Hi,
I have had NBUVB twice. The first time (2008) was a success and I was clear for about 9 months. I think that it was after about 12 treatments that I really started to notice a difference.
The second experience (2010) was not good at all, so I won't dwell on that.
It sounds like most of you P is guttate, but if it is plaque, then you need to moisturise or the light won't get to the skin. Moisturising should not be a problem if you don't use something that is high in paraffin, or reflective. Perhaps a good move would be to do it overnight.
Regards,
Daryl