Hofner Colorama II restoration project (part 11) - flattening the warped plastic pickguard and tremolo cover

Among the many smaller jobs that have to be done to this vintage Hofner Colorama II is to flatten the warped plastic pickguard and rear tremolo cover. Here’s how they both looked before starting:

Pickguard:

Rear tremolo cover:

I decided to tackle the rear tremolo cover first, since it appeared to be a much simpler job and also easier to replace should things go horribly wrong. I really couldn’t find any information about this on the Internet, so I did what seemed logical in my head, which was to sandwich the plastic in-between two panes of tempered glass, clamp the whole lot together, and heat it with a very hot hairdryer.

Here’s the setup:

After 10 or 15 minutes of heating the area above AND BELOW the cover, I took the top pane of glass off to confirm that the plastic had become soft, then clamped everything back in place and left it to cool naturally. Since I wasn’t in a hurry, I left it for 24 hours, although I’m sure that wasn’t necessary at all.

The tremolo cover came out completely flat. You can see a corner lifting slightly in this photo, but it’s really nothing and will easily be held flat once it is screwed to the back of the guitar body.

Next up was the pickguard. Not only was there some warping raising it up off the guitar body, there was also some bulging around the edges of the pickups, due to the pickups themselves bulging (as discussed here: http://diystrat.blogspot.com/2011/12/hofner-colorama-ii-restoration-project_12.html). Even with the pickups removed, the plastic edges wouldn’t return to shape, so this would need to be dealt with too.

I tried the same trick as with the tremolo cover, but unfortunately the pickguard material is about twice as thick as the tremolo cover, and has a much larger surface area. Even after 20 minutes or so, I just couldn’t heat it up enough through the glass to make it soft. I didn’t want to apply the heat directly in case the surface of the plastic started to blister or something else equally damaging.

It was recommended that I try pouring boiling water over the plastic, so I tried this method next. Before clamping it in-between the panes of glass and leaving it to cool down, I quickly used a flat-edged tool to push the edges around the pickup holes more or less back into shape.

This method proved completely successful, but at a cost. The pickguard was now perfectly flat, but had discoloured horribly, as shown here:

An internet search brought up a suggestion in a car restoration forum to rub peanut oil into the surface to restore the black sheen, but this method proved useless.

Next option was to try black shoe polish, but surprisingly this didn’t make any difference at all either.

So, I decided to get a bit more aggressive and removed some of the surface with some steel wool. Success! At least I knew now that the discoloration was only on the surface and could be skimmed off.

The steel wool wasn’t really aggressive enough for most of the pickguard, so I sanded it with 400 grit sandpaper (having tried 2000 grit and 1200 grit first without success):

This method worked great, but of course we were now left with quite a rough surface, shown here:

The surface was then sanded with finer sandpaper in a more random direction to remove the lines from the 400 grit sandpaper, leaving us with a nice and flat, but somewhat dull, surface:

Finally, rubbing compound was used to shine up the surface.

You can see the difference already here:

And finally, here’s the end result.