Corona Treater Indicator Light: ON or OFF?

Ever found a stack of printed rolls ruined because the corona treater wasn’t running? I’ve been there, and it’s not pretty.

My first flexo press was in line with a blown film extruder, producing newspaper bags, printed or unprinted. It was a non-stop process, with film feeding directly into the press and onto a turret rewinder. When I wasn’t printing, I was extruding unprinted film for any one of 36 bag machines. We stayed busy.

Corona treatment was crucial for printing, and I quickly learned the pain of walking into work to find rolls with ink that wouldn’t stick. Back then, treaters made a high-pitched "eeeeeeee" sound when running, and a light bulb at the extruder indicated whether they were on or off. Every press I've operated or seen since has some kind of treater indicator.

But here’s something interesting: some treaters have lights that indicate when the treater is running, while others use lights to warn when the treater is off. Which setup is better?

If the light signals the treater is on, a bulb going out prompts the operator to investigate whether the treater is off or the bulb just died. Either way, it's a signal to check. However, if the light warns only when the treater is off, a burnt-out bulb might go unnoticed, leaving you at risk of printing on untreated film. This is problematic.

For many of you, this seems obvious—you wire the light to show when the treater is on. But if it were universally understood, every system would be set up that way. Yet, not all of them are.

So, if you want to avoid quarantined rolls and ink that peels off with tape, make sure your light is set up to come on when the treater is on. It’s a simple step that can save a lot of trouble.

How are your treaters wired? Have you ever faced issues with corona treating? Share your thoughts or tips in the comments below.

Remember, the right setup can save you from a lot of headaches.  Happy printing!

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