Sanding and Buffing Tips

I'm definitely not the most experienced finisher around, and thought it wise recently to undertake something of a personal refresher course by sifting through some relevant forums and Facebook groups with a view to improving the quality of my finishes. Here's a collection of thoughts on wet sanding and buffing that I've compiled:

• Invest in some good quality sandpaper, not cheap hardware store varieties. There are many good choices; 3M's Trizact is a trusted product, as are many of Mirka's papers.
• Depending on the quality of the final finish coat, begin sanding with the finest grade of sandpaper that will accomplish levelling of the surface. Most recently, I've started with P600, but will begin with P800 in future. Grits coarser than P600 are probably best avoided. 
• Keep your work area spotlessly clean to minimise opportunities for dust and other particulate matter to scratch the guitar as sanding and buffing progresses.
• Wrap sandpaper around a foam or cork block.
• Sand in straight lines rather than in a circular motion.
• Having completed sanding with each grit, put rags or paper towels that have been used to wipe away sanding slurry to one side for disposal or cleaning, then grab fresh ones.
• To more easily identify scratches remaining from the previous grit, sand in an opposing direction when progressing to the next grit.
• Before use, soak sandpaper in a container of water to which a few drops of dishwashing liquid have been added.
• Change the water used to wet the sandpaper when progressing to the next grit. Soak the paper before use, as before.
• As you wet sand, check the sandpaper frequently for any build-up of finish that could cause scratches.
• To guard against sanding through the finish, delay sanding of edges until the finer grades of sandpaper are in use.
• Assuming you have access to a buffing arbor, sand through the grades of paper up to at least P1500, although P2000 would perhaps be a better target. Some builders advocate even finer grades of paper, but the Law of Diminishing Returns perhaps applies in this context.
• When buffing, remove polish residue from the guitar surface frequently to allow the buffing wheel to contact the guitar surface rather than the polish residue, which can impede progress. Removal of the greasier buffing compounds can be difficult; a drop or two of swirl remover rubbed over the affected area, then removed with a clean, soft cloth seems to work well.
• Complete the polishing process with a liquid swirl remover, either by hand, or with a drill-mounted foam pad.
• Be patient!   

As I remarked in the first paragraph, I'm no expert, so if you disagree at all, or care to expand the list, please feel free to comment below.

I aim to experiment with dry sanding as an alternative approach shortly. Stay tuned for a blog post on that topic.

Cheers, Pete