Marked cards have probably been around for as long as playing cards have been used for gambling. In fact, the first marked cards were likely to be unintentionally marked by their makers, as the first playing cards were hand made and thus subject to inconsistencies. But as playing cards evolved through history so did methods of marking them for the purposes of cheating. In our time there have been many ingenious ways of marking cards and as time goes on there will undoubtedly be more ways to do it.
Since there is no single source for information on marked cards and since there's always been a great deal of secrecy to protect the "recipes," as card cheats would say, it takes a little legwork to get the information. Also, since playing card manufacturers continue to change the methods of producing playing cards, continued research and development is needed for those of us that wish to stay up to date with all the latest information. Some of the old recipes might have worked great in the 1960s, but doe to some of the changes in playing cards there is no guarantee that the old recipes will still work. In fact, some old recipes are totally outdated and have become useless.
I have spent a great deal of time and money researching various ways of marking cards. Here is just a small portion of some of the substances I've experimented with, through the years. Most of the substances I've tested did not produce satisfactory results, but I still decided to keep it all stored away in boxes. After all, I've paid for all that stuff.
The selection of vials you see on this photo just came from one box, from a specific time period. I have a lot more than that stashed away, but at this time I don't particularly feel like digging through my old stuff just to take a picture for a blog post. What's important is that every vial is labeled and there are written records kept of all the experiments.
The next photo shows a selection of test cards I've marked, labeled and stored away. Again, that's just a small sample that shows test cards I've actually placed into binders.
The important thing about these archived samples is the labeling. I need to know when the sample was made, what substance was used and I also need to reference any additional written records I might have kept about any particular sample.
I wish to emphasize that the date is very important. What most people don't realize is that the work you put on the back of a playing card today might not look the same tomorrow, or in a week's time, or a month later. Some chemicals used in dyes and solvents will have a delayed reaction against the finish of the playing cards, when exposed to air or changes in temperature and humidity. So, some of the work that might look invisible today might look like a yellow trace after some time has passed. To avoid such undesirable results I always test my work over time, by keeping labeled samples and meticulous records.
Naturally, I've learned a lot from my own mistakes. I wasn't always quite as organized and I had my share of surprises, when I looked back at some of the test cards I had kept. At some point it became obvious that the only way to do it is to adopt the science lab approach and keep records of all the experiments.
Lastly, in addition to all the test cards I've kept I also have a binder with all the best work that I've produced and collected. The binder has samples of various types of marked cards, along with written descriptions. The descriptions do not have recipes, since this is more of a sample catalog that I often use to show around.
For further information on marked cards, please visit the marked cards chapter on my main site, as well as the marked cards tag on this blog.