Shave before treatment and I suggest microsecond yag laser treatment for best outcomes with little risk. Best, Dr. Emer.
While I am not familiar with this particular laser, I can say that you should definitely not have blisters nor should you have red marks that don't go away for several days. At my practice we use the GentleMax Pro for hair removal with very good results. It is typical for treated areas to be red and appear like goosebumps (never blisters) post treatment, however this should subside over a 24-hour period. We always shave hair prior to being treated for two reasons: first being that the energy of laser needs to be directed to the growth center of hair to be most effective and if the hair is long, much of the laser's energy will be wasted; second since the laser will focus some of its energy on the long hair, the skin beneath that hair can be burned creating problems such as blisters and hyper/hypopigmentation. All of this is not meant to scare you, only to inform you and urge you to discuss the procedure with your hair removal provider, as your well-being should be your biggest consideration.