As far as a blue head goes, I get that too because when the hanger bunches up the skin, internals, and wrap against the glans, some of the bunch goes over the edge of the glans, leaving just the tip of the glans exposed which eventually turns blue.
The blue is just trapped blood in the area and does go away after about 15 min after the hanging session. You’ll find it gets cold too. This and numbness are what you should closely monitor. You don’t want to feel any numbness or let it be cold too long. That’s why the heavy set should last only 20 min. I’ve gone to 25 min. with 14 lbs. which is my max - SD - with no problems, but normally I get a discomfort increasing in the glans at about the 20 min. mark and that’s when I stop.
If I drop the weight to 10 lbs., I can go 30 min. easily with no problem at all and to be honest - it feels better and safer. I can hang to fatigue without undue stress on the glans and only with slight blue discoloration.
( DAMN!! I’m sitting here at work ready to hang with my 10lb. laptop & case but I can’t because there are others here “just doing some extra work” as if they got nothing fucking better to do. Weekends alone here at work are my major hang days!! I can’t wait til they leave already! Maybe I should just kill them and get rid of the bodies. :D jk )