Paper Bags & Paper Shipping Sacks
Paper bags and shipping sacks come in a variety of shapes and sizes. Many paper bags, including lunch, shopping and grocery bags, are often made from a single layer of paper while other types are made from multiple layers. Shipping sacks, also referred to as multiwall sacks, are flexible containers made from more than one wall of paper and other protective barriers.
Commercial paper bags were first manufactured in England in 1844. In 1852, Francis Wolle invented a bag making machine in the United States, then further advancements were made to include glued sacks and the gusset design. The sturdier, multiwalled sack replaced cloth sacks in the 1920s and were then used to hold cement.
What Are Paper Bags and Paper Shipping Sacks?
A paper bag is a pre-formed container made from paper. Typically, they are produced from Kraft paper due to its elasticity and tear-resistance properties. Paper bags usually have an opening on one side for easy packaging.
Depending on its intended use, paper bags vary in size, strength and characteristics. They come in sizes as small as traditional brown lunch bags and as large as residential yard and food waste bags. If the bag’s intended contents are generally lighter, paper bags are typically made from a single layer – called a ply - of paper. However, if the intended contents are generally heavier, they are made from multiple layers of paper and can include other flexible materials to increase strength. Finally, paper bags exist with or without handles for carrying and with or without printing and/or brand logos on the exterior.
Paper Shipping Sacks
Paper shipping sacks, also known as multiwall paper sacks, are shipping containers made of high quality and heavier weight Kraft paper. They are generally used for transporting bulk materials such as sugar, flour, fertilizer, animal feed, dry chemicals and cement.
Shipping sacks can have as few as one ply of paper but most are made from several plys and other protective barriers. Similar to paper bags, Kraft paper is used for its unique properties. An additional external layer is produced in order for the content’s name and other information to be printed on the outside. Depending on the sack’s end-use, bags can be coated with a plastic or paper film, foils, laminations and other treatments to create wet-resistance, insect or rodent barriers and other product protection safeguards.
What Kinds of Products Are Made From Paper Bags and Paper Shipping Sacks?
Paper bags are used for:
- Shopping bags
- Grocery bags
- Produce bags
- Paper bread bags
- Yard waste
- Food waste
Paper bags are also an ideal container to hold compostable waste as unlined, Kraft paper bags are compostable themselves.
Paper shipping sacks, also known as multi-wall paper sacks, are often used as containers to ship bulk materials, including:
- Animal feed
- Dry food ingredients
- Dry chemicals
Why Use Paper Bags and Paper Shipping Sacks?
Paper bags and shipping sacks have numerous advantages, including:
Paper bags and sacks are a cost-efficient option for shippers that offer an advanced degree of customization. Because of their flexibility, they can be custom-designed to meet exact requirements and provide the highest degree of product quality protection at the lowest cost that meets normal handling, shipping and service requirements. Due to paper bags and sacks’ ability to be folded and flattened during transport, they can be shipped in small, tight spaces.
For shipping sacks, the flexibility of the package makes them a convenient option as no more material than necessary is used to package products of all shapes, sizes and volumes. Paper bags are sturdy, easy to carry and hold a lot of items without breaking.
Paper bags and shipping sacks are made from a renewable resource, trees that are replanted to ensure a sustainable supply. The U.S. grows more wood than it harvests and there are 20 percent more trees in the U.S. now than there was on the first Earth Day in 1970.
Paper bags and shipping sacks are recyclable, reusable and compostable. Paper bags especially are highly recycled and are a fixture in community recycling programs throughout the country.
Due to their ability to conform so closely to the volume of material being packaged, no overpackaging is needed.
How Are Paper Bags and Paper Shipping Sacks Made?
The first step in the process is to make pulp. Pulp can be made from either virgin fiber, which are wood chips, or from recycled paper products.
Wood chips (virgin fiber) are cooked using a chemical process in essentially a pressure cooker known as a digester. The wood fiber is separated into cellulose fibers, lignin (the wood glue that holds the tree together) and other substances such as sugars. Cellulose is an essential building block in the cell walls of trees and plants, helping to make them strong. The pulp is then washed to clean it and separate it further from the other tree components. After the pulp is washed, it is screened for further cleaning.
For mills using recycled materials, pulp is made by mixing the recovered fiber with water in what resembles a large blender called a repulper. In the repulper, the pulp is separated to create individual fibers in a slurry. From there, the pulp is washed and screened to further separate the fiber from other debris like dirt.
The pulp, which maintains its natural brown color, then needs to be formed into a sheet on the paper machine. At the wet end of the paper machine, the pulp flows onto a moving endless belt with a screen to filter out water and form a web. Further down the line, in the press section, the pulp, which looks like a brown sheet, goes through several presses to further remove excess water. At this point the web of material still must shed water, so it passes into a dryer. Unlike making other paper products, when making bag stock, to reduce the sheet’s shrinkage, creating stronger and more durable paper that can withstand stretch, it’s air dried using a FLAKT dryer instead of a cylinder dryer. After drying, the bag paper goes through rollers and is reeled.
Depending on what kind of container is being produced, different processes take place to produce the final products. For example, to make standard paper grocery bags, the sheets of paper are folder and glued together by machines and separated into batches.