.
Starting in the late 1940s (1950s for photographic paper), manufacturers
of many products began adding optical brighteners and other new
chemicals to their products. Optical brighteners are invisible
dyes that fluoresce brightly under ultraviolet light. They were
used to make products appear brighter in normal daylight, which
contains some ultraviolet light. Optical brighteners were added
to laundry detergent and clothes to help drown out stains and
to give the often advertised `whiter than white whites.' Optical
brighteners were added to plastic toys to makes them brighter
and more colorful. Today's tooth whiteners contain optical brighteners.
Paper manufacturers joined the act as well, adding optical brighteners
to many, though not all of their white papers stocks.
A black light can identify many trading cards, posters, photos
and other paper items that contain optical brighteners. In a
dark room and under black light optical brighteners will usually
fluoresce a very bright light blue or bright white. To find out
what this looks like shine a recently made white trading card,
snapshot or most types of today's printing paper under a black
light. Your powder laundry detergent probably will fluoresce
If paper stock fluoresces very bright as just described, it almost
certainly was made after the mid 1940s and after 1950 if it's
a photograph. It is important to note that not all modern papers
will fluoresce this way, as optical brighteners are not added
to all modern paper. For example, many modern wirephotos have
no optical brighteners. This means that if a paper doesn't fluoresce
brightly this does not mean it is necessarily old. However,
with few exceptions, if a paper object fluoresces very brightly,
it could not have been made before World War II. Using this
test, the collector can weed out many modern reprints.
It is important that the collector gain practical experience.
This means using a black light to examine and compare the fluorescence
of a variety of items. With photographs, make sure you shine
the black light on all sides and edges. This is because the gelatin
or other coating on the front of the paper often prevents the
front from fluorescing.
The collector should follow safety. If used correctly, longwave
black lights are safe, and can even be used by kids. Factory
boxed black lights will come with directions.
Where to buy a longwave black light
Black lights and ultraviolet lights are widely available and
have a wide variety of uses. Geologists use them to identify
rocks, collectors of glass uses them for authentication, theatres
uses them to create special stage lighting. They are even used
to find scorpions at night. Black lights are sold by many science,
hobby or rock stores. I bought mine and tested it out at a hobby
store in my home town. They can also be purchased online. I
have seen hand-held models regularly offered for well under $20
each on eBay.
Be sure to purchase a longwave black light as opposed to a
shortwave black light. Shortwave is important in certain specialty
areas, like stamps and gem identification, but longwave is the
safest and all you need for photos and most paper collectables
like posters and postcards. Make sure to double check, but most
of the cheaper black lights offered on eBay will be the correct
(c) david rudd cycleback, cyclback.com
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