4How to craft it
what it is for
Throw one down a dark shaft and it clings where it hits instead of tumbling to the bottom. That is the whole difference from the normal Glowstick, and it is a bigger deal than it sounds when you are dropping into a cave system and want to see the ledge you are aiming at. They burn out after a few minutes, so treat them as scouting light rather than a substitute for torches.
water and lava caves
Torches will not stay lit in water, which is exactly where you least want to be blind. Glowsticks work fine wet, and the sticky version stays put on the wall while the current would have washed a normal one away. The tooltip leaves off the line about working when wet that the other glowsticks carry, but it behaves the same.
marking a route
They are cheap enough to leave a trail behind you. One on each wall at a junction reads back on the map and gets you out of a long cave without retracing dead ends.