Reading Grain Runout
© Frank Ford, 3/20/98; Photos by FF, 3/12/98
Any time you're working with wood, it's a good idea to know the direction of the grain. This is most important when working with spruce on the face of a stringed instrument. If you are removing a bridge, fingerboard or pickguard, you'll benefit from "reading" the grain runout.
The person who removed this bridge probably pried it loose from the front edge, jamming right into, and running with the grain on the left (treble) side:
This particular guitar top "tells" you from which side to approach lifting the bridge. When you look at the surface of the wood, and one side of a book matched top appears darker than the other, then you know you're looking "down" into the end grain of the wood:
Here we know to approach lifting the bridge from the neck end of the guitar on the bass side, and the bottom of the guitar on the treble.
And when you turn the guitar around, it figures that the dark side will be on the left as well, because the top sections are virtually identical, having been laid out like the pages of a book:
So the same thing is clear. Approach lifting the bridge from the bottom of the guitar on the treble side and the from the neck end on the bass side.
Let's look at that damaged top one more time:
See how the flaps are clearly lifted on the left (treble) side of the bridge scar? Obviously, this one was pried loose the wrong direction.
The patches on the bass side replace huge flaps that were pried up and broken off. Seems as though this guy pried both sides of the bridge from the wrong direction. Could be that it felt easier to push the knife under because the grain was splitting so easily, and he thought it was the glue line separating.
Take advantage of "grain runout" if you see it. Most guitars don't have this much runout, and many show none at all. But if it is present, it pays to be careful of grain runout!
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