The rough / printable side is not difficult to find:
1x hold up to the light -> you can see the rough surface
1x over swipe -> done! The rough side it shows quite well, it's almost a little sticky!
Printed with a normal Canon printer (ink) - put on plain paper - standard printing speed - great result!
There is nothing smeared (contrary to my expectations) and the ink is bombproof!
For colored elements sometimes are small "dropouts" to recognize that were not 100% printed throughout. But is easy to fix with a different printer setting. (Adjust for better color images photo print)
Conclusion: Do not confuse the bad feedback ... it was my first film print and it worked immediately. This was honestly the reason why I rezensiere here. The euphoria about the unexpected success! : D