USPS Automatable Mail Polywrap

Manufacturers and mailers of flat-size mail must comply with USPS-T-3204 which went into effect February 4, 2007. In 2006, the USPS conducted a thorough study of automatable polywrap films to ensure compatability of automation flats with flats sequencing systems ( FSS ) and stand alone mail prep ( SAMP ) according to standards AFSM 100 and UFSM 1000.

For specifics:

   Approved Polywrap and Polywrap Manufacturers



In brief, the key properties of stiffness ( a/k/a secant modulus ), coefficient of friction (does not “block” ), anti-stat were defined according to the following standards:

ASTM D374, ASTM D882, ASTM D1003, ASTM D1894, ASTM D 3354, ASTM D 4470



Simply put, the USPS wants a clear polywrap film which:

1. Has a coefficient of friction ( COF ) measured with ASTM D 1894 which is not too slick, not too tacky and does not exhibit “blocking”.

Coefficient of Friction measures whether a surface is slick or tacky. The values have an inverse relationship. In other words, a higher number is tacky and a low number is slick. COF is measured both film-to-film and film to mirror finish stainless because stainless has higher surface energy. Film tends to cling, or “block” more to metal than film.