How often should I change the lights in my exposure unit?
With the number of different exposure units and light sources, there isn’t a clear-cut answer. I did reach out to a couple of experts in the industry to get some opinions. Here's a summary:
Fluorescent tube lights
You'll find these in a lot of beginner model exposure units. While they aren’t the best light source to use they will get the job done when you are starting out. Most manufacturers recommend changing out the bulbs every six to 12 months depending on usage.
Until recently, the long-held standard has been the single point exposure units, which uses an array of different lamps that could include metal-halide, quartz, mercury-vapor, or halogen, among others. These bulbs last varying time but something to consider is that the lamp will incur the most wear and tear in the start-up and cool down process. Some units have features that allow the bulbs to stay “warmed up” between exposures reducing the stress on the bulbs and giving them a little bit of a longer life than a bulb that turns off between each exposure.
A general rule of thumb is to change the bulb every six months or 500 exposure hours, whichever comes first. Again these are very general guidelines, and every unit and light source are going to differ. My advice would be to do an exposure test on a regular basis and track your results. After collecting some data, you should be able to create a guideline based on your particular unit.
Ah, the new kid on the block! LED units have soared in popularity lately due to their quick exposure times, energy efficiency, and long-lasting life of the bulbs. There’s a lot of debate into whether LED is actually superior to previously mentioned light sources, and I’ll refrain in getting into that here. As far as the lifespan of the bulbs or how often to change them it’s honestly too early to tell with this tech. Some manufacturers go as far as to claim that they will last as long as the unit will turn on. Again, it’s too early to tell, but I’d advise doing consistent exposure testing to ensure your stencils are coming out the best they can.