Question #2

The blacklight or UV-A is the longest and safest wavelength region 
of UV and also the lowest energy.  It is very useful in today’s
society.  There is almost an unlimited number of commercial and 
personal home uses. Blacklights are used in hotels, motels, nursing 
homes, for law enforcement, day care centers, schools and universities, 
hospitals, rehab centers, medical offices, restaurants, 
food processing plants, pharmaceutical and electronics manufacturing, 
clean rooms operations.  They are also used around the house for at 
home sanitation, sanitary inspection, bacterial detection, pet 
stains, and lice detection.  Blacklight fluorescence is used today 
for many types of inspections.  The light makes processes easier 
in jobs like forensics, antique and art inspection, quality control, 
and healthcare.  

Blacklights have the ability to illuminate chemicals or substances 
that would otherwise be invisible to the human eye.  They have the 
ability to reveal otherwise invisible evidence at crime scenes 
and can help find the causes of some fires.  Blacklights are 
very useful in art inspection.  Different chemical properties 
become apparent under a blacklight.  For instance modern paint 
will fluoresce or glow under a black light, older paints will not.  
This can be used to determine whether a painted object is an antique 
or a newer reproduction as well as to determine whether a 
piece has been "touched up" and if so, how extensive was the repair. 
The same technique can be used to detect repairs on antique 
porcelain as the old finish will not glow under a blacklight, and 
the newer material in the repair will.

Synthetic fibers, such as rayon and polyester, made since WW2 all 
fluoresce. This allows detection of new military uniforms, new 
quilts, new doll clothes, etc. Even if old fabric is used to repair 
an old quilt, the new thread will fluoresce. A quilt from 1800 is 
less likely to fluoresce, while a quilt made in the last decade 
probably will. Mass produced laundry detergents from the current 
and past decades have contained additives that make laundry whiter 
and brighter. These additives can make textiles fluoresce 
under a black light, which would lead a person to believe an 
antique quilt/textile, washed in these detergents, was newly made. 
And while many newly made fabrics and threads do fluoresce, there 
are also fabrics and threads that do not fluoresce.  Blacklights can 
be very important for collectors of antique arts.

Stores can make good use of blacklights.  Fakes and forgeries often 
look different under blacklight. Many business owners keep a blacklight 
behind the counter to check bills for the standard markings which 
are designed to glow under UV. 





Artworks that are touched up to look matched in color to the naked eye 
will often show stark differences in fluorescence due to changes in 
paint. UV can allow you to see many of these otherwise hidden details.  
They can also check identification cards using blacklights.  
Alterations and lack of intentional features, such as holograms, that 
were put in only the approved documents can show up well under 
UV lighting.

Blacklights can be especially useful in the healthcare industry.  
Blacklights are used to help effects of Psoriasis, and UV light is 
used in many medical treatments. UV is at the upper end of full 
spectrum visible light which appears to help in treatment of 
Seasonal Affective Disorder. Vitamin D is produced when the skin 
is bathed in UV light, and exposure to UV helps the body absorb 
calcium. Recent medical developments include fluorescent 
dyes used in conjunction with blacklight to identify cancerous cells 
in the internal organs of patients

Although often overlooked, a blacklight could be a very useful tool 
in this day and age.  Blacklights and other UV lights have the ability 
to assist the human eye in detecting things that would otherwise be 
unknown.  Everything from crime scenes, healthcare, to personal use 
can find benefits from blacklights.  Society can also find more uses 
for blacklights in the future including revealing biological and 
chemical agents in the air.  


Introduction|Physics of Blacklights|Question 1|*Question 2*|Links|Conclusion|Works Cited|People