Pick Your Plastic

The plastic bag is a common item that many are familiar with. Despite this, most do not realize that the plastic bag comes in a variety of different types and forms, with many different features and functions. This glossary will help you learn about the various types of bags and how they may best suit your packaging needs.


The most basic of plastic bag products is the flat poly bag. This bag made of polyethylene – a thin, flexible, plastic film – will protect your goods from dirt, dust, moisture, and other elements. Flat poly bags have no gussets, or folds. They have a length and width measurement, plus a measurement for thickness, referred to as the gauge.

Flat bags have the option of being bottom sealed, or side welded. Bottom sealed bags are cut individually from seamless tubing and are sealed at the bottom, making it the strongest seal available. This seal is useful for heavy duty type products. Side welded, or side sealed bags are made from folded poly sheeting, which are then sealed on each side. Because of the simple yet effective make of these bags, flat poly bags serve many uses in many industries.


This is your ziplock style bag. Ziploc is a trademark name that has become a common reference to this style of bag. These resealable bags are made with an interlocking track sealed into the top of the bag across the width of the open end. When a user pinches one end of the opening and slides their finger to the other end, this forces the poly zipper to lock and seal together. The use of reclosable, or ziplock bags is beneficial when there is need for multiple openings or repackaging of the product.

Reclosable bags can come manufactured in different ways. One way is a bottom-fill zipper bag, where a product is slipped into an already zipped bag from the bottom. The open ends are then heated and fused together, creating a safe and effective ziplocked bag. Bags can also be tamper-evident zipper bags. To ensure that only the customer can access the ziplock seal, such as when working with food products, customers can use a tamper-evident, tamper-resistant bag. This bag is essentially the same as a bottom-fill zipper bag, except for a pre-sealing above the zipper. Consumers can then tear away the perforated edge that reveals the zipper track. This ensures that the product inside has not been tampered with until the customer opens the seal.


Bags can also come with a resealable tape closure option. These are a self-seal bag containing tape on the lip of the opening, allowing for the bag to be opened and closed many times. Permanent tape closure bags incorporate an adhesive strip for a one-time seal. This type of bag is common for mailing products.


Gusseted bags come with folds or pleats in them. A gusset is the material that makes the side and bottom of this type of bag. By having the sides and bottom fold in, the bag can hold more product when it is expanded. Gusseted poly bags are useful and beneficial for packaging larger products, or when you need more room in a tote bag.

A bottom gusset is created by pushing the bottom end of a flat poly bag up, to make a pleat at the bottom of the bag. This type of bag is then side welded. Bottom gussets stand flat on a table or surface when unfolded. Similarly, a side gusset is formed by pushing the sides in, to again make an accordian-style pleat. Side gusset bags are bottom sealed and conform well to box-shaped products and goods.


These type of bags are generally prefered for applications where an easy method of dispensing is prefered. Bags on a roll are wound on a thick, durable cardboard core, measuring 3 inches in diameter. The bags are perforated at certain intervals which provides for easing tearing. The top opening can be made above or below the perforation. These bags are beneficial as they take up minimal storage space. Their common uses are for very long bags, garbage bags, produce bags, as well as dry-cleaning, and garment bags. Note that any flat or gusseted bag can be packaged on a roll if the customer prefers this storage method over individually cut bags placed in a box.

Another type of bag on a roll is the pre-opened bag on a roll, or auto bag. Auto bag, like Ziploc, has come to be a commonly used trade name for this type of bag. These bags are designed so as to be used on automatic packaging machinery. A pre-opened bag on a roll differs from regular bags on a roll in that the front layer perforation has already been broken. Instead of the perforation being closed and connected all the way through, a pre-opened bag is attached to the next bag only by the perforation on the back layer. The bags are rolled so that the front, open perforated layer is always on the outside of the surface, making it quick and convenient for automated packaging machines to fill the bag with product.


Wicketed bags are a side welded poly bag with two holes in the lip of the bag. The lip is a 1.5 inch area above the bag opening. A metal wicket is placed through the holes to hold the bag in place and to attach for easy dispensing. Rubber grommets are placed over the wickets to securely hold the bags in place. These types of bags are often used in high-speed automatic packaging systems and semi-automatic bag openers. Different types of machinery exists to aid with the fast opening and closing of wicket bags. The most common type of closures for this kind of bag are twist tie, heat-sealing, and tape closure. Wicketed bags are often seen in bakeries, enclosing bread and buns. They are also a common bag style used for packaging produce such as potatoes and apples, as well as ice. Besides these uses in the food industries, wicketed bags serve as packaging for different types of clothing like socks, undergarments, and other kinds of hosiery bags. Wicketed bags are useful and versatile. They can be made with a range of features like bottom gussets, resealable and permanent tape closures, hang holes, and perforations.


Also known as staple pack bags, header pack bags are efficient in loading operations. These are side welded bags with a perforated top lip attached and stapled to a header card. Typically packaged with 100 bags to a header card, these bags are used in semi-automatic packaging, and can also be used in manual operations. The header card contains hanging holes that allow you to keep your bags in order, and in an accessible spot for easy use. The serrated lip allows for product to be filled and torn away quickly. These bags are convenient for individual work stations.


A sealed header bag is sealed with heat at the top of the bag, along the width. Many products using this type of bag are loaded from the bottom and then sealed. A 1.5 inch area at the top of the bag is sealed off from the main bag compartment to keep the product clean and separated. A header seal bag prevents the contents of the bag from rising up to the top and interfering with the hang hole, or with the printing in the header area.

Find a bag that works for you? Multi-Pak USA offers all of these bags as stock items or as custom bags produced to the customer’s exact specification of size, thickness, and product information. Bags come in a variety of film colors, with your choice of plain, or printed with your company logo. Offering low minimum order quantities and a fast turn-around time, Multi-Pak USA has your order in the bag.

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