When I remove pine tree sap I can hear the clay clicking & ticking as it hits the spots or any other surface contaminants. As the sap goes away the clicking diminishes to silence when you glide the bar over a lubricated, contaminant free surface.
Just take your time...
Good luck.

 

Unfortunately, I'm going to have to put this on hold and wash the car when I get back and move into my new house.

 

No worries, we're here or at the Cafe 24/7