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EVF91040

Paperboard Envelope with Tongue Lock

Available in a wide range of custom configurations & material selection.
Order 1 sample. Or order 100K+ units. Or anything in between.
Affordable delivery across North America.
Design support, warehousing, testing, assembly available.
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Product details

Top highlights

Reusable tongue-and-slit friction closure
Ships flat and pre-glued for fast manual loading
Intended for thin items; overstuffing will release the lock

About this product

The EVF91040 is a flat paperboard envelope that uses a simple tongue-and-slit friction lock instead of adhesive or string. Delivered pre-glued and flat, it opens at the top for fast manual loading before the top flap folds over and tucks securely into the front face.

Because the closure relies entirely on board stiffness and friction, this envelope is designed for thin, flat items like gift cards, photos, and documents. It provides a clean, reusable presentation for retail or hand-to-hand delivery.

Common uses

Gift cards, photos, flat documents, internal kitting, retail presentation.

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Detailed dimensions

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Hand-loading flat retail and presentation items

Retail presentation and gift cards

The clean, tape-free closure makes this envelope a strong fit for gift cards, vouchers, and premium flat retail items. The recipient can easily open and reclose the flap without tearing the paperboard.

Internal kitting and document sorting

For internal operations, the fast manual tuck closure allows operators to secure documents or flat components quickly without applying labels or tape.

Photography and print delivery

A flat, protective sleeve for prints, certificates, or small artwork, keeping them clean during hand-to-hand exchange.

Hotel key cards and ticketing

Provides a clean presentation for hospitality passes and event tickets, allowing guests to reuse the envelope throughout their stay.

Retail, kitting, and hand-to-hand delivery

Hand-to-hand and in-store delivery

The friction lock is a strong fit for controlled handling environments where the envelope is handed directly to a customer or placed into a larger shopping bag.

Courier and postal shipping limits

This envelope is not natively secure for rough courier sorting. If mailed, the tongue lock can catch on sorting belts or pop open. It requires an outer shipper, a clear wafer seal, or a switch to an adhesive-seal mailer for postal networks.

High-volume fulfillment

Because the side seams are pre-glued during manufacturing, fulfillment teams receive a flat pocket that is ready for immediate insertion and a quick manual tuck, avoiding the slower process of tying strings or peeling adhesive liners.

When to consider dimensional mailers or sealed envelopes

Packing bulky or rigid items

If the product is thick enough to cause the front and back panels to bow outward, the locking slit will pull open and release the tongue. Bulky items require a dimensional mailer or a box with defined depth.

Tamper-evident requirements

The tongue lock can be opened and closed without leaving a trace. If security is required, look at mailers with tear strips or plan to apply a tamper-evident seal over the flap.

Board stiffness, surface friction, and packing labor

Board caliper and stiffness

The lock relies on the board's natural stiffness. If the board is too thin, the tongue may slip out easily. If the board is too thick, the side seams may resist folding flat. Standard folding boxboard usually provides the right balance.

Surface finish and friction

High-gloss coatings or laminations reduce surface friction. If the envelope is highly coated, the tongue may slide out of the slit more easily, requiring a slight adjustment to the tongue shape or a switch to an uncoated finish.

Manual packing labor

While the side seams are glued at high speeds on a straight-line folder-gluer, loading the product and tucking the tongue is typically a manual process.

Print layout and slit placement

The front face features a visible cut line to receive the tongue. Artwork should be arranged so critical text or logos do not cross this slit.

Tongue width, flap depth, and slit placement

Tongue and slit proportions

The width of the tongue and the length of the receiving slit can be adjusted. They must always match perfectly to ensure the lock engages without tearing the board.

Slit vertical placement

The vertical position of the slit on the front face is calculated based on the top flap's length and the board thickness, ensuring the flap folds over smoothly without binding.

Flap depth

The top flap can be extended to provide more coverage over the front face before the tongue engages, which changes where the slit sits on the presentation panel.

Packing details

Grain direction

Grain direction should run parallel to the main horizontal folds to prevent cracking on the primary hinge and to help the envelope lie flat.

Additional notes

Slit tearing under pressure

If the tongue is forced into a slit that is too small, or if the envelope is overstuffed, the ends of the slit can tear. The template automatically matches the slit length to the tongue width.

FAQs

Can I pack items that are slightly thick?

This envelope is designed for flat items. Overstuffing causes the front panel to bow, which widens the slit and causes the tongue lock to fail. For thicker items, a dimensional mailer or a carton with a defined depth is a safer choice.

Can this envelope be mailed on its own?

The friction lock is not secure enough for automated postal sorting belts, where the flap can catch and tear open. For courier shipping, the flap must be taped or sealed, or the envelope should be placed inside a master shipper.

Does a glossy finish affect the closure?

The tongue lock relies on friction to stay closed. Heavy gloss coatings or laminations make the board slippery, which can cause the tongue to slide out of the slit.

How is this envelope delivered?

It is produced on a straight-line folder-gluer and delivered flat. The side seams are pre-glued, so the packer only needs to insert the product and tuck the top flap.

Is the tongue lock tamper-evident?

The tongue can be tucked and untucked multiple times without damaging the board, making it reusable but not secure against tampering.

What board thickness makes sense?

Standard folding boxboard provides enough stiffness to hold the lock without making the side folds too rigid. Very thin board may lack the stiffness to keep the tongue engaged.

Can the tongue lock be automated?

While the side seams are glued on automated equipment during manufacturing, tucking the tongue into the slit is a manual packing step.

Will the slit interrupt my printed artwork?

The front face has a physical cut line to receive the tongue. Artwork should be arranged so critical text or logos do not cross this slit.