The only negative trait of vacuum hanging is the potential for a blister. I too have experienced an annoying blister and it took me some time to figure out exactly what causes them and how to avoid them. So let's talk about what the main contributors are to creating a blister....
There are a variety of nuanced reasons for blisters, but the primary cause is trying to use too much weight or hang for too long of a time duration (or a combination of both) before you have developed the proper amount of skin conditioning. The meatus skin is very sensitive and delicate skin. Vacuum pressure is directly exerted upon this area, so it's vitally important to find the glans protection wrap method that works best for you. We have three methods, all of which are based upon a personal preference. I suggest you experiment to find which method best suits you.
The process required to achieve the skin conditioning that allows you to successfully hang is analogous to getting a sun tan or working with your hands. You wouldn't go out on the first day of summer and expose yourself to several hours of sun without getting burned. If you weren't accustomed to working with your hands and decided to chop some wood one weekend you'd likely get blisters on the palms of your hands. Maybe these aren't great analogies, but I think you understand the point I'm trying to make. So what is the best way to condition your meatus skin? The answer is to deliberately start with a light weight and hang time. In our instruction manual we have a suggested beginner routine. I started with only 3 lbs for 30 minutes, twice a day, one session in the morning and another session later in the afternoon or evening. It took me three full months of dedicated training 5-6 days per week to incrementally go from 3 lbs for 30 minutes up to 8 lbs for a full hour. For many men who already have a significant amount of PE training under their proverbial belt this initial beginner phase of conditioning seems to be too light, and the temptation to accelerate to heavier weight and longer hang sessions ends up being detrimental.
It's very important to gradually make small incremental increases in weight and time. I used a pyramid method and this is an example.... starting with 3 lbs for two 30 minute sessions per day. After a solid week with this weight and time I increased the hang time by another 10 minutes, then after another week 10 more minutes, until I was up to a full hour with no complications. Then I added two pounds, but dropped back down to 30 minutes and repeated the same process over again. Remember the two fold goal is to reach fatigue and develop skin conditioning. Going heavier and longer isn't a shortcut to greater / faster gains.
Now let me give you some inside baseball information on how to prevent a blister. There's a distinct sensation to be aware of during your hang session, and if you can tune into it you will prevent a blister. If at any time during your hang session you feel a slight itchy or tingly sensation on the tip of your penis then that's the red flag signal that you need to immediately stop your hang. If you ignore it or don't recognize it you will develop a blister. If you heed this advice you will be on the road to successful weight hanging that will manifest length and girth gains and help you avoid blisters!
If you stop your hang once you feel this sensation, remove your chamber and inspect your penis / meatus skin. If you see a very small blister forming, say the size of a BB, leave it alone. Usually the next day your body will have absorbed the little bit of fluid and the skin will have re-attached. If however the blister is larger, say the size of a pea then sterilize a needle, pop and drain it, but don't remove the skin! Apply some anti-biotic ointment like Polysporin or Neosporin and cover it with a small band aid to keep your clothing from rubbing against the area and aggravating it. Give it time to heal, usually 3 - 5 days depending on the severity and size of the blister. Begin to trim the dead skin away with some cosmetic scissors or a pair of fingernail clippers. During this healing time continue to do your hand stretching exercises. Do not pump or hang during the healing process. Bottom line.... live and learn. Once you resume your weight hang training you want to drop your hang weight and time by at least 50% while you recondition that new virgin skin. Then incrementally work back up to where you once were. The primary goal is to find a weight that you can successfully hang with for a full hour with no complications. Once you reach that goal then and only then should you think about adding more weight.
There's one more potential blister creator, and that's using too much vacuum pressure! Typically I recommend using as little vacuum pressure as needed. Remember this is not a penis pump! All you want is enough vacuum pressure to create a good seal between your penis skin and the silicon sleeve. The skin / sleeve seal is what allows the chamber to hold vacuum. If the integrity of that seal is compromised then you'll likely experience weight slippage, and most guys try and counter act that with more vacuum. I suggest as a guideline to use no more than 10 Hg's of vacuum pressure. I feel it's extremely important to have a hand pump that accurately indicates Hg pressure.
Making sure you properly maintain your silicon sleeve will go a long ways in preventing vacuum leaks and weight slippage. I recommend after 30 - 40 hours of training that you remove your sleeve from your chamber and wash it with warm / hot water and anti-bacterial dish soap. Blow dry it with a hair dryer or clean cotton towel (no paper towels - too much lint). This will help restore your rubber's sealing capabilities and tackiness, and also prolong the life of your rubber. Sleeves do wear out, but if properly cared for they should last a minimum of 4 months. If you start to experience weight slips due to vacuum leaks then it's time for a new rubber sleeve.
I hope this helps those of you who have experienced the set back of a blister! Just remember to be patient and think marathon and not sprint.
*You can also try some fulcrum and bundle exercises that don't require as much weight. The Fulcrum is where you hang your penis over a bar or rod that lies across your thighs (see photo). Link to Fulcrum Video: https://lghangerllc.blogspot.com/2016/04/kingsnake-folcrum-demonstration-lg.html
A bundle is where you twist your penis 1/2 to a full turn and hang with weight and not allow it to un-twist, and it can be done while using a fulcrum for even more isolated stress. We have a great video on bundle hanging: https://lghangerllc.blogspot.com/2017/12/tutorial-bundle-exercise-demonstrated.html