All of my pieces are color changing,and yeah the resin can build up quite fast if you let it. I try and find pipes with the holes of a large diameter,it makes them much easier to clean and they smoke better.Alcohol still works fine.I have about 15 pieces in the collection now.:thumbsup: In fact if you can ever get your hands on a piece from chameleon glass they clean out super easy with just warm water out of the tap each and everytime,its quite amazing(I recommend the vortex).