Types of Closures

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Closures for clear plastic packaging include airplane or straight tuck, greenleaf, mailer lock and auto locking bottom.

Tuck Closure:

A tuck closure is a standard and very common style of closure. When closed, the main tuck panel locks itself between the 2 dust flaps of the carton. This is enough to hold most cartons closed, although Clearpak can add a locking tab to make it even more secure.

When choosing which closure best fits your product’s needs, we have to consider whether the product lends itself well to nesting. Nesting is the process of laying out a die or cutting pattern in the most efficient way in order to minimize the raw material waste. This keeps your costs for material as low as possible and allows us to reduce waste.

There are two main styles of Tuck Closure:

Airplane or Straight Tuck – Think of this layout like the wings of an airplane.  This style features closure panels on both the top and bottom that swing from rear to tuck in the front. The Airplane Straight Tuck differs from the standard Straight Tuck in that the top and bottom closure panels tuck from the rear to the front.

The Airplane tuck does not lend itself well to nesting.

Reverse Tuck- A reverse tuck carton features offset main tuck panels. One main tuck panel will fold from front to back and the other tuck panel will fold from back to front. The closure panels on top and bottom swing in opposite directions, with the bottom folding in the rear and the top folding in the front. This style of carton lends itself very well to nesting. Due to the offset main tuck panels and the way that the cartons nest together, a reverse tuck carton will produce the best and most efficient use of material when in production.


A greenleaf closure is a very secure closure style that can support a lot of weight. It is one of the strongest closure styles used in the plastic folding carton industry. It’s perfect for the wine and spirits industry cartons.

The greenleaf closure uses one main closure panel with two opposite facing tabs. These tabs then wedge themselves into a square aperture located on the other main closure panel locking the closure panels together and providing a strong and secure closure.

Mailer Lock:                                      

This mailer lock is a lock that folds from one of the main panels of a carton and locks into the opposite side. This style of lock can be made to work by itself or with a tuck style closure.

Auto Locking Bottom:                   

This is a pre-glued closure that allows the carton to fold down flat but then locks into place when the erect carton is folded. The pre-glued flaps automatically position themselves to close and lock. This style of closure is usually located at the bottom of the carton.

There is a lot of overlapping material with this style of closure. If you position your UPC code on an insert card and line the bottom panel with it, our transparent Clearpak cartons will allow your UPC reader or scanner to read the UPC with no problems or issues.

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