Capping
From PyroGuide
Capping (or nosing) denominates one of the concluding steps in the manufacture of certain items intended for display purposes such as fountains or drivers. After applying prime the devices are "capped" by pasting about three turns of thin kraft paper around the upper end of the tube, overlapping the end by about 35mm.
The paper is pasted at the edge only and where it contacts the tube. The overlapping paper is employed to tie the match pipe in (in the case of display fireworks or set pieces) or to prevent the visco from being pulled out (in the case of consumer fireworks). The knot must not be too tight or else the match is tied off and fire transfer may fail.