I'm watching Lynn's video where he's doing circles for dechipping razors, and I was amazed at how fast his 4k was pulling steel off the razor. I've done this same procedure several times on ebay razors, and my 4k doesn't cut nearly as quickly as his, he's getting as much metal after 20 circles as I would get after 100. The 8k will get black quickly, and the shapton does too, but the norton 4k side doesn't.

I think I now know why pyramids never worked for squat for me :-(