An experiment with a guitar

My Chinese stratocaster

In January I bought a cheap stratocaster out of China to test whether that style of guitar is what I wanted to own. I hoped it would be good enough to help me figure out whether I liked the style, but expected it might not ever be able to be tuned properly. My plan was to replace it with a real one later on. However, it turned out to be a genuine fake Fender stratocaster, and was impressively good. In the absence of an actual strat and to the newbie guitarist you might believe it’s the real thing. It only needed some nicer strings and an adjustment to the intonation via the bridge to be playable (which admittedly might not be something a newbie would know to do). I was a little disappointed that it was branded, but it served its purpose: I quickly realised that this was indeed the type of electric guitar I wanted to own.

Fast forward to a few weeks ago: I decided it would be a good idea to try my hand at building a stratocaster instead of buying one. I thought it would be something that would keep me entertained for a bit, and I get something cool I can use at the end of it. Also, because I had been considering buying a “proper” electric for some time, adding another guitar to my collection was already on the cards.

Electric guitars can be reasonably simple: a Stratocaster (strat) or Telecaster (tele) are a block of shaped wood, a bolt on neck, some pickups, bridge, tuners and some basic electronics to make it all work. Each of these parts can be bought pre-made, and assembled into a full instrument. You can even buy kits that have all the parts ready to go. In retrospect, I probably should have started with one of those.

Instead, I decided to buy a nice unfinished body — basically a precut block of wood — and start there. It conveniently comes with all the relevant holes drilled and routed out, but hasn’t been sanded at all. All the edges are sharp, and even the rounded edges haven’t been smoothed. There are also ridges all over the front and back: it’s in no way a flat surface.

The first step after the body arrived was to get some supplies: sanding paper, masking tape, primer, colour coat and clear coat. This meant I upfront had to decide what colour I wanted my guitar to be. I had thought a nice shade of green would make a nice guitar, but the store only had “grass green” which was basically #00FF00 (that’s bright highlighter green for those not from the computer world), so on the spot decided to go for crimson instead.

I ended up spending almost a day — on and off — sanding the body by hand to my satisfaction. I was using 1200 grit sandpaper, and I think I should have started with something much rougher, got the ridges out, and then moved to a finer grit to smooth it out (we’ll see why I think this shortly). I also think I should have worn a dust mask. I was clever enough to do it outside, at least.

As an aside, using a sanding block works nicely for the flat surfaces, but is impossible for any of the edges. In fact, the cut out by the neck pocket (where the neck screws in) is impossible regardless. I believe professionals have a tool for this which is basically a cylinder with sandpaper glued on, and attached to a drill… but this project hardly justified purchasing such a thing. It might have saved some frustration though.

So, believing I had the guitar smooth, I set up a rig to hang the guitar whilst I sprayed it. I started with some fishing line wrapped around a tree branch and anchored to a small stepladder. The guitar body is reasonably heavy, and the ladder turned out to be too light, so I had to reconfigure it with a hose reel as the anchor. I surrounded it with lots of cardboard and newspaper to prevent spray paint getting everywhere.

Donning a dust mask, I started on the guitar with white primer. It didn’t take long to discover that I hadn’t got all the ridges after all. With spray paint, the paint catches and builds up against any edge. Also if there are any striations on the surface the paint will disappear into the gaps. I ended up doing a light coat and stopping because I realised I was probably going to end up sanding most of it off anyway.

The paint needs a minimum temperature to set (10 deg C) and 24 hours to cure. Unfortunately it’s winter in NZ at the moment: any spraying needs to be done about midday to set, so I can only spray on weekends. I did the initial spray on a Sunday, so had to wait a full week before I could respray after first had cured. I am not a patient person and this seemed like an eternity to me.

On the following weekend, it took another hour of sanding before I had convinced myself that I had got all the newly discovered ridges out. The striations would need to be filled with primer — not an easy task with spray paint because its application is so fine. I wish I’d bought some standard wood primer and done a coat by hand before moving over to spray cans for the rest. It would have saved some time at least.

The next coat was much heavier. It was actually several light coats, to prevent the paint running. You can do this within the hour of each with spray paint (at least, according to the paint can instructions), and my coats would have been at most 2–3 minutes apart. Just long enough for the paint to get tacky between each coat.

Unfortunately the ridge on the scallop was still present after the second coat, despite my sanding efforts. I think part of the problem was using a block for sanding that area out. D’oh.

Cue more sanding. This time without a block, but with a dust mask. I ended up using a hair dryer (on cold) to blow all the dust off/out of the guitar too, which worked really well.

A week later when we finally had some nice weather again I started with coat #3. This time I was absolutely confident I had got ALL the ridges COMPLETELY off the guitar. This coat was thick like #2, again made from many light coats. It took around an hour to fully spray out the guitar. I also discovered I wasn’t doing well with spraying the bottom edge, so laid the guitar flat on the ladder, sprayed that edge, then let the guitar drop into its hanging position for the remainder of the coat.

After the third coat there were still some minor ridges, but the paint has built up well over them. I managed to get this coat in on a Saturday, hoping it would be the last coat of primer before moving to colour coat.

Up until this point I had been dry sanding the guitar. Dry sanding is just normal sanding, but sawdust and paint tends to build up on the sandpaper so it quickly stops being effective. It can also damage the surface if you pull sandpaper loaded with dust across it. To avoid damage you have to replace the sandpaper as soon as it loads up.

Wet sanding is an alternative and although not all paint supports doing this, I had bought primer that was both wet and dry sandable. The concept here is you quickly dip the sandpaper into a container of water (with a little dish soap in it to help lubrication), then gently sand the guitar, and wipe off the water/paint. The surface shouldn’t be wet for any length of time. The sandpaper doesn’t build up with dust at all, and you end up with a nice smooth surface.

The bit no one tells you is that if you happen to cut through the paint into the wood, the wood will absorb the water and then new ridges appear. Yeah. So, that happened.

Despite this, wet sanding actually had me end up with a nicer surface where I had built up enough primer. It just meant that more sanding was required to remove the new ridges, and another coat of primer on the problem areas. So much for getting the colour coat on!

So at this point, the guitar needs to dry out, have the damage sanded off, repainted… then the colour coat can finally be applied.

My lessons so far:

  • Buy a kit if you are a newbie, no shame in learning on something that doesn’t matter so much.
  • Wear a dust mask for sanding and for painting, that stuff sucks.
  • Start with a low grit sandpaper — 600 or something rough — as a first sand on raw wood. Then you will actually take ridges off first time (not 3rd time!). You can move to a higher grit just before you paint.
  • Hand paint (not spray paint) the primer on.
  • Lie the guitar flat to get the bottom edge properly when painting.
  • Wet sanding is awesome but don’t do it unless you are sure you aren’t going to cut through to the wood.

Machine Learning, AI and Data Expert. By day I work training machines to think, by night I plot to take over the world. All views expressed here are my own.