( I only used 350/450/700/1000 grit on my valves , if they fail the pressure test I will disassemble them & continue with the 1500/2000/3000/4000 grit . Let’s hope I don’t have to do that …..
grit sizes starting from left to right
60,000
30,000
15,000
12,000
10,000
6,000
4,000
3,000
2,000
1,500
1000
700
450
350