Designing a "VOID" type background

[MassMacGuy]

I have a client who wants some gift certificates designed and wants there logo and/or the words VOID to be very faint but show up when copied like if you try to copy a check.

Is there some type of science to this?

My thinking and how I have it right now is the background is an 8% screen of PMS 300, the logo thing is over that at 12%. You can faintly make out the visual difference on a hard copy proof, and when I copy it, you do see these things popping out which is what they want, but not as drastic as I was hoping for like when you copy a check.

So is it something to do with the physical dot pattern itself? And if so how should I best design something like this?

I'm just using Indesign, does Photoshop need to be used as well to do something to this logo/Void part?

If anyone has ever had to design something similar, please share any info you might have that would help. Thanks