Can't stop getting blisters from vac hanging
So to preface I started vac hanging last year with the usual aliexpress cups and sleeves setup and they worked fine, managing daily 1-hour hanging sessions (weekends off, longer breaks during weeks I was more busy). My usual routine has been 10-15min in the bathmate, then 1hr of hanging at 10-15min intervals. I also lube the vacuum cup with coconut oil before going in and starting the hanging sessions.
I started with a ~3lbs weight when I first started, and went up to 5lbs pretty smoothly and went with that for a while. It was then in March of this year I decided to move up to ~7lbs where I then ended up with my first blister on the underside of my glans, and since then I've no longer been able to hang properly.
Without going through the details, even after spending 2-3 weeks recovering, lowering the weight or decreasing the time I still get a blister forming (always in the same spot as well)
At most I managed to have a 30min session without problems (after a second failed attempt, I lowered the weight after letting it heal again), but the reason I didn't go for a full hour was because during the next interval I felt a tingling sensation (one that I now associate to a blister forming) and managed to stop before the blister fully formed. It still developed a tiny bubble but that healed in a week, and it was then that I tried again but this time in the first 10min interval I developed a blister.
Is it because I developed a blister in the first place that its now easier to form? I'm not doing anything different that I can think of during the previous year compared to now, so that's the only thing I can think of now that I've failed to hang blister-free the past 3 attempts. I am thinking of attempting to use saran wrap once I heal again for my next attempt, but since that would be sometime in June once I fully heal again I thought I'd ask here for any additional tips.