I can understand your desire for the appearance of the tank. However, you are not supposed to and should not remove any metal for it will condemn the cylinder. Polishing removes metal; albeit a small amount. Aside from this the very real fact that you could end up with a very big liability if the tank goes K-boom.
For example:
I wanted shot blast finish on my Luxfer bailout cylinders. They weren't made for several years by Luxfer. I was tipped off to where some were located. They were going to be a bit spendy to ship. So, I called Luxfer and talked to them about getting a normal brushed finish pair sent for shot blasting. I was advised very strongly against doing that. Each particular tank with its finish has a specific tolerance when made. The shot blast finish are slightly thicker to begin with to
accomodate the shot blast technique because it removes metal. For the end user to remove metal after the cylinder leaves the factory will condemn the cylinder.
I later learned more about cylinders, safety, and in particular removing metal, from the PSI Cylinder Inspector course. I'd highly recommend it if you can take it. You'll learn the facts and be able to weed out the myths.
The other thing is coatings stink. They don't last long. They get chipped and scratched. They typically end up causing more problems down the road when the water gets behind the coating, unknown to you, and rusts away the metal. Go with a bare cylinder. It's the "in" thing.
If you want steel, get the hot dipped cylinders.
