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Home > About USPS & News > Forms & Publications > Postal Periodicals and Publications > Publications > Publication 2 - Packaging for Mailing > 4 Closing, Sealing, and Reinforcing > 4-5 Tapes
Tapes are used to close, seal, and reinforce mailing containers. Commonly
available tapes have pressure-sensitive adhesive or gummed adhesive, with
either reinforced (filament) or
nonreinforced backings.
However, certain
types of tapes (such
as cellophane and
masking tapes) are
not strong enough for
reinforcing.
The illustration at right shows how
sealing tape can be combined with banding or reinforcement tape to
produce an effective closure for boxes with flaps and for telescoping
boxes.
Pressure-sensitive tape is acceptable for closing and reinforcing mailing
containers. This type of tape is available with various cloth, paper, or plastic
backings, both plain and reinforced. Except for pressure-sensitive filament
tape, tape used to close and reinforce mailing containers may not be less
than 2 inches wide. Nonreinforced plastic tapes must be at least as strong in
the cross direction as in the machine (long) direction.
Pressure-sensitive tape works best when applied to clean surfaces at
temperatures above freezing. In below-freezing temperatures, the tape
should be rubbed down after it is applied.
Cellophane and masking tapes may not be used to close or reinforce
containers. These tapes may be used, however, on envelopes to augment
adhesive closures or on bags to cover staples.
Gummed tape is acceptable for closing and reinforcing mailing containers if
the adhesive is adequately activated, usually with water. If the adhesive is
improperly activated or the fibrous material of the container absorbs the
water, the gummed tape cannot stick to the container.
Gummed tape is applied correctly
if it remains attached to the
container during handling and
transportation and its removal
causes delamination or at least
a 50-percent fiber tear on the
surface to which the tape is applied.
The tape should be kept away from freezing
temperatures for at least 1 hour before its
application. Even properly applied gummed tape
tends to crack in extremely cold temperatures.
Gummed paper tape is available in two types:
• Reinforced Paper (Kraft). Reinforced paper (kraft) tape is acceptable
for closing and reinforcing irregular-shaped or soft-wrapped packages.
A mailing container closed with reinforced paper tape is more durable
than one closed with nonreinforced paper tape.
• Nonreinforced Paper (Kraft). Nonreinforced paper (kraft) tape is
acceptable for closing mailing containers if the tape is of at least
60-pound basis weight. This tape is inadequate for reinforcement.
When applied, the tape should extend at least 3 inches over the
adjoining side of the container.
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