While glissandi are completely doable on mallet percussion instruments, the capabilities are unfortunately less than its pianistic cousins. Pianos have an individual hammer to activate each note; even string instruments can be constantly and consistently activated with a bow, and wind instruments can be similarly manipulated with air. Mallet instruments, on the other hand, have only a mallet (or a few mallets) sliding back and forth without re-articulating. This causes glissandi to have very low dynamic ceilings amongst other obstacles. Below are a few things to consider to get the most out of the gesture.
Glissandi have to be quite quick to project at all. A slow gliss will merely sound like a very poorly played scale at a barely audible volume. This might be at odds with a gliss that is written to last a long time, which leads us to…
A gliss can be made to last longer without changing direction by having one mallet follow behind the other, having two mallets gliss simultaneously but in slightly different spots. The hands can cross over one another to prolong this effect indefinitely. While not exactly the sound that would be heard from a standard gliss, it is one possible solution.
A gliss over just a few notes is largely inefective, as it will probably sound like a pronounced beginning, and possibly ending) note, and nothing else. It’s probably best to just articulate each note individually if you’re going for a gliss-like effect over the course of, say, a perfect fifth or less.
Harder Mallets = Better Results
Well, “better” assuming you want a pianistic gliss. This is a general truth, however it’s especially so on instruments that react best to hard mallets. Xylophones and glockenspiels, for example, respond well to hard mallets and therefore can project in a very satisfying way. The spacing of crotales makes glissandi awkward. Chimes with the pedal down sound chaotic, which can be extremely cool.
See the video below for a few examples of different glissandi; they’re not all supposed to sound good!