Flatwound Strings

A flatwound string starts as an ordinary wound construction (steel core, wrapped wire) but the wrap wire itself has a flat, ribbon-like cross-section instead of round wire, then the wound string is often ground or polished smooth. The result has no exposed grooves between windings, which is the whole point: fingers (and, on a fretted electric, frets) glide instead of catching on ridges.

What it suits

Jazz and some blues electric-guitar tone (the classic "thud" of a hollow-body archtop), fretless bass (a round-wound string’s ridges chew a fretless fingerboard in a way flatwounds do not), and players who dislike string-noise or finger squeak on wound strings.

How it ages

Flatwounds are famous for LASTING — the smooth surface traps far less finger oil and grime than a round-wound string’s grooves, so a good flatwound set can stay playable for years rather than weeks. The tradeoff is a darker, less bright tone from day one, not just as it ages.

Gear Warrior’s tension table (STRING_TYPES) has no flatwound entry — the flat-ribbon winding changes a string’s effective mass distribution enough that the round-wound unit-weight numbers above would not honestly describe it, so no tension figure is computed for a flatwound gauge on this site. Tension runs close to an equivalent round-wound gauge in practice, but "close" is not a number this table can stand behind.