Rob is a Lighting Designer and Lighting Programmer and currently Senior Lecturer in Technical Theatre Production. He is also the Editor of On Stage Lighting and teaches stage lighting practice.
With financial belts tightening, people are getting reluctant to spend money on new kit. On Stage Lighting looks at getting more out of your existing lighting equipment – lantern maintenance and how to get more 300% light for free.
Image by chikaga jamie on Flickr
My car has never had the brightest headlights. The other night though, I really couldn’t see the road, even with the front foglights on. “It’s no good – I’m going to have to buy some new lamps. These ones have really had it now!” The situation got worse down dark country lanes and a thought suddenly hit me. I get out of the car, chuck a bottle of mineral water over each headlight, and rub the 5mm of mud and grime from the lenses. Off we go again – much better.
The point of telling you this is not because I’m the kind of person that normally washes the car with Evian ( the rest of my car is still filthy). The solution to the problem wasn’t buying new lamps, but cleaning up the old lenses – it improved the light output by at least three times.
Lampies often hear newbie techies complaining about the lighting kit in their school/drama club/church:
The trouble is, all our kit is old, knackered and not bright enough. We need to buy some new lighting gear!
Yes, the lighting equipment in many places is old. Sometimes it is broken. But more often than not it’s just dirty. The traditional time for theatres to do their lantern maintenance is the summer “dark” period – when there are no shows running. Let’s not wait until then. How about getting some lighting equipment maintenance done soon, ready for your Easter shows. You could get 3 times as much light for free.
What you need to maintain stage lights
- Somewhere to work – a table set up on stage or in your lantern store. Close to where most of the kit already is.
- A few tools – some fixtures need a bit of dismantling before you can clean the important bits. Screwdrivers, spanners and Allen keys cover most of it.
- Some cleaning equipment – Lint free cloths, J cloths, dry paintbrushes, vacuum cleaner, detergent, water. Some kind of lantern friendly solvent like Isopropanol.
- Your lighting fixtures – All cooled down and NOT plugged in.
Maintaining Spotlights, Fresnels, PC’s etc
Cleaning – Get rid of the dust
Dust is a pretty big feature in theatres and most of it seems to collect on your lanterns. Start by brushing down the outside of the fixture, using a vacuum cleaner with a brush attachment is quick. Pay attention to any cooling vents around the lamp housing (at the back of the lantern), making sure they are clear.
Move the yoke and other parts that might be hiding dust. Lighting hire companies use a compressed air gun to blast the crap out of everywhere but these need to handled with care – they can be dangerous. They also tend to chuck the dust up in the air, letting it fall back down on the kit the minute you have finished cleaning it.
If a spotlight is really grimy, you can use a damp cloth with a bit of detergent.
While we are working on the outside of the lantern, look at the power cable where it goes into the lamp housing. The cable clamp (cord grip) area is a common place for cable insulation failure and conductor breaks (you can spot these by noticing a strain/lump in the outer sheathing. Look along the length of the power cord, looking for kinks or slits in the insulation, particularly where the cable enters the plug. It’s worth gripping the power cable and giving the plugtop a sharp tug – if it comes off in your hand, there’s something wrong 😉
Open up the lantern
Now we’ve got the worst of the external dirt off, we can open up the fixture.
Getting into a lantern varies depending on the type/make but you can usually access the lamp housing via the door used to change the bubble. Often a screw or catch is used to keep it shut. Once into the lamp housing, remove the lamp, taking care not to touch the glass bubble with your fingers. Put the lamp somewhere safe.
On a fresnel style fixture, you should be able to access all of the interior from here. Getting to the lenses in profile spots (ERS in the US) can take a bit more work. Modern fixtures have easy access lens tubes with covers/doors that open or a tube that come off easily, allowing access to both sides of the lens. Older fixtures take some more dismantling – a very common lantern in schools and churches is the dreaded Strand Quartet. (There could be a whole other article on “Why I hate Quartets” but …)
If you are maintaining a lot of Quartet profile spotlights, get ready for some heartache. Quartet lens tubes are notoriously difficult, requiring the removal of 4 long bolts that hold the tube and the entire gate assembly to the lamp housing. Sit the Quartet on its lamp end, lens tube facing up and level with the yoke on the bench to stop it falling over. Remove the 4 long bolts and carefully lift off the tube, making sure that all the other parts don’t lose their position. Stick a couple of bolts back in temporarily while you are cleaning the lens tube, to keep it all together. Othwise, you could end up with a box full of spares instead.
Using a vacuum cleaner, brush and suck any dust/cobwebs from the inside. You can also suck the top level of dust off the lenses, making less mess when polishing later. Vacuum the inside of any cooling grills and make sure there is no dust left around the lamp tray – dust is combustible.
Cleaning the Lenses and Reflector
Matt recently asked a question about cleaning lenses. This is the bit where you really get value for money – in the form of more light.
Clean and polish up the reflector (silver bit behind the lamp). Most reflectors are often clean on the inside face so you probably won’t need too much elbow grease. If the reflector is spotted, dull or has a lot of marks it’s unlikely you will be able to “polish them out” without taking the mirror coating off. Just give ’em a clean.
Cleaning the lenses is much more satisfying. Most lenses have a good layer of dirt on them which can be wiped away with a weak detergent/water mix. Avoid getting grease on the lens from fingers, under the sticky dust a lens is usually pretty clean.
You should never use standard glass cleaners or abrasive polishes on the lens – ETC (makers of the Source Four) specifically warns against this in their User Manuals. The Source Four lens has a special coating that can be damaged by the wrong cleaners. If you need to use a solvent, Isopropanol is a relatively friendly to most things , not to be confused with Acetone (nail varnish remover). Isopropanol also evaporates from the lens quickly, leaving very little residue. Old school guys used Meths as a lens cleaner, which does a nice job on glass but is very flammable and I wouldn’t give it any guarantees when it comes to modern lens coatings.
Work on both sides of the lens and don’t forget that profiles spots, particularly zooms, have two lenses.
Visual Inspection Inside
While everything is accessible, check a few points of weakness on any lantern.
Electrical Parts Inspection
Check the interior cable for chafing or splitting of insulation. Make sure that the ceramic parts, including the lamp holder and terminal blocks, have no burns or brittleness. See that screw terminals are tight and have a decent contact/grip of the all conductors (wires) and that no wire “whiskers” are poking out where they shouldn’t. See the section below on testing for electrical safety.
Mechanical Parts Check
Even modern conventional fixtures are pretty uncomplicated. Check all the moving parts such as lens and lamp tray adjustment, lock off handles,yoke and shutters. Anything that needs unjamming and lubricating, a squirt of PTFE spray or powdered graphite should do the trick – they are dry lubricants for use with high temperatures. Don’t be tempted to use oils like WD40 for lubrication You can use it as a rust treatment/penetrating oil but it will need to be thoroughly cleaned off afterwards.
Optical settings of equipment is usually set at manufacture. Just check out that the lenses sit straight in their holders, shutter blades have no nicks in the edge etc. As well as adjustment of the lamp tray, some lamp holders have a height adjustment set by screws and counteracting springs. Again, it’s pretty unlikely that the setting needs adjustment but the goal of height adjustment is align the lamp filaments with the centre of the reflector.
If you are based in the UK, all portable appliances must be tested/certificated for electrical safety. The Portable Appliance Test (PAT) applies to stage lighting fixtures too. Electrical tests are beyond the scope of this article and should be carried out by a competent person. However, a large number of equipment failures to pass the PAT are down to poor physical maintenance and can be traced by a visual inspection. Before the PAT regulations came into force, most theatres performed simple electrical and visual checks on lighting kit that did a decent job at testing for electrical safety. Now we have magic PAT machines which sit idly on the bench, while we carry out the visual.
You’ve looked at cable, plugs, lampholders, cord grips and insulation. At least you can send the kit of to be PATed knowing that you’ve done everything possible.
Hang it up again
So, we’ve got shiny, working lanterns with more light coming out the front. Maintaining conventional lighting fixtures is a simple but effective way of keeping your rig working better for longer. It’s not quite as much fun as drooling over the ShineyLites ™ catalogue but sometimes old kit just needs is a bit of lurve. Time for a cup of tea – mine’s "lampie standard" (white with two).
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