Soundboards will crack when exposed to excessive humidity and neglect. If a piano is played often the over-all tension on the strings remains even. By playing your piano and having it tuned twice each year you can avoid this expensive repair.
Soundboards can come unglued from the piano rim and from individual or multiple ribs, as seen in the photo. Two systems are used to compress the soundboard to the rib until the glue dries.
Once these two repairs are affected a pre-dried, spruce soundboard shim is inserted into each crack and glued in place using special clamps called go-bars. The top of the shims are chiseled flush with the soundboard.
After uniform sanding is achieved, all cracks in bridges soundboard repaired they are sealed in several coats of clear lacquer, sanding between coats.
In the video, Frederic “Ric” Sterry Smith and his technicians demonstrate the repair of a soundboard.
(1) Using go-bars to secure the soundboard to the ribs. (2) Bottom of Baldwin sound board – repaired (3) Preparing the soundboard cracks for shims
Want to see more? See soundboard repair on these fine instruments: