I had tried on few deck with different methods and same results. After few seconds, even if you put it on both cards(face on a card and back for the other, it doesn’t stay together. Better than that, a wax candle will be more efficient

This roughing balm is not to bad at all. I have had some good success in using it.

Keeps cards together well, but is much more noticeable on card surfaces in the right light than the Harry Robson roughing stick.

It is a tool which can be very convenient to use in case of Roughing.It is less sticky than a Roughing Stick, so it is easy to use, and it is in a Lip Balm Container, so it is great for keeping clean and carrying. And most of all, the noise from separating the roughed cards is less than the Roughing Stick.Of course, the Roughing works very well. If you enjoy card magic, we recommend at least one. However, the information written by Laurent Garcini just below is not true.In case of using candles, it is not possible to do Roughing properly. And Roughing Balm is much more effective than candles. But I really do not understand why there was such a bad assessment like comment.I guess it was made only on one side of the card when performing Roughing the card.
(Both cards must be Roughed on the side where they are contacting each other.)

The tutorial is in Chinese!!!

I received a Bicycle Invisible deck at the same time as this roughing balm, and despite very light handling, about six of the R&S pairs would not stay together when fanning. The Neo V2 came in very handy for a touch-up, to make the Invis deck useful. The negative, for which I subtract a star, was that using it with moderate pressure in a stripe down the center of the touching backs of each matched pair did not have any effect, nor did doing so all over the cards. Pressing harder also had no effect. Rather, I had to press EXTREMELY hard and go over each card multiple times in a larger area than I had expected before they would reliably stay together when fanning. It was successful at that point, but required much more pressure than I had expected or would prefer. Thus, the formulation seems to me to be a bit too hard, at least for the one I received, and it was less convenient to use than I'd expected. I'd prefer that it transfer to the card with less pressure. But it does work well, in the end.