Definitions
“ Ultra Violet“, usually shortened to UV, is also known as “Black Light”

You can often hire UV lamps from you local theatrical supplier (or Disco dance equipment rental shop).

Warming Up
Most of the larger UV lamps take a few minutes to warm up, so it is normal practice to switch them on a little while before they are needed. This is quite often during the scene which comes previous to the one in which you want the effect. The drawback to this is that, as they slowly start to activate, so items on the stage start to glow i.e. light coloured costumes, handkerchiefs etc. which rather “gives the game away” that a UV scene is in the offing. We used to solve problem this by mounting the UV lamp in an accessible position - often on the floor- and temporarily putting a cardboard sheet in front to stop the light spilling until it was required.

Cheap but effective
However I recently used some “Black lights” which were bought from a “Catalogue Shop” - Argos (but are we allowed to mention that trade name Annlaug?) and, although weaker than the professional version, they were instant start and the minute they were switched on they were fully active. These particular lamps were also surprisingly cheap so we had three of them and disported them around the stage to give the necessary cover.
Incidentally, I avoid looking straight into an Ultra Violet lamp because it affects my eyes and for a few seconds afterwards I find it hard to focus.

Using UV Fluorescent Paint
The type of paint which is energised by UV light is called Fluorescent paint. This is not to be confused with “Phosphorescent” paint which has an afterglow once exposed to daylight. Phosphorescent paint is very useful for marking objects backstage- stair treads, stage weights etc

When I am painting with Fluorescent paint, especially the so-called "invisible", colourless version, I work as near as I can in darkness with the UV lights switched on. That way I can see what I am/have painted. This is great fun, for the paint glows; the brush glows; my overalls glow; and if I spill any onto the stage, then the floor glows as well.

Are you putting on a performance during daylight? If so, are you able to black out the hall windows to make the UV scene effective?

Appropriate time to use the UV effect in our Musical.
The dilemma here is two fold...
Painting:- Painting with fluorescent paint is not as successful as, say, poster or acrylic paints. you can’t get the subtle gradations or mixes. And as the bulk of the performance of our “Planets” will be viewed under the normal stage lights then I suggest you prepare a separate set of coloured cardboard discs the same size as the regular “Show” Planets but painted with the fluorescent colours. One disc per Planet child.

When to use the Ultra Violet display?
Obviously you can’t run the entire performance under UV lights alone. The audience would miss much of the action as many of the cast would not be in UV costumes. It would also be very tiring on the eyes.

I have seen attempts to solve this by running a UV scene with dimmed stage lights as well as the UVs, but on a small stage this results in a “dog’s dinner” of a performance with the UV elements only glowing when near the UV lamps (Annlaug - Roma’s ‘performance‘ being an example)

Dedicated Event
So the answer is to select a part of the show which lends itself to a dedicated UV event and I suggest this could well be the Round Song “Universe is Turning” Scene 5 (Page 16). Here’s one possible scenario:-

First verse under the normal stage lights with the round being sung and the “Planets” jostling as per the script. However, towards the end of this verse, in ones and twos the Planets unobtrusively leave the stage and collect their UV disc from the wings which they then hold in front of their existing front ones and return onto the acting area.

At the end of this verse, with all our Planets now holding their fluorescent discs, the stage lights are extinguished, the singing continues, and our Planets perform their ‘ballet’ under UV lights only, coming into orbiting-order as the script requires. This sequence would be quite a magical surprise moment. By the way, as each Planet child is carrying one disc which is only painted on the front, as they turn around so their planet apparently winks out.

During the applause at the end of this sequence the Planets return their fluorescent discs to the props person waiting in the wings.

The above, of course, is only a suggestion and if you find you’ve run out of choreographing ideas before the tune finishes, then transpose the ballet to only take place during the last verse.

An Alternative Solution
Are the children having difficulties singing this round? Do they need rigid conducting? Not easy in darkness!
Here’s an alternative. Instead of our ballet taking place during the singing, wait until they have finished all three verses under the normal stage lights, then repeat just the backing track and perform the UV ballet without any vocals. (Annlaug - this is assuming the backing track also carries a non-vocal melody. If this not the case then delete the above paragraph)