I use tempera paints for detail wash. It's very likely you're talking about my article which appeared in FSM a while back. Just add about 10% water, mix well, and you're good to go. Some folks add a few drops of dish detergent, but I haven't noticed any real advantage with it, personally. If it's lifting out completely when you wipe, it's possible that your wipe rag is a bit too moist, this is usually the cause. The next culprit is usually shallow panel lines. If the recessed lines are quite shallow, go very lightly with the wipe rag. You may have to follow up with a second and third tempera application to get it just right. I rarely have this problem with a Tamiya kit, since their recessed lines are usually deep and consistent.