currency paper – US Notes

Fiber Inclusion Errors: When Foreign Threads and Materials Get Embedded in Currency Paper

June 15, 2026June 15, 2026 by

Fiber inclusion errors occur when stray threads, hairs, fabric fragments, or other foreign materials become trapped within the substrate of Federal Reserve Notes during the papermaking process. These visually striking and often underappreciated errors occupy a fascinating corner of error note collecting, with some specimens commanding serious premiums among specialists.

The Blue and Red Fiber Threads in US Currency Paper: Security Feature or Artistic Choice?

June 15, 2026 by

Those tiny colored threads embedded in your dollar bill are one of the oldest and most misunderstood security features in American currency history, dating back to 1942. This deep dive traces their origin, evolution, and surprising significance to collectors hunting varieties and high-grade examples.