This post details how I went about repairing the lifting bridge on a Taylor 150e 12-String Dreadnought Acoustic Guitar featured in a
previous post. First of all, let me share with you that a lifting, or completely popped-off bridge is not an uncommon occurrence where acoustic guitars are concerned. And it doesn't only happen to the cheaper no-name ones; even those from big names are not spared.
The main cause of this malady is, as I see it; lacquer or varnish under the bridge. On lots of guitars I've repaired, the area under the bridge was not lacquer-free. In fact, there was no difference between this area and the rest of the top (soundboard). So, in effect, since the bridge was initially glued on, the glue on the bottom surface of the bridge had been adhering to a thin layer of lacquer/varnish; and not wood.
Given this scenario, it would only be a matter of time before string tension proved too strong for the thin layer of finish to handle, and the bridge would pull off the soundboard, taking with it a couple slivers of spruce; or whatever wood the soundboard was made from.
For a strong and long-lasting cohesion between the bridge and top, the bridge must be glued to bare wood. This can be achieved by taping off the area that would be under the bridge before applying lacquer or varnish (ie finish) to the top. Then, it would be a simple process of removing the tape, and gluing on the bridge. But perhaps this process consumes too much time, labor and dinero; hence the reluctance on the part of certain manufacturers to do it right.
On this particular Taylor 12-string, the majority of the bridge bottom-soundboard contact area was free of varnish. However, they'd retained a narrow band of varnish all around the inner perimeter of the bottom of the bridge. I guess that this was done for aesthetic reasons, ie to eliminate a visible "border" between the perimeter of the bridge and the varnish on the soundboard.
All fine and dandy, except for the fact that while the main area of the bridge bottom had been firmly glued to the bare spruce top, the perimeter had merely been glued to the varnish. That's a sure recipe for disaster! And so, string tension, compounded by a "bulging belly;" finally caused the bridge to lift from the soundboard.
After meticulously scoring the outline of the bridge (to minimize finish chipping), I carefully prised the bridge loose with a heated spatula. Much to my surprise, the bridge came off without much ado. Following this, I carefully scraped the old glue and varnish off the exposed wood, and leveled the area with sandpaper. I also scraped and sanded the bottom of the bridge clean of any glue or spruce remnants, made sure it was absolutely flat; and roughed it up a little with 180-grit sandpaper.
Now, since the Taylor was also suffering from a bulging belly aka acoustic belly bulge, I needed to address this problem before regluing the bridge. I'm happy to say that two few weeks of of humidifying, dehumidifying, and judicious clamping got the soundboard sufficiently flat again (I checked with a spirit level).
That having been taken care of, it was time to reglue the bridge with
Titebond III Ultimate Wood Glue. A dry test run was carried out with suitable cauls and clamps so I would know exactly what to do before any glue was applied. As it turned out, I needed four
StewMac Soundhole Clamps for the job.
I dispensed with the original tiny plastic bridge locating pins since they were terribly bent out of shape. Instead, I used two old bridge pins to ensure the bridge was properly aligned and positioned.The clamps stayed on until the glue squeeze-out turned brown, indicating that the Titebond III had dried and cured completely.
Once the clamps were off, it was time to clean up dried glue squeeze-out and any residue. There was also the extremely tedious task of cleaning dried glue from twelve bridge pin holes, as well as three holes for the
ES2 pickup sensors. The repaired areas were then waxed with Birchwood Casey Gun Stock Wax, and gently buffed.
I also treated the bridge to some
Dunlop Formula 65 Fretboard Ultimate Lemon Oil as it was looking kind of dry and thirsty. The fretboard was cleaned and rejuvenated with the same magic oil; and the frets polished to a high lustre. As per the owner's instructions, this Taylor 150e was strung to pitch with a set of
Elixir 11152 Nanoweb Lights. I also sanded the bottom of the saddle a tad to reduce the action at the bridge slightly.
