For collectors of Pre World War II paper memorabilia—whether it’s baseball cards, photographs, scorecards, advertising posters or booklets— there is a sophisticated yet inexpensive and easy to use tool for quickly identifying many modern reprints and fakes. This tool is called an ultraviolet light or black light. While there are many uses for black light in collecting and beyond, this article shows how it can be used to identify modern paper and cardstock.

How Black Light Works
A black light allows the collector to see things invisible under normal daylight. Ultraviolet light is outside the human’s visible spectrum, meaning it cannot be seen by human eyes. However, in a dark room materials can fluoresce (glow) 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. The fluorescence varies in color. Under ultraviolet light, gemstones and antique glass can fluoresce red, yellow, green, purple, white and orange. The 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 and cardboard stocks.
Starting in the late 1940s, 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. 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, family snapshot or most types of today’s computer paper under a black light.
If paper stock fluoresces very bright as just described, it almost certainly was made after the mid 1940s. 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.
The beauty of this black light test is you can use it on items you aren’t an expert on. You may be no expert on 1920s German Expressionist movie posters or 1890s Canadian fishing industry pamphlets, but you can still identify many modern reprints.

Tips on effective use of black light
A black must be used in a dark room, the darker the better. Take a minute or three to let your eyes get adjusted to the dark. The paper memorabilia being examined should be on something that does not fluoresce. Something that does not fluoresce will appear black under black light. If your background fluoresces too brightly, it can be hard to judge the fluorescence of the memorabilia.
It’s best for the memorabilia to be removed from any top loader, glass, plastic sleeve or other holder. The holder itself can fluoresce or otherwise mask the memorabilia’s fluorescence. Shine the black light on all sides of the memorabilia. Some trading cards and photographs have coatings on one side.
For comparison purposes, you may wish to have a shard of modern paper that fluoresces brightly. Between the black table and bright shard, you will have a range on the spectrum for comparison.
Practice using the black light. See what items from all years look like under black light. Feel free to look at magazines, books, typing paper, glass vases, plastic.
It is the responsibility of the reader to learn the safety precautions. Directions that accompany the black light should be read and followed. With proper caution, black lights are safe. Some safety recommendations include: Do not look directly into the bulb when on. Use for no longer than 15-20 minutes at a time. Wear long sleeved dark colored clothes and UV protective goggles if used a lot.

Purchasing a black light
The collector should purchase a longwave black light, as opposed to a shortwave black light. Shortwave is important in a few specialty areas, including identifying stamps and gem stones, but longwave is the safest and all you need for most paper memorabilia. Luckily, the most common and inexpensive black lights on the market are longwave.
Black lights are widely available and have a wide variety of uses. They are used by geologists, chemists, detectives, art museums, plumbers and even scorpion hunters (scorpions fluoresce). Black lights are sold by many science, hobby or rock stores. They can be purchased online. You will find pocket-sized longwave models on eBay for well under $20each.

* * * *

David Rudd Cycleback is an art historian, specializing in issues of authenticity. He was a contributing scholar for the Encyclopedia of Nineteenth Century Photography, and author of the guides Judging the Authenticity of Early Baseball Cards and Judging the Authenticity of Paper Photographs.