Organ metal
Tin-lead alloy used to make metal organ flue pipes; a higher tin content gives a better sound.
What it means
Organ metal is the tin-lead alloy from which most metal flue pipes of the organ are made. Depending on the mixing ratio it differs in hardness, color and sound. A higher tin content gives a brighter, shinier metal that makes the pipe more stable and favors a brilliant, clear sound; a higher lead content makes the metal softer and the sound darker and rounder.
Musical use
The organ builder casts the metal into sheets, cuts plates from them, rolls them into tubes and solders them together. On cooling, certain alloys form a pattern called flowering. Besides tin-lead, zinc, copper and wood are used for certain pipes, for instance for large bass pipes. The choice of metal shapes the sound and durability of an organ over centuries.
Organ metal should be distinguished from other pipe materials such as wood, which sounds warmer and softer, and from pure tin, which is more expensive and sounds especially brilliant.
Performance practice
As an organist you do not influence the sound through the metal but you do through registration. Understand that stops with a high tin content often sound more brilliant than those with a lot of lead, and choose them accordingly for the tone color of the piece.