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Smoother sailing for flat mailing

Sep 1, 2004 12:00 AM

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Dear Marcus: My clients and I need help preventing in-the-mail damage and slow service affecting larger printed mailpieces, such as catalogs and magazines. Where can I get plain-English guidance on these pieces beyond what's in the Domestic Mail Manual? Thanks!
Up to My Elbows in Crumpled Covers

Dear Crumpled Covers: You are describing pieces commonly referred to by the U.S. Postal Service (USPS) as flats — pieces that are too big to be mailed as letters but aren't packages either. By the time you read this, USPS should have released a new publication, “Recommendations for Designing Flat-Size Mail” (Publication 178). It's the product of more than a year of work by the Mailers Technical Advisory Committee (MTAC) and USPS HQ staff. MTAC includes representatives from many mailer organizations — the group meets quarterly to resolve technical issues.

Avoiding adverse design features

As reported in Postal World, the new publication “suggests ways flat-size mailpieces can maintain their design diversity and still be processed effectively on the Automated Flat Sorting Machine (AFSM) 100, the primary flat sorting machine used by USPS.” The publication highlights design features that can affect mail processing adversely and recommends solutions. Note that these are optional best practices, not new regulations.

According to MTAC and USPS, mailers should keep the following issues in mind when mailing flats:

  • Cover basis weight: When cover stock is not durable or heavy enough, there's an increased chance the cover will separate from the contents during processing — likely resulting in failed delivery of the contents.

    Recommended solution: Except for very thin flats, use a cover made of paper with a higher basis weight than the paper used for the body of a flat-size mailpiece. For heavier multi-ounce flats, particularly saddlestitched ones, look at the combination of the stock weight and coating when determining durability. For example, consider a cover stock of 50-80 lbs. for flats weighing more than six ounces.

  • Cover folds: Excessive compression can weaken the spine of the cover material and increase the chance for cover damage during processing.

    Recommended solution: Set your production machinery to use the least force needed to make a fold at the spine to avoid breaking the paper. Check the outside of cover folds for “whitening” at the fold crease.

  • Varnish: Slippery cover materials (such as those with varnish or high gloss) can twist during processing, making them more susceptible to damage. Also, thin flats with a lacquer cover can stick together under belt tension and cause misfeeds, resulting in missorts and delivery delays.

    Recommended solution: Check for low friction by twisting the cover slightly with the body of the mailpiece. If it slides easily against the body, you might consider changing the cover design or material. Minimize or eliminate the use of varnishes and aqueous or ultraviolet coating or other high-gloss coating on covers, particularly for thin flats. If you really want a heavily lacquered cover and the piece weighs more than six ounces, perfect-binding is a better choice than saddlestitching.

  • Gatefold covers: Gatefold-covered flats can “blow open” during processing, causing jams that can result in damage to the piece and delays.

    Recommended solution: Consider upgrading to a heavier cover for your gatefold — perhaps 75-lb. basis weight or more. Also, you might tab-seal the piece, opt to insert the flat in an envelope, go with a mailing wrapper or even polywrap.

Marcus J. Smith has been the editor and publisher of Postal World, an independent newsletter for business mailers, for more than 22 years. Contact him at

Meet Flat Stanley

The editorial staff of AMERICAN PRINTER is nominating “Flat Stanley” for honorary membership in the Mailers Technical Advisory Committee. As an expert on both being flat and being mailed, we think he'd be a natural to help draft “Recommendations for Designing Flat-Size Mail” and other USPS publications.

Stanley, the titular character of Jeff Brown's children's book, was squashed flat by a falling bulletin board. Flat Stanley, as many school kids know, visits his friends by traveling in an envelope.

A group of teachers created “The Flat Stanley Project” to encourage students to practice their writing skills. See