Articles

The Black Light

The black light is a tool that can give you quick and non-destructive results in your examinations of Indian artifacts.  It and the magnifying glass or 10X hand lens are probably the most useful hand held tools that the artifact collector can use.  But you must learn how to use the black light in order to be able to detect restorations and reproductions.  This paper will present a brief explanation of the black light and how to use it.

The black light is really nothing more than ultraviolet radiation which is a form of energy invisible to the human eye.  This tool, which is useful to collectors of many types of antiquities and collectibles (Indian artifacts, glass, china, paintings, etc.), is simply a filtered fluorescent tube and source of power to illuminate it.  They come in AC and DC hand held models and non-portable AC cabinet mounted types.  There are two types of the black light - longwave and shortwave.  The shortwave black light is used in medical work and in some cases the examination of minerals but it should not be used by you because it can be dangerous.  The wave lengths of the shortwave light are intense and can burn your eyes and skin.  These wave lengths are measured in nanometers and only the longwave black light that produces wave lengths between 320 and 380 nanometers should be used.  The black light will be marked as to the type on the tube, usually along with the name of the manufacturer and /or model number.  The true longwave black light will be marked with the words “Black Light Blue” or the letters “BLB”.  Use only these.  Do not rely on any markings on the housing since the tubes may have been switched.

The cost of any black light is based upon three criteria: the type of housing; how the power is supplied; and how filtered or “pure” is the light.  The purple or blue glow that is seen when the black light is used is actually white or invisible light that is not pure or filtered out.  Remember that the energy from the black light itself is invisible.  The better the filtering mechanism, the better the black light will perform but that also will increase the price.  You will probably use a small portable black light, the least expensive of which will be powered by small batteries and will generally cost in the $25 to $75 range.  The 110 volt models and the better DC models with rechargeable batteries usually cost more than $100 but will give better results.

This paper will not go into a lengthy explanation of exactly how and why the black light works but it will explain what will happen and the results you can expect.  When you examine an artifact with a black light, you are bombarding the surface of the item with ultraviolet radiation.  The electrons in the artifact will absorb this radiation and will release visible light.  This is called fluorescence and it is what you are looking for.  Restored artifacts, since they are made of dissimilar materials (i.e. stone and Bondo or ceramics and water putty), will absorb the ultraviolet radiation in an unlike manner and the restored and un-restored areas will fluoresce differently.  When you examine an artifact, say a pottery vessel, you are looking for an even fluorescence color throughout the object which would mean that probably the vessel is solid and not restored.  If you observe different color areas or narrow oddly colored lines, this probably means restored patches or glue lines from piecing together a broken pot.  A vessel, though, may have been restored and painted overall in which case the black light will not show any restored areas since it will not see through paint.  In such a case, you will need to compare the fluorescence of the suspect painted vessel with a similar non-restored pot.  This can be tricky, though, because minerals in the ceramics and the surface patina can cause two very like vessels that were found side by side on the same site to fluoresce differently.  Remember you are looking for color differences rather than particular colors. 

Restored or re-chipped stone projectile points can also be detected with the black light because most any recent surface disturbance will react differently than what is seen on the original ancient surface.  Completely new faked artifacts can also be detected because old and new knapped materials will not fluoresce in the same manner.  Of course, this will also work for stone axes, bannerstones, pendants or most any other category of ancient or reproduced Indian artifacts. But you must carefully study and analyze and understand how the black light reacts to true authentic ancient artifacts. 

The usage of the black light is simple.  The artifact to be examined should be placed against a black or dark background.  A piece of black fabric usually works very well.  Also the darker the room where the examination is taking place, the better will be the fluorescence.  Generally you should use the black light just as you would use your magnifying glass – with a slow and thorough investigation of the artifact.  It is best to conduct the test for the suspect artifact alongside a known authentic one for comparison purposes.  It is most important to have the artifact(s) being examined very clean.  Dirt, dust, grease, etc. will seriously affect the results.  When you activate your black light and begin the study of the items, look immediately for color differences.  Remember you are looking for different fluorescent color reactions if you suspect the artifact is bogus.

Now do not immediately acquire a black light and begin examining your artifacts for guaranteed authenticity.  This is not magic and it certainly is not 100% accurate.  The fluorescence you see is not always a guarantee of age.  Never forget just how good the fake makers and unscrupulous sellers are.  Use the black light as simply another tool to assist you in your collecting adventures.  And always remember that your best tool is the knowledge you acquire by studying authentic ancient artifacts and learning more about them

Black lights can be acquired from retail electronic stores and on-line.  You should not have any trouble finding a supply if you decide to buy one.  Happy black lighting!

 

REFERENCES:

 

THE BLACK LIGHT BOOK                                               1992

            Antique & Collectors Reproduction News

 

Maus, James E.                                                           1997

            “The Black Light: A Useful Collector’s Tool”, PREHISTORIC AMERICAN, 

            Vol. XXXI, No. 3