So you’ve run the file around the edges and it is looking much “flatter” than after the RT (Rotary Tool). Next it is time to sand the edges with at least two progressively finer foam sanding blocks. We recommend starting with a 120 grit sanding block. You can use as much or as little pressure as you need, just keep in mind that if you have already installed your eyelets or hardware you want to make sure the sanding block does not come in contact with the hardware.
The foam block will conform to the contour of the edge as you press on it. You can also push the block into the acute corners and really smooth them out. Once you’ve gone over the entire outside edge, start over with the next finer grit sanding block. We’d recommend 180 grit or more.
You can repeat this process again with ever finer grit blocks, but 180-220 is about as fine as you’ll need to go. Now it is time to “buff” your edges.
To “buff” the edges, you’re going to rub a cotton or synthetic fabric vigorously along the edges. What this will do is slightly melt the surface from the friction and give you that mirror edge finish. We’ve tried all sorts of rags for this job, but for whatever reason the absolute best material we’ve found is the old-time Nomex Flight Gloves. The synthetic blend is just right and will give you an amazing polish on the edges of your Kydex.
So that is it. The No-Buff, High Polish edge for the DIY enthusiast. Here's a quick edge comparison.