Thursday, July 17, 2008

Wet Sanding and Polishing

Its now been over a month since spraying the last coat of lacquer. At this point the lacquer is nice and glossy but upon close inspection it has the typical bumpy "orange peel" texture on the surface. The process of wet sanding and polishing will render a glassy smooth "piano finish." I started with 800 grit on the 4th of July and worked to knock down the orange peel until the body was a flat matte surface void of any shiny areas. This took about 4 hours in total, most likely because I was checking my progress more often than necessary.

Here's a picture of my wetsanding setup:

I followed the Basic Finishing instructions (ReRanch 101) under "Final Polishing" with the following exceptions. Most of these items were suggested by experienced ReRanch forum members.
  • For the recommended pre-soak of the sandpaper, I first pre-cut each sheet into pieces that fit the my sanding block (eraser) and then put each set of grits in a separate glass of water to soak overnight. I labeled the glasses to keep track of the grits. I left the yet-to-be used sandpaper in the glasses for several days until I was finished with the wet sanding.

  • I used a pink pearl eraser as my sanding block.

  • I put plumber's putty in all of the pick guard screw holes, bridge stud holes, neck screw holes, and strap screw holes to prevent water from getting in and expanding the wood.

  • For sanding, I used a bowl of water with a few drops of dish soap. I'd take a fresh piece of paper from the pre-soak glasses and dip it in this bowl of water.

  • I tried not to sand too dry, always dipping the paper/eraser in the bowl to clean the paper and pick up more water, but I tried not to go too overboard getting water everywhere.

  • I checked my progress often by wiping the slurry off with a clean paper towel or rag.

  • I changed the water in the bowl often -- always between grits and sometimes during grits, especially with my starting grit of 800. It took me 4 hours to knock down the orange peel and get rid of all the pinpoint shiny spots. Maybe if I had started with 600 or 400 grit I could have gotten through the orange peel faster. I spent just over an hour each on the other grits.

  • I wiped the body down with naptha and a clean rag between each grit.

  • I sanded with small circular strokes with 800, but then switched to straight back and forth strokes for the other grits, alternating directions with each grit, and finished sanding with the grain at grit 2000.

  • Skipped 1200 because I wanted to finish faster.

As wet sanding progressed, the body got shinier. Here's a picture showing the contrast between the 1500 grit results on the left, and the 2000 grit results on the right. The bright reflection is from the under-the-counter florescent light fixture.

After wet sanding and before the polishing step I was removing the plumber's putty from the various screw holes and managed to pull a chip of lacquer away from the edge of one of the bridge stud holes. I also noticed that the holes had narrowed somewhat from the buildup of lacquer at the edge of the holes. The Carvin instructions say to use a hammer to pound in the studs, and I was worried about doing even more damage to the lacquer during that step.

Based on feedback from the ReRanch forum users, I fixed the lacquer buildup by sanding up and down in the hole with a piece of rolled up sandpaper. Afterwards the edge of the hole didn't look so good, so I applied some leftover dye mixture that I still had on hand from my experiments back in April, and then used a toothpick to apply lacquer to the hole edge . After it dried I lightly wet sanded the areas around the hole again with 1000, 1500 and 2000.

At this point I wanted to see what it would look like polished, so I used a rag and the 3M Finesse-It II compound to hand polish a section on the rear of the body. You can clearly see the reflection of the florescent light fixture here.

Hand polishing is a lot of effort so I did as much as possible with a Stew Mac foam polishing pad in my electric drill, and then finished up by hand polishing the inside of the horns.

Here are the results:

1 comment:

Epsolon said...

Just thought I should leave a comment, you're doing a splendid job with your guitar, I have read your blog and think you're pretty cool!

Just fyi...

hah keep up the work man.