The ultraviolet light, more commonly known as a black light, is a sophisticated yet inexpensive and simple to use scientific instrument. Black light is used in a wide range of hobby, professional and scientific areas. Police detectives use it in homicide investigations. Medical doctors use it to identify conditions. Museum curators use it to help date paintings. Collectors use it to authenticate glass vases. World War II fighter pilots used it to navigate at night.
This column looks at how longwave black light is used by collectors, dealers and auction houses to help authenticate and identify fakes and forgeries of many kinds of sport and non sport memorabilia. This includes trading cards, posters, scorecards, tickets, postcards, photographs and even uniforms.
The start of this column looks at black light itself —what it is and how it works—then gets into the specifics of how collectors and dealers can use it for their benefit. Do not worry, you don’t have to be a scientist to use black light. The scientific background is offered so you have an idea how it works.
What is black light?
Black light, aka ultraviolet light, is a range of light invisible to human eyes. Black light is a part of the light spectrum, the entire light spectrum ranging from X-rays to infrared light. In between X-rays and infrared light include visible light (the light and the colors humans can see) and black light.
There are two types of black light used by humans: shortwave and longwave. This article is only about longwave black light. Shortwave is useful in areas, including identifying gems, but is more dangerous. Used properly longwave black light is safe for kids and adults, and is even used in elementary school classes.
What makes black light special is that, while invisible itself, it makes many things fluoresce, or glow in the dark. Under black light, materials can fluoresce the range of colors, bright to dim. Many of us have experience how black lights make our white shirts and socks fluoresce brightly. As you will see, it is this fluorescence that helps in authentication and forgery detection.
What is black light, the tool?
a common style of hand held black light>>
To use black light, you need a black light, the tool. This tool is a light that was made to emit only, or mostly, black light. Black lights are sold commercially and come in a variety of sizes and styles. Many look like conventional lights and flashlights. Some are small enough to fit in your pocket. They are sold in a variety of places, including rock shops (black lights are used by geologists) and eBay. A good black light can be purchased for under $20. The average collector and dealer uses an inexpensive handheld size and AA battery powered. Remember to make sure the light you are purchasing is longwave, not shortwave. Luckily, most models sold are the longwave.
How to use a black light
Black lights are easy to use. Examination of an object with black light must be done in the dark, whether in a dark room during the day or at night. It is best to be in the dark for a couple of minutes first to acclimate your eyes. When you're ready, turn on the black light and shine the black light on the material. Most black lights emit a small mount of visible light so that you know it's on and working.
It's best to examine an object against something that does not fluoresce. If the background gives off light it may affect results.
If you have a black light, you can shine it around your house in the dark and see lots of things that fluoresce. Some around the house things that often fluoresce include computer paper, laundry detergent, eye glasses and modern postcards.
How Does Black Light Make Things Fluoresce?
The fluorescence, or visible light that is emitted from a material when black light is shined on it, happens at the atomic level.
Just as with sunlight, heat and x-rays, black light is a form of energy. When black light is shined on a material, whether the material is glass, plastic or paper, energy is being added to the atoms of the material. The atoms can only hold this extra energy for a short amount of time before having to give it off. The atoms give off the energy in a different form than received. The atoms receive the energy as black light, but may give the energy off as heat, ultraviolet light, infrared light, visible light or, often, a combination of these. What form(s) of energy the atoms gives off is dependant on the makeup of the atoms.
If visible light is emitted by the atoms, that is the fluorescence we see. The color of this visible light is also dependent on the atomic make up. If the atom gives off just heat, ultraviolet light or infrared light, there will be no fluorescence. In a darkened room this material will remain dark.
How does black light help collectors, historians and professionals
The color and brightness of fluorescence for a wide variety of materials is known, often published in articles and books, and the person with a black light can make sure an item fluoresces the color it is supposed to. For example, collectors of antique Lelique glass use black light to help authenticate. Antique Lelique glass fluoresces a bright yellow under black light, while modern versions do not. The glass collector doesn't have to be an atomic chemist to test the glass, just know the colors.
The rest of the column looks at some specific memorabilia areas where black light is used by collectors and dealers.
Identification of Modern Paper and Card Stock
As black light easily identifies many, though not all, modern paper stocks, the black light is commonly used by collectors and dealers to identify modern reprints, forgeries and counterfeits of Pre World War II sports cards, postcards, posters and other paper and cardboard memorabilia. Many antique items have been identified as fake simply by shining a black light on them.
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 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, snapshot or most types of today's printing paper under a black light.
If paper stock fluoresces very bright as just described, it almost certainly was made after the mid 1940s. If the item is supposed to be from before WWII, it’s obviously a modern fake.
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, 1930s lace>Hollywoodlace> movie photos and 1890s Canadian fishing industry pamphlets, but you can still identify many modern reprints.
Identifying vintage and modern counterfeit sports cards
Beyond just Pre-War issues, black light is useful in identifying reprint and counterfeit sports cards from all years. The following link goes into the numerous basic techniques collectors can use to identify counterfeited cards from Mickey Mantle to Michael Jordan rookies. The links shows both black light and other simple techniques, like looking at a card’s gloss and opacity.
Identifying restoration and alterations
Many items are restored or altered by the addition and/or subtraction of substances, including paper, paint, varnish and glue. Items that are restored include furniture, paintings, trading cards, prints and photos. A seller should disclose restoration at sale. However, too many don’t ,either due to ignorance or dishonesty.
A longwave black light can identify or confirm much restoration. This is because the added material will often fluoresce differently than the original. If a tear to a painting is repaired, the added glue, paint or varnish may show up clearly under black light.
Very old paint and varnish tends to have little to no fluorescence. Antique toy collectors often use a black light to judge if the paint on an antique toy is original or modern. Antique fishing lure collectors use a black light to judge if an expensive antique lure has been varnished recently.
Identifying baseballs with autographs removed
Some dealers and collectors remove autographs from baseballs for aesthetic or financial reasons. For example, a single signed Joe DiMaggio baseball will be worth more than the same ball with Bip Robert’s signature beneath Joe’s. Remove the Bip’s signature and the ball can sell for more (Duly note that I am against this practice and am in no way promoting it. Leave poor Bip alone!). While the removal may be difficult to see under normal daylight, the restoration will often show up under black light. The chemicals and substances used to remove the ink will fluoresce different than the rest of than ball.
I examined an autographed music record where the personalization, not the band member’s autograph, was professionally removed. With the naked eye I could lightly see where it was rubbed off with some sort of chemical. Under black light the chemical fluoresced brightly.
Clothing including sports uniforms
I don’t specialize in sports jerseys or movie worn costumes or antique kimonos or anything like that, so my experience with black light and cloth is minor. Collectors, dealers and historians in this area will be able to do their own research. Check out your own jersey or cap collection to see what you see.
As with paper, optical brighteners have been added to some modern clothing and will fluoresce brightly under black light. This will often make the 1995 retro version of a 1920 style shirt simple to identify as modern, as the entire shirt or just the patches or tags fluoresce brightly.
Modern alterations on antique clothes using new will often be apparent under black light. Modern white thread often shows up easily. If someone tried to fraudulently sew on foreign patches or wash tags on an old jersey, the brightly fluorescing thread itself can identify the alterations as recent.
I put my dark blue New Era Seattle Mariners baseball cap I wear under my black light. The black light alone proved it modern as some of the front emblem, the inside tags and some stitching fluoresced brightly.
One thing to be mindful of is that washing machine detergent often has optical brighteners. Thus, if a genuine antique jersey is washed, there may be some, if minor, optical brightener residue from the detergent. Granular detergent is usually easy to tell as it has a distinctly granular pattern under black.
As with comparing baseball cards across a set (see above article link), someone with access to a large archive of game used sports jerseys might find interesting trends in fluorescence. As the jerseys of a particular Major League baseball team’s jerseys were likely made, or likely mostly made, with the same cloth, a black light might be able to help identify fakers. It’s likely that the genuine team felt patches or sewn on player lettering for a team will have distinct trends in fluorescence. If a forger tried to add recently made patches or player name plate, the patch and name plate may fluoresce differently than the known originals. Again, I have not personally examined any game used or team issued sports jerseys or caps, so I am offering ideas and possibilities for others’ research.
There are affordable pens and stamp pads that use invisible ink. The pens look like regular felt tip pens and the ink pads like every day ink pads, and are often sold by the same folks who sell black lights. The ink in these items is invisible under normal daylight, but fluoresces brightly in the dark under black light.
People use invisible ink for a variety of practical security and identification uses. People invisibly write their name or identification number on valuables, like paintings, computer and china, so they can be later identified in case of theft or dispute. An online seller of computer parts or dolls may have a problem with customers who return damaged goods they didn't purchase from the seller: The dishonest buyer buys a new item, returns a different used or broken item for refund and gets to keep the original for free. If the seller puts an invisible ink dot on the item before shipping she can be sure that the customer is returning the original. A jersey seller worried about buyers adding fake game used could write in the collar “Sold as team issued only.’ So it could be verified as the real deal, Major League Baseball put a specially shaped invisible ink mark on the ball Barry Bonds hit for his 73rd home run in 2001.
(c) David Rudd Cycleback. Cycleback is a trademarks, with all rights reserved.