I worked with a guy in the 80's who had a side business making diamond grinding compounds for customers in the bay area - he would pre-load his secret mixture into grease-guns he bought at Sears. They were single use, he told me. I don't remember why, something about screwing up the seals, or maybe a used grease gun put contaminates in the grinding goop... anyhow he made really good money at it for some reason, there must have been more to it than meets the eye. He was a retired nuclear physicist, so he knew what he was doing, when it came to small particles.