Several years ago, I bought a booklet that had a warning listed on it that if you tried to duplicate the pages with a copier or scanner, the bright light would fade the print and make it unreadable. This was to keep people from duplicating the booklet and selling or distributing it themselves. It also warned that the book should not be left open in bright sunlight for very long for the same reason.
I don’t know whether it was the ink or the paper that was special, and I never tried to deliberately fade the print.
Does anyone know how this was done and whether this ink or paper can be used in a standard inkjet printer? I got the impression that the process must have been fairly cheap or it wouldn’t have been used for this booklet. Does anyone know what this was?
Sounds like subterfuge to me.
It’s easy to make print that’s hard to copy, but the light in a photocopy machine isn’t all that bright - I have a hard time believing that a book printed with any ink that would fade that fast would be very useful.
Still, it kept you from copying it, didn’t it?
Possibly heat sensitive paper like ticketmaster (used to?) uses. I left some tickets in my car and within a month they were almost illegiblly black like the printing.
Most likely it was a photosensitive paper similar to something I have seen used for visitor’s badges at an elementary school. It was a stick-on label that had a space for a name to be written in and a solid color background. If you went out in the sun for more than a minute or two, the background faded out to leave a striped background to indicate that the badge had been taken out of the school. I think these were UV sensitive, but it’s the same principle as the booklet.
Actually, it was a book about super carburetors and high gas mileage. It has been quite a few years now, but I’m sure I have it around here somewhere.
The guy that put the book together was typical of a lot of people in this market and believed that the feds and gas companies were out to get him and everybody was trying to rip him off. He believed that he was loosing a lot of revenue because people were copying his booklet and distributing it for free somewhere. This was before the internet was in every household and doing something like this was easy.
I never tested the warning, but always wondered about it.
Glass blocks about 85% of UV radiation, so you’d have to be seated near a window during a long lecture. It could happen, but it wouldn’t be as fast as walking into direct sunlight. Similarly, clouds don’t block very much UV – the worst sunburn I ever got was on an overcast June day where it felt cool outside, but above the clouds was a brilliant summer day, and the UV shot right through.
Got my worst sunburn in fog. The funny thing is that it isn’t like a normal sunburn where the burn takes the pattern light would in falling on you - you know, most prominent on your nose, not at all under your chin. When you get a fog-burn you get a sunburn on every exposed piece of skin.
I’ve only been to that school about a half dozen times, so I don’t have a lot of experience with their badges, but at least once, I noticed that the background was only partially faded. I think it was cold and I had a coat on over the badge most of the time. So this illustrates how easy it is to fool this system if you know about it. Just keep the thing covered up outside.
