What Is A Black Light?
If you spend enough time reading about movie posters, you will occasionally come across the term "... visible under a black light". We have been asked a few times what that means, so thought it was about time we addressed the question on the blog.
What Is A Black Light?
A Black Light is a light source such as a lamp or torch that emits long-wave ultra-violet (UV-A) light waves and very little visible light.
As you can see in the diagram below, the wavelength of light being emitted is at the very limit of human eyesight.
Why Is A Black Light Useful?
Use of Black Lights can be traced to the early 1900's, when Robert Williams Wood invented Wood's Glass, a material that filtered visible light waves, leaving ultra-violet and infra-red waves visible. Used during World War I for clandestine communication, it also found uses in medicine and biology.
Another exciting field was a Black Light's ability to create ultra-violet fluorescence.
Fluorescence occurs when a material emits light of a different wavelength to that it has absorbed.
Examples of Fluorescence
During the 1930's the Switzer brothers from Berkeley, California began experimenting with a Black Light and the contents of their father's pharmacy. They identified naturally occurring compounds that provided fluorescent effects. Using these they were able to create a range of fluorescent paints and set out looking for commercial opportunities.
One of these was the Fluor-S-Art Co., incorporated in 1934 to sell black light paints for advertising purposes. This resulted in a partnership with a subsidiary of Warner Brothers Pictures to develop fluorescent paints for movie posters and advertising displays.
By the 1960's their company had diversified into flaw detection of machine parts, military applications, detergents and workplace safety. Their company was known as the Day-Glo Colour Corp.
During the counter-culture revolution of the swinging sixties, fluorescent art and posters were developed, including the album artwork for Cream's 1967 album, Disraeli Gears.
1985's movie goers will also have seen fluorescence used to great effect in the opening titles of James Bond's A View To A Kill, accompanied by the fantastic Duran Duran theme tune!
Use In Modern Day Movie Posters
These days, inks with fluorescent properties may be used to enhance colours in movie posters. There are also stories of them being used to hide messages on posters, although we believe most (perhaps all?) of those are urban myths.
Fluorescent inks are however used to reduce the risk of counterfeits and a great example is the 'Style A' teaser poster for Star Wars Episode I: The Phantom Menace, made available to members of the Star Wars Fan Club.
Taking a look at the rear of this single-sided poster under normal light does not reveal anything significant.
However, turn off the lights and shine our Black Light torch upon it and something starts to emerge.
Focus the Black Light upon it and a reversed Lucasfilm Limited logo is clearly visible. This is only visible under Black Light and we always check for it when we receive an example of this poster.
By the way, A View To A Kill isn't the only movie nod to Black Light and fluorescence! Over to The Guardians of the Galaxy and the one and only Peter Quill...
Adam and the Art of the Movies team.