I haven't seen the original article.
Here's my guess at the meaning, going from the poorly worded paragraph you've quoted.
The project uses high pressure mercury vapour lamps which take five minutes to warm up and produce full light output.. This is because the light producing discharge requires mercury in the gaseous state and when the lamps are cold, the mercury is still a liquid. Unfortunately the lamps can be damaged if started when the mercury is in a gaseous state and the lamp pressure is still high so they need to be left to cool for five minutes before they are restarted.
Most modern high pressure mercury lamps don't produce much UV because they are encased in a phosphor coated shield which converts most of the radiation to useful visible light. The shield can be removed but this might be a bad idea as some lamps have a safety device which stops them from working with the shield removed. Even with the shield removed, most of the UV radiation from a high pressure mercury lamp is in the UV region which isn't optimal for exposing photosensitive bulbs.
You can buy special black light high pressure UVA lamps designed for blacklight cannons (also called beehive lamps) which are used for theatrical effects and can be purchased from, stage, DJ and audio supply shops.
Here's an example of such a lamp:
http://www.planetdj.com/i--LL-400BLBNote that you'll need a suitably rated ballast and igniter to use the lamp, although you can buy lower powered lamps with it built-in.