No, this is not about sanding hands. It’s about using your hands to sand.
There isn’t much new to say about hand sanding. The basics of sanding are very simple. Each progressively finer grit leaves scratches finer than it’s predecessor. Finer grits are used until the scratches left are no longer noticeable. In general one should always sand with the direction of the grain.
When sanding a flat surface a sanding block should be used. Curved or contoured blocks can be used for curves or special profiles. In some situations your fingers might be the perfect sanding block.
Sandpaper is a tool. As in using any tool the results will vary according to the knowledge and skill of the user.
I tend to avoid coarse grits when hand sanding. By using edge tools, rasps and files I usually don’t need to use anything more coarse than 150 grit. I use 150 grit paper “freehand” for heavily rounding, shaping and blending curved surfaces. Sometimes I back the paper with tape to give it a little more body.
I also use 150 grit with a sanding block for all flat surfaces. The scratch pattern left on the wood quickly shows me any high or low spots needing attention.
I follow 150 grit with 220 grit. Usually 220 grit is all that I need to prep for finishing. Some woods like maple and cherry might reveal fine scratches unless I go up to 320 grit.
At this stage I wipe down the instrument with a slightly dampened clean rag. This raises the grain a bit and I can then sand the resulting fuzz away. This step lessens any raising of the grain when finish is applied.
To check if sanding is complete I wipe down and vacuum off the piece. If it looks good I wipe it down with some alcohol. This gives me an idea of what the wood will look like when finished. Flaws in the prep work always show up much more after the finish is applied.
When sanding you will want to keep your nose clean. When raising a lot of dust wearing a dust mask is a good idea. Don’t wipe your eyes with dusty hands (ask me how I know….)