When hand sanding with 320grit or higher, you really aren't removing much metal. As you know, it takes quite a bit of sanding just to remove the previous grit scratches. The one thing you can do is round square edges if you aren't careful. However, if you have swoopy plunge lines (the way I make mine) it is hard to get those scratches out of the swoop. This is where a leather backer is worth its weight in gold. I put a lot of emphasis on the corner of the leather so that the sandpaper is working off the corner and I can really get in there and rock back and forth. On the flats, the leather really pays off because the sandpaper bites and it will reduce your sanding time by at least 50%. It's that dramatic. Just be careful around transition or lines you don't want to round off / smooth out. That's when I drop the leather backer and go to the doubled up sandpaper.
Nick Wheeler's vids are awesome. I don't glue my leather to the sanding stick, though. It wears out, so I never saw the point. The sandpaper going around it holds the leather in place well enough for my needs.
BTW, it doesn't have to be leather. I use leather because I have loads of leather scrap laying around and it works. Anything that is rather stiff but has some tiny bit of give will work fine. Hard rubber would work, too. A strip of wood like a paint stick would probably work great, too. I know when you're just starting out you don't have tons of scrap anything laying around. A year from now you'll have buckets full of scraps to choose from.
For my sanding stick, I have a piece of 1 inch x 1/4" brass, about a foot long. Why do I use that? It was scrap. I bought it way back when to make guards out of. I made one brass guard and never used it again, so there is was. I'd be better off with a hardened piece of steel, but I'm so used to it that I keep using it. When it takes a little bow ever few months I straighten it back out. So I'm living proof that you can learn to use substandard crap once you know how it acts, LOL.
another tip: I don't know if you've learned this yet, either. Mobil 1 synthetic motor oil for your hand sanding. Yes- it's that different. Yes- it works that much better. Yes-get some. Like everyone else I'd tried everything under the sun: windex, wd40, regular motor oil... Mobil 1 synthetic is freaking magical. I use 5w-30 or 0w-30. I started running it in my cars, too, after seeing how well it suspends metal particles during hand sanding.
