I haven't tried a full body soak of an R card
. That being said I have always used warm water and a Q-tip to get off paste remnants, from almost any surface, and as long as I don't rub it too hard, or for too long, have always had good luck. This is what I would try first anyway. There is almost no liability in damaging the card imo...just do it lightly and be patient (not like I did a few times, where the freaking paper comes off). Good luck