Just call ’em the dusty twins
Blocking is a technique where a length of sandpaper is wrapped around a semi-flexible plastic block. The block causes the sandpaper to really dig into high areas while skimming lightly over low areas until the entire car is smooth and even.
This is second blocking of this car … the first being after the application of the high solids primer used to fill any smooth and slight deformations in the sheet metal. This blocking is done with a finer grit of sandpaper after the urethane primer is applied, used to fill and smooth the sanding marks left by the high builds blocking, and further smooth the surface so the paint can be laid down absolutely smooth.
The second photo shows the car in the blocking process. It is a dusty process and by the time the guys were done they were so covered in sanding dust they looked like they had been ridding a 100 miles on horseback in the desert.
The last three photos shows the car, fully blocked and mostly cleaned up, in the booth. The car will be thoroughly cleaned then masked to protect it from over-spray. But for all practicable purposes, the car is ready to paint.
The we can start blocking on it again.