$1 1928-B Silver Certificate Fr. 1602 Z–B Control Block Experimental Issue – VF

An  example of the Z–B block “control block” Experimental Silver Certificate (Fr. 1602) — a true standout for the small-size specialist. This BEP experiment, the first of its kind for small-size notes, ran during 1932–1934 and used X–B and Y–B blocks (from the 1928-A and 1928-B Series, printed concurrently) to test different rag content in the paper, while the regular-issue Z–B block served as the control.

The X–B block paper was produced with 50% linen / 50% cotton, while the Y–B block tested 75% linen / 25% cotton. This note is graded Very Fine (VF) with evidence of handling—fitting for a piece that was meant to circulate as the benchmark for the experiment, and a legitimately important issue for collectors who appreciate BEP production history.