Security Printing

[RickS]

A salesman came in with a sample he was bidding on and wanted to know if we could do it. The sample has a screened background, but when copied on copy machine, "Void" shows up. With a loop, the word void is a higher line screen than the rest of the background. Is this created from some special software that we could purchase? Screening is done at the last step in our plating workflow. We are on the Nexus PDF workflow if that helps. Any ideas?

 

[Vytas]

This does not answer your "Void" question but there is a security printing algorithm that you can print that allows you to lay down 20-30 micron dots that are invisible to the naked eye, that are encrypted and can only be read with a WiFi pen with encrypted software. Depends on what the intention is on the securely printed document.

 

[RickS]

The intention is the printed piece could not be copied on a color copier without something showing up that didn't appear on the original. Your Idea does give me an idea I can try to do something with. Any other ideas? anybody?

 

[Stephen Marsh]

Rick, there are two ways that is this done that I know of:

i) Use a very fine "line" halftone screen for the void (rules, not halftone dots), with the background being lower screen ruling.

ii) The second easier method is, as you say, uses two regular halftone dot screens at different LPI for the same tint value. I can't recall if the screen angles are different, as well as the LPI.

Off the top of my head you will need to explore two general areas to achieve this. One is to use a raster EPS image for the void and to embed a custom halftone screen ruling into this image. Next your workflow would need to honour this custom halftone info and not strip it out and then be able to image the two different dots.

If you have not done this work before, it may become costly to produce, as you will have to get things correct on plate, then press and finally photocopy the end product to see if all works as intended.

I did my apprenticeship in security printing and we sometimes did this on the Purup proprietary prepress system that I used to use 20+ years ago - however I have not done this in the PostScript/PDF age...

Good luck and please keep us posted!


Stephen Marsh

 

[jlind]

Security Printing.

Security Printing.

I think there are patents concerning the VOID Pantograph use, and you may need a license to use/do it. I would look at Standard Register, but there may be others. But you are right about how it's done

 

[pcmodem]

If you have Nexus Edit. I believe you can apply a different screening to certain elements. I never used it but I remember something along those lines from class 10 years ago.

 

[DavidMa]

We do Void Panto here. We had to have a special image file made for our specific output res, line screen, and the press it runs on. I can't recall the company that set it up, but it took some time and a press test to get the right image to work. It usually prints in black only and as as sep color from the process black.

 

[RickS]

Now that sounds like a way to go if you know the company.

 

[rotarypower3]

I make my own using 2 different screen rulings. You've also got to get the percentages right, plus you can only use certain PMS colors. They usually have to contain a high amount of black.


..

 

[Stephen Marsh]

I make my own using 2 different screen rulings. You've also got to get the percentages right, plus you can only use certain PMS colors. They usually have to contain a high amount of black.


..

Would you mind going into more detail rotarypower3?

What screen rulings do you use? How far apart are the two screens? Say 175lpi for the background and 150lpi for the void text?

What tint values do you use, how far apart are the two tints?

Are they both imaged at the same angle?

I understand that this will be press and substrate specific, however as an intellectual exercise it is good to know the sort of variance required.


Cheers,

Stephen Marsh