Day 176: Curling for Fun and Profit

Once I settled on the locations of the bridges on the soundboard, I could go ahead and make some more drastic measures to get things into place. For instance, the best way to position the bridges into the soundboard is to drill holes into them and nail them to, say, a piece of plywood under the soundboard.

As you may recall from my last post, I positioned the bridges according to their original locations on the R.K. Lee drawing of the 1640 as it currently sits in the Yale Collection of Musical Instruments. It was fairly nerve-wracking driving nails into my beautiful, pristine soundboard, but it was required, so there you go. And I did likewise with the 4' hitchpin rail, which will be mounted on the reverse.

More than anything, these become positional guides during glue-up, which will happen this weekend.

Another interesting aspect of soundboard preparation is the application of "sizing". Size is simply diluted glue. In this case, it's diluted glue made from animal protein in an 11:1 water to glue ratio. Sizing is typically used for later gluing because it will soak up and guide full-strength glue during a gluing session. In this case, it's intended to tighten up the soundboard, enhancing it's tonal qualities.

Now, the really interesting aspect of this exercise is the curling it produces on the incredibly thin (2-3mm) jointed piece. The top did not produce much curling (this is probably a photo from after it had settled down a bit).

The back was another matter entirely.

As I like to say, "Oh, boy." As nerve-wracking as driving nails into the precious thing was, watching it curl like this put my teeth on edge, so I stepped out of the shop for a couple of hours. When I returned, this is what I saw:

Whew. The little fella had settled down considerably and I could breath much, much easier. Of course, this is what Owen Daly said would happen. I trust him completely, but it was still interesting to observe.

Another aspect of the sounboard is the apparent discoloration. The photo of the top was taken while it was still pretty wet with the size. When it's dry, it maintains a consistent cream color. This was intentional. When I purchased the wood, it was in a stack of "piano wood" that had been sitting in a retail space for the better part of 15 years. This resulted in the outside of the wood darkening a bit. I purposely put the darker sides on the reverse. Once the soundboard receives the bridges and a little paint, all will be well.

Until next time...