Laser Tattoo Removal: If there was no frosting after treatment does this indicate the ink didn't respond to the laser?

Yes, frosting is typically a good sign of an effective treatment.  The frosting in tattoo removal is more evident in the initial few treatments.  With subsequent treatments, there is less pigment to treat, therefore you have experience less frosting.

Frosting can occur and is the collateral skin injury via protein denaturation and semingly is less evident with subsequent treatments. It is OK to continue your tattoo laser clearance sessions. 

Great question! I recommend learning more about
the Picosure laser for permanent tattoo removal. The Picosure laser will
permanently remove your tattoo without causing harm to the surrounding tissue
within fewer treatments than ordinary lasers. Consult with your doctor about
the new Picosure laser.