Like Nicanor, I once contacted Lane #1 to try to find out the out-of-the-box surface grit on one of their balls and was told that since Brunswick makes the balls for them, they really don't know what the exact surface is. I also found that amazing. It seems to me that Lane #1 could either specify a certain grit surface for their stuff, or at the very least, find out from Brunswick what it is. I don't know why it is, but getting any kind of accurate information from anyone in the bowling industry, from manufacturers to bowling centers is nearly impossible. This leads conveniently to the next topic...
No one seems to know for sure what grit level you get from Liquid Sandpaper, but the generally accepted figure here on the board seems to be about 600 grit. Some folks have professed that 600 seems a bit coarser than what they see, and have mentioned that maybe you get 600 on a spinner, but more like 1000 by hand. I'm pretty sure, though, that you don't get 400 grit from Liquid Sandpaper. I've used Liquid Sandpaper, but not lately. My personal guess is that it gives you somewhere in the 800-1000 range. If you want 400 grit from a polish rather than scuff pads or sandpaper, the Ebonite Sand Blaster polish claims to give you a 400 grit finish. I have some, but haven't used any yet. Maybe we can get an opinion from someone who has used it. My personal favorite polish is the now defunct Ebonite Powerhouse Quicksand, which gets you to about 1200. An email I received from Ebonite tells me that the Quicksand has been closely replaced by Matte Finish--something else I haven't yet tried, since I stocked up on Quicksand.
Shiv