Quite a lot of guys wonder if there is a kind of invisible ink that they can mark the cards for contact lenses themselves.
YES of course. Our company supply the invisible ink, as well as infrared contact lenses, that can help you to try marking playing card for marked cards reader. And usually our invisible ink are sell and ship in pens, they are invisible ink pens. These pens can hold as much as 10 ml ink and very convenient to write or mark on back of playing cards.
How to mark and how long to mark or dry the marks? You can just see my video about invisible pen. You can see exactly how I mark the invisible marks with the luminous ink pens.
The invisible ink can mark both paper cards and plastic cards. Such convenient magic ink pens, try it immediately!