Wet sanding, polishing, shielding, and a gouge!

It is advised to wait a month before starting to sand, because that’s how long it takes lacquer to reach its practical hardness. I didn’t have the patience for that, so I started wet sanding after three weeks (as I mentioned in my last post). Here’s what the guitar looked like prior to sanding:

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I started by filling all the holes, with the exception of the neck pocket holes, with beeswax. The wax prevents water from going in them, swell the wood, and therefore make the lacquer above it crack. I held off on buying beeswax because any store that had it had just a tiny bit of it, and it seemed to be really hard to the point where I won’t be able to easily cut it and shape it. The size really isn’t a problem, because I think I can easily do 30 guitars with the small amount of beeswax that I got. As for its hardness, it is indeed hard, but I could cut a small piece with a knife, and then roll it in my fingers to make it fit the holes. I then cut the excess with a ruler or something, but I also discovered that if you sand the excess, it won’t mar the finish or anything. At best it clogged the sandpaper. Unfortunately, some holes weren’t 100% plugged, and water got in them and caused cracks. Next time I’ll use more wax, wipe off the guitar more often, and really just use the water to clean the sand paper. For what it’s worth, though, the cracks were very thin, and I don’t see or notice them anymore.

Besides cracks, I also had to deal with sand throughs. I wrote in one of the last posts that I gave up on spraying clear over black and ended up spraying four coats of black over the five coats of clear I had on the body. I should explain why four. For “thin skin” finishes, it is recommended to spray 9 to 12 coats of clear over the color coats. I already had 5 coats of clear on and a very thick first coat of color, so I thought four (for an overall of 9ish final coats) should keep it thin. I also tested it before spraying and four coats were enough to not sand through. However, I think I started sanding through to the clear coats underneath a little bit. The only indication I have for sanding through is that the water (as I was sanding) wasn’t pure black like it did earlier in the sanding, it was a little diluted. Usually, sanding clear lacquer makes the water turn white, but I didn’t get that far. However, the sand throughs must be minimal, because I can’t see any discrepancies in the finish. Still, next time I’ll put on six final coats or more (if I don’t spray clear).

The sand throughs were a result of how long and hard I had to sand. Sanding took maybe 5-6 hours (if not more) starting with 800 grit all the way through 2000, and I had to press really hard to sand anything. This was probably the result of how long I waited to sand. For instance, the neck of this guitar I sanded five days after I finished spraying, and it required minimal effort to do. Next time I’ll wait five days, then test the lacquer by pressing with my nail at a hidden spot. If there’s no impression, I’ll wet sand, and then let it dry for 20 more days, then rub it with a compound and polish. The polishing can be done along with the wet sanding, but since it’ll hang to dry and collect dust, I prefer to polish last. Speaking of polishing, when I first started reading about how this is all done, I thought I’d need special material to rub on the compound and polish. So I bought a buffing pad and I’ve never used it. The reason I’m not using it is that I first wanted to practice wet sanding and polishing on a scrap piece of wood with lacquer, and I didn’t want to waste the buffing pad. For that, I used a white cotton t-shirt. The results looked great, so I stuck with it. It’s best to use an older t-shirt that has been washed a bunch of times. This way it has less lint. The compound and polish I use are Meguiar’s Ultimate Compound followed by Meguiar’s Ultimate Polish (in this order).

Here’s the end result. It’s hard to take a picture of a black finish, because it really just acts as a mirror. I think the Meguiar’s products do a good job and make it look real shiny.

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Shielding the cavities is pretty easy and cheap, especially if you buy something like this (2016 EDIT: this tape isn’t conductive on the sticky side. It’s not a big deal when shielding body cavities, but it can be a problem in other instances), which is way cheaper than copper tape and is just as effective. Taping along the edges with one long piece is a no go. The way to do it is cut small pieces and overlap them. It’s really tough to get around the tight curves like the one at the bottom of the cavity (where the jack would sit). Here’s the body all shielded:

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And a few close-ups:

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I took a picture of the back when I took the pictures of the shielding, and that picture looks better than those I already posted. So why not show it off.

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Here are things that I learned for next time:

  • Don’t wait 30 days to sand (but do wait 30 days to put the hardware on, etc.), just five days or maybe a week.
  • Plug well with Beeswax and don’t let so much water get on the body.
  • It’s better to go thick and not thin skin than sanding through. I was lucky this time around, but might not be so lucky next time.

As for the gouge — too soon for me to talk about it. Too soon.

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