Every dating search starts the same way: find the maker’s name, then find the serial number. The name is usually engraved on the bell in plain sight. The number takes a little more looking — but brass makers follow a few strong conventions.
The valve casing rule
On valved instruments — trumpets, cornets, flugelhorns, euphoniums, tubas — the serial is stamped on the valve section. The most common spot is the second valve casing, often on its rear wall. Bach stamps it there (the exact side and position changed by era: early New York horns horizontal on the reverse side, post-1990 Elkhart instruments vertically at the bottom casing). Conn marks the back of the second valve casing vertically. For King, Olds, Holton, Blessing, Buescher and Getzen, the second valve casing is the first place to look.
Trombones: bell first, slide second
Slide trombones have no valve section, so makers stamp the bell — commonly near the rim or on the slide receiver. One warning from the archive’s Bach coverage: on many Bach trombones the bell and the slide carry different numbers, because the parts were produced and numbered separately before assembly. Date the instrument from the bell.
Horns: the rotors
On French horns the serial usually sits on a rotor casing or the valve section — Conn marks several spots (trigger rotor, finger-lever bracket, first and third rotors) depending on the era. Jupiter’s official chart puts horn serials near the mouthpiece receiver: third valve casing on single horns, fourth on doubles.
Read the whole marking
Copy every character: letters and leading zeros are part of the number. At Getzen the series prefix (A, BP, EC, K, SK…) selects which table the number belongs to. At King, two-digit prefixes of the 1986–1995 era are read as “prefix + 50 = year”. A letter-prefixed number on a Bach, meanwhile, usually means a student or non-domestic line — worth knowing before a search returns nothing.
When you have both the name and the complete number, start from the brand directory — each maker’s page has its own serial lookup with the locations documented above where the archive knows them.