Materials from the Postmaster General's Collection

Sikorsky Helicopter

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36¢ 1988 Sikorsky airmail stamp

This 1988 airmail stamp honoring aviation pioneer Igor Sikorsky is one of a handful of U.S. stamps produced with gravure and engraving—a technically difficult combination. Most of the stamp was printed in gravure, but the crisp VS-300 helicopter was produced with engraving.

Like many modern U.S. stamps, this one includes a “taggant” visible only in ultraviolet light. Taggants allow sorting equipment to locate stamps on envelopes. They can be embedded in the paper or added as a coating; here, a tagging ink was mixed into the special light blue ink.

Artwork, Model, and Die Proof for 36¢ 1988 Sikorsky Airmail Stamp

Original artwork, 36¢ 1988 Sikorsky airmail stamp

Approved working model, 36¢ 1988 Sikorsky airmail stamp, signed by Fletcher Acord, Associate Postmaster General, December 1987 (shows value as 44 cents)

Die proof, 36¢ 1988 Sikorsky airmail stamp

Proof Sheets for 36¢ 1988 Sikorsky Airmail Stamp

These proof sheets include “progressive proofs” for the gravure portion of the stamp—which progress from one color of ink to all five inks, adding one ink at each stage—and separate one-color proofs for each color. In addition, they include a proof sheet that’s only for the engraving portion of the stamp, and a final proof sheet that combines both gravure and engraving.

36¢ 1988 Sikorsky Airmail Stamp Progressive Gravure Proof Sheets

Light blue

Light blue and magenta

Light blue, magenta, and cyan

Image box with only text, Image not available

Light blue, magenta, cyan, and yellow

Light blue, magenta, cyan, yellow, and black

One-Color Gravure Proofs for 36¢ 1988 Sikorsky Airmail Stamp

Light blue





Proofs for Gravure and Engraving for 36¢ 1988 Sikorsky Airmail Stamp

Engraving proof sheet

Gravure and engraving proof sheet