[SML] LED Blacklights

Thu Apr 9 08:51:59 UTC 2015

Without wishing to scaremonger, can I just point out again that it is crucial importance that you pay good attention to the wavelength and DO NOT USE a luminaire that produces UVB such as a tanning tube or a glue curing system.  Google it and you will see how dangerous it is :  retinal damage, skin cancer,- Its like saying out in the sun without protection  in the  desert. No sunglasses would help.   Even using  the 'safe" UVA,  fluorescent tubes you really ought to do a full risk assessment for your own protection.  Never star at it, always use your peripheral vision to examine it.  UV radiation enters the eye  in large amounts but as the brain does not interpret this as light, neither the iris reacts to protect the eye nor does the other system "Rhodopsin bleaching"  take place. Because of this the retina is working overtime, which can cause problems.   If you have recently had cataract removal this takes away another level of filter.  Sensitive people in the audience can be affected, and I have received complaints of headaches from actors. Although I believe them to be unrelated, one has to take them seriously, so having the data and a risk assessment  to hand is important.  After staying up all night to paint a VU cloth under UV Light I  personally had blinding headaches  for weeks afterwards. That of course is just my experience and I did get eight solid hours of it.
. 
On the other hand , UV is a long-established theatre technique which can be very safe if used in  moderation.   I am interested in the Luxeon 385 Nm unit, it looks really useful.

A great technique is to use it in combination with red incandescent ( is that now a rude word?) lamps. The great illusionists with “Black Light’ acts where things float magically about the stage and human beings can disappear,  use a small pros arch with UV tubes behind and a row on dim red lamps on the front.  Costumes and makeup are UV treated to look as n normal as possible. This fools the eye by contrast  into believing that beyond the pros arch is pitch black and also gives the retina something to stabilise on.

DK

> On 9 Apr 2015, at 02:51, Robert Engel via Stagecraft <stagecraft at theatrical.net> wrote:
> 
> 
> On Tue, 7 Apr 2015 19:06:45 -0700, Joe D <jdunfee12 at yahoo.com> wrote:
> Do you know the wavelength of the unit?
> The difference between the two pictures seems quite subtle.  Why did you do the UV light at all? Did you sometimes use it without the blue strip lights?
> 
> I don't see the wavelength in the spec sheet for the light.  I believe it's 395-405nm.  It did have a vague violet visible color that was only really seen if the rest of the stage was dark.  I considered using some of the 10w LED flood light lamps in the UV 'color' from AliExpress.  I got one as a sample via the slow boat from China, and thought it was too much "flood" for my situation. I would also have had to home brew my own DMX control / constant current driver, as dimming was a design requirement for all scenes other than the instant on of the initial "reveal."  The Monoprice lights were chosen mostly due to ease of use - I can order and get them in a week.  Plug them in, address, and be done.  Overall, I recommend them for use with the budget in mind.  i wasn't unhappy with 54w for full stage coverage of a drop, and I couldn't see any flicker at all.
> 
> The concept for the use of UV in the show was as a transition into the 'city' with 'office lights' in buildings. The UV was not used in the show without the strips to provide an outdoor / night look. The moon projected on the black curtain was the 10w RGBW LED Pinspot from Monoprice.  (I had to resist having a red moon... and my wife (the Producer / TD / set designer) did not allow me to have a Sweeney Todd - "City on Fire" look from the red roundels in the strips... not that it would have worked in the story line, but... City on Fire, City on Fire...)
> 
> We didn't have a photo call, all of my pictures are "cellphone" quality and don't do the effect justice for was it was in person.  It worked out quite well, looking like office lights were left on in the buildings. The UV reactive windows were painted with yellow UV / white normal Wildfire paint.
> 
> A picture during the construction phase with the UV (with blue) with some house lights, stage works, and curtains open.
> https://www.dropbox.com/s/8ttlw56bo6s2mau/2015-03-12%2020.01.17.jpg?dl=0
> 
> AliExpress UV Flood:
> http://www.aliexpress.com/item/DC-12V-10W-Ultra-Voilet-UV-led-outdoor-floodlight-UV-395-405nm-LED-flood-light-for/1074714649.html
> 
> Robert Engel
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