The Broom Ledger
Bristle is either grown or extruded; this page compares the natural and synthetic families by stiffness, water behavior, and wear.
Broomcorn is the reference natural fiber: the seed-head tassels of a sorghum variety, long, straight, and springy. It sweeps dry dust better than almost anything and has anchored the craft since the late eighteenth century.
Palm and agave fibers cover the stiffer end. Bassine and palmyra, stripped from palm leaves, are coarse and tolerate water, which suits them to outdoor and wet work. Tampico, from agave, is softer and holds water well, making it a traditional choice for scrubbing.
Animal hair sits at the soft end. Horsehair and horsehair blends produce the gentlest common sweep, reserved for finished wood and other floors that scratch; they are poor on grit and worse when wet.
Synthetic bristles are extruded filaments. Polypropylene is the workhorse — stiff, cheap, and indifferent to water. Nylon is more resilient and keeps its set after bending. PET, often spun from recycled bottles, fills the middle. Polystyrene appears in lighter indoor heads.
Tip treatment matters as much as polymer choice. Flagged tips are split into fine forks that trap dust; unflagged tips stay whole and push heavier debris. The same filament, flagged or not, behaves like two different materials.
Wear and environment close the comparison. Natural fibers rot if stored damp and dry out if baked; synthetics survive both but deform near heat and build static on dry days. Matching fiber to surface is a materials decision before it is a shopping decision.
Further reading