density, hardness, export · what is measured kept apart from what is taste
Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.
Three sizes in one archive — from a sheet on the fridge to a poster on the wall.
Density and hardness are averages for dry wood from The Wood Database, checked 2026-07-30; within a species they vary noticeably. CITES status checked on the same date.
Wood shrinks about 1.7 times more across the growth rings than along the radius: for Sitka spruce, 7.5 per cent against 4.3.
So a soundboard is cut on the quarter — not for the even grain pattern but so that a dry winter pulls it in by half as much. That is arithmetic, not aesthetics.
One practical rule follows: keep an acoustic between 45 and 55 per cent relative humidity. A crack in the top is almost never bad glue; it is a board that has shrunk across the fibres.
Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 7 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.
two shapes, twelve chords each
12 keys · key signatures · relative minors
one coil or two · six builds · where it sits along the string, and how high above it
15 chords every beginner starts with · standard tuning E A D G B e