Manual of Traffic Signs

Retroreflective Sheetings Used for Sign Faces

Important Note: The current state of the retroreflective sheeting market is changing rapidly, due to development of new sheetings, requested changes to ASTM D4956, and changes in product offerings by manufacturers. This webpage will try to keep up with current events in reflective sheetings as they develop. However, the information on this page may be slightly outdated as events develop.

There are a number of different types of retroreflective sheetings in use on highway signs.
Some types, as classified by ASTM D4956-01, are:

Future Types:
Sign sheeting manufacturers have developed newer sheeting types with improved performance, and ASTM is considering creating newer classifications to codify the performance characteristics of these newer sheetings. Example of this include 3M Diamond Grade DG3 and Avery Dennison Omniview.

Important Note: The Types used in the ASTM sheeting specifications do not necessarily imply relative performance; i.e. a "higher"-type sheeting isn't necessarily better than a "lower"-type sheeting - it just meets different performance characteristics. Also note that some sheetings can meet the criteria of several ASTM Types.

Nearly all sheetings are available with pressure-sensitive backings for attachment to sign surfaces. Some sheetings are available with heat-activated backings, but with changes in sign manufacturing technology this type of adhesive is becoming less popular and less available.

Sign legends for retroreflective signs are produced by the following methods:

Colored inks used in sign silk-screening are translucent to allow reflectivity through the ink, whereas black ink used for signs is opaque.

Inks are available from 3M, Nippon Carbide, Avery Dennison, Nazdar, and other manufacturers.

Sheeting types normally fail in different ways, depending on how they are structured.

Single-layer types, such as Type I or II, usually fail by gradually losing their retroreflective intensity. This is due to increasing opacity of the pigmented material caused by ultraviolet ray exposure due to sunlight.

Multi-layer sheetings, such as Type III, often fail structurally - the outer colored layer delaminates and falls off, exposing the silver reflective underlayer to the elements, and ruining the contrast needed for legibility.

If properly applied and sealed to a good surface, most reflective sheetings are quite water, ice, and salt resistant.

Contact Information:

Special thanks to Seth Chalmers of Chalmers Engineering Company and H. Gene Hawkins Jr. of Texas Transportation Institute for their invaluable assistance in gathering this information.

More information may also be found from the Federal Highway Administration at

FHWA Retroreflective Sheeting Identification Guide

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Updated 15 September 2010 (coding)

Scripting: Richard C. Moeur
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Retroreflective Sheeting Identification Guide provided courtesy of Federal Highway Administration.
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