I've not soak almost any stamps since I re-start philately as there're many off-paper stamps on sale on the stamp market, however sometims I have to do soak for example when I found some of Thurn&taxis mint block are sticked to the other block or when I found Japanese old stamps with ugly backside with hinge or old papers.
So whenever I try soaking, I'm very serious because I do it with not cheap stamp but with stamps valued around $10 and more.
The shown is Japanese telegraph stamp 15 sen issued in 1885. which was with dirty backside before the soaking. It was in bad condition, however I'd like to hold it to check the manufacturing point. Yes I got interested in Japanese etched stamps recently.