Method
There are two primary methods for achieving glissandi on the tuba and euphonium—via the lips, in the form of a rip or harmonic glissando, or as a quasi-portamento involving the valves. In the first technique, the performer presses the desired number of valves down and uses the backpressure of the valves to force a glissando through the harmonic series of whatever valve combination is activated. In the second form, the valves are pressed during the glissando either in a sliding roll, or as a complete unit. The momentary half-valve effect allows for the buzz to slide between notes more easily, and if done with the proper amount of effort, makes a relatively smooth glissando. The second form of glissando is often used when a subtler or measured glissando is desired.
Necessary information
The lip glissando can be performed at a high volume and speed rather easily, but is much more difficult at lower dynamics. In contrast, the valve glissando is much more effective at lower speeds, but is somewhat clumsy at a higher rate.
If overdone, the lip glissando can be very fatiguing for the performer’s embouchure.
When performing the lip glissando, it can be difficult to pinpoint exact starting or ending points. It is exceedingly easy to “overshoot” an ending point, without dedicated practice.
The half-valve glissando can be difficult to perform at a high dynamic and for longer passages, but it is certainly achievable with practice.
Notation
Glissandi that are used ordinario may be notated in the typical fashion. It is advisable for the composer to clearly distinguish whether a lip glissando, valve glissando (quasi-portamento), or half-valve glissando is desired. The musical example below notates both a lip (overtone) glissando and a valve glissando, utilizing notations that are recommended for the techniques.
Relative Difficulty
Intermediate to Professional
Works to consider (bolded titles are particularly representative examples of this technique)
Encounters II – William Kraft
Concert Variations – Jan Bach
Three Essays – William Penn
Five Studies for Tuba Alone – David Reck
The Composer's Guide to the Tuba 