Bells up

Raising the bell into the air. Notated with a verbal instruction. Very striking when done by the whole horn section together, but primarily a theatrical effect.
Bells up:

glissando

Glissando

A slide in pitch between notes. Valve/lip glissando involves hitting as many harmonics as possible between two pitches. This is the standard glissando, but it is also possible to use the hand to slide a semitone.
Horn Glissandi
Glissando:
Hand glissando:

trills

Trills

Semitone trills work anywhere on the instrument. Whole tone trills can be more difficult, especially in the low to middle register. Lip trills between two harmonics work well in the upper and middle registers.
Trills:

tremolo

Tremolo or "Shake"

Tremolos are not really feasible on the horn.
Tremolos:



Cuivré

A brassy sound. Notated with a verbal instruction. (Germ. schmettern It. produrre suoni metallici). Use for limited periods only.
Cuivré: