UV Fluorescent Ink Process Control

[ljgoldberg]

Regarding "invisible inks" that are not normally visible on the finished sheet, but which glow brightly under 365, 280, or 254 nanometer UV irradiation.
For the printers that use these inks for anti-counterfeiting, brand protection, or other purposes, how do you control the printing process to assure a readable or scanable image?
How do you assure sufficient coverage? How do you prevent over-deposition, wasting expensive materials?
How do you check image placement on web presses such as flexo label presses?
This is, of course a loaded question. Please wait for the other shoe to drop.

Thanks,
Larry

 

[Cornishpastythighs]

Stupid answer as I know nothing about UV irradation but why dont you install some of those bulbs in a booth at the press so the press guy can 'see' what he is printing.

 

[ljgoldberg]

"Good answer!" as they say on Family Feud.
Q: Why don't they install 6000K fluorescent lamps in the press room so they can see the yellow dots better?
A: Because there are better ways to see and measure yellow dots; densitometers, Beta Color Viewer, etc.

Hint #1: Measure -> Analyze -> Process Control...
Hint #2: How can you see an image on a moving web?

Thanks Cornishpastythighs

 

[dabob]

Since installing the light source that makes them visible is not a solution . . . I would talk to your ink supplier about how to institute "Process Control" . . . . from my perspective Cornishpastythighs had a pretty good suggestion

 

[ljgoldberg]

There exists a series of instruments that MEASURE the intensity and colorimetric coordinates of the fluorescence produced by UV LEDS at 365nm, 280nm, and 254nm.
​If the ink is known to be correct and authentic, and the objective is only to verify that an inkjet is not clogged or an anilox roll needs cleaning, then measuring the INTENSITY of the color signal in the appropriate channel is sufficient. Think of it as a densitometer.

If the problem is more serious or complicated, such as verifying that a security item is not a counterfeit, then measuring the L*a*b* properties of the fluorescence is required. With the capture of this data a color difference can be calculated and a tolerance applied. Think of it as a colorimeter.

Details of the system can be seen on our website;
http://betascreen.net/collections/b...rs-6/products/fluo-invisible-ink-densitometer

There, I've dropped the other shoe, gotten two people to think about a new idea, and hopefully avoided the boot.

Hint #2 still stands. Use a stroboscope to view a moving web to evaluate visible attributes such as alignment, coverage, etc. of a visible image. This is SOP in the label industry.
How do you verify the proper location of a security mark or image printed with UV fluorescent invisible ink on a moving web?

Thanks,
Larry

 

[dabob]

Seems to me you got it all figured out . . .

 

[ljgoldberg]

I was hoping it would be interesting or useful to someone ELSE as well.

We showed this at the recent DRUPA exposition in Dusseldorf. It seemed like EVERY banknote printer, security system vendor, ink supplier, etc. stopped by to visit and ask questions.
We showed this at the last DRUPA four years ago. No-one knew or cared what we were talking about.
I visited the famous Swiss SICPA company at that show. They gave me a Swiss chocolate and escorted me out.

Stroboscope is the answer to Hint #2. White light stroboscope for visible print, UV stroboscope for invisible UV fluorescent ink.
http://betascreen.net/products/beta-blink

I'll try my luck at FlexoGlobal where there are more rubberstamp printers.
Thanks

 

[dabob]

Ahhhhhh . . . marketing disguised as a 2 part question . . . . well played