Cardboard boxes are a form of container used for the packaging, shipment, and storage of various products sold in retail to consumers or commercially to businesses. Cardboard boxes are a key component of the broader term packaging or packaging materials, which studies how best to protect goods during shipment during which they may be exposed to various form of stress such as mechanical vibration, shock, and thermal cycling, to name a few. Packaging engineers study environmental conditions and design packaging to mitigate the effects of anticipated conditions on the goods being stored or shipped.
From basic storage boxes to multi-colored card stock, cardboard is available in an array of sizes and forms. A term for heavier paper-based products, cardboard can range in manufacturing method as well as aesthetic, and as a result, can be found in vastly different applications. Because cardboard doesn’t refer to a specific cardboard material but rather a category of materials, it is helpful to consider it in terms of three separate groups: paperboard, corrugated fiberboard, and card stock.
This guide will present information on these main types of cardboard boxes and provide a few examples of each type. In addition, a review of cardboard manufacturing techniques is presented.
For more information on other types of boxes, consult our Thomas Buying Guide on Boxes. To learn more about other forms of packaging, see our Thomas Buying Guide on Types of Packaging.
Paperboard is typically 0.010 inches in thickness or less and is essentially a thicker form of standard paper. The manufacturing process begins with pulping, the separation of wood (hardwood and sapwood) into individual fibers, as accomplished by mechanical methods or chemical treatment.
Mechanical pulping typically involves grinding the wood down using silicon carbide or aluminum oxide to break down the wood and separate fibers. Chemical pulping introduces a chemical component to the wood at high heat, which breaks down the fibers that bind cellulose together. There are approximately thirteen different kinds of mechanical and chemical pulping used in the U.S.
To make paperboard, bleached or unbleached kraft processes and semichemical processes are the two types of pulping typically applied. Kraft processes achieve pulping by using a mixture of sodium hydroxide and sodium sulfate to separate the fibers that link cellulose. If the process is bleached, additional chemicals, such as surfactants and defoamers, are added to improve the efficiency and quality of the process. Other chemicals used during bleaching can literally bleach the dark pigment of the pulp, making it more desirable for certain applications.
Semichemical processes pre-treat wood with chemicals, such as sodium carbonate or sodium sulfate, then refine the wood using a mechanical process. The process is less intense than typical chemical processing because it doesn’t completely break down the fiber that binds cellulose and can take place at lower temperatures and under less extreme conditions.
Once pulping has reduced wood to wood fibers, the resulting dilute pulp is spread out along a moving belt. Water is removed from the mixture by natural evaporation and a vacuum, and the fibers are then pressed for consolidation and to remove any excess moisture. After pressing, the pulp is steam-heated using rollers, and additional resin or starch is added as needed. A series of rollers called a calendar stack is then used to smooth and finish the final paperboard.
Paperboard represents a paper-based material that is thicker than traditional flexible paper which is used for writing. The added thickness adds rigidity and allows the material to be used to create boxes and other forms of packaging that are lightweight and suitable to hold many product types. Some examples of paperboard boxes include the following:
Bakeries use cake boxes and cupcake boxes (collectively known as bakers’ boxes) to house-baked goods for delivery to customers.
Cereal and food boxes are a common type of paperboard box, also known as boxboard, that packages cereals, pasta, and many processed food items.
Pharmacies and drug stores sell items that are in drug and toiletry boxes, such as soap, lotions, shampoos, etc.
Gift boxes and shirt boxes are examples of folding paper boxes or collapsible boxes, which are easily shipped and stored in bulk when folded flat, and which are quickly refolded into useable forms when needed.
In many cases, the paperboard box is the primary packaging component (such as with bakers’ boxes.) In other situations, the paperboard box represents the exterior packaging, with additional packaging used for further protection (such as with cigarette boxes or drug and toiletry boxes).
Corrugated fiberboard is what one typically refers to when using the term “cardboard,” and is often used to make various types of corrugated boxes. Corrugated fiberboard properties are comprised of several layers of paperboard, typically two outer layers and an inner corrugated layer. However, the internal corrugated layer is typically made of a different kind of pulp, resulting in a thinner kind of paperboard that isn’t suitable to be used in most paperboard applications but is perfect for corrugating, as it can easily assume a rippled form.
The corrugated cardboard manufacturing process uses corrugators, machines that enable the material to be processed without warping and can run at high speeds. The corrugated layer, called the medium, assumes a rippled or fluted pattern as it is heated, wetted, and formed by wheels. An adhesive, typically starch-based, is then used to join the medium to one of two outer paperboard layers.
The two outer layers of paperboard, called linerboards, are humidified so that joining the layers is easier during formation. Once the final corrugated fiberboard has been created, they component undergoes drying and pressing by hot plates.
Corrugated boxes are a more durable form of cardboard box that is constructed of corrugated material. This material contains a fluted sheet sandwiched between two outer layers of paperboard and are used as shipping boxes and storage boxes by virtue of their increased durability when compared with paperboard-based boxes.
Corrugated boxes are characterized by their flute profile, which is a letter designation ranging from A to F. The flute profile is representative of the wall thickness of the box and is also a measure of the stacking ability and overall strength of the box.
Another characteristic of corrugated boxes includes the type of board, which may be a single face, single wall, double wall, or triple wall.
Single face board is a single layer of paperboard adhered on one side to corrugated fluting, often used as a product wrapper. Single wall board consists of corrugated fluting to which a single layer of paperboard has been adhered on each side. Double wall is two sections of corrugated fluting and three layers of paperboard. Similarly, triple wall is three sections of fluting and four layers of paperboard.
Anti-Static Corrugated Boxes help manage the impacts of static electricity. Static is a type of electrical charge that can accumulate when there is no outlet for electrical current. When static builds up, very slight triggers can result in a passage of electrical charge. Even though static charges may be rather small, they can still have an unwanted or damaging effect on certain products, specifically electronics. To avoid this, material handling equipment dedicated to electronics transportation and storage must be treated or manufactured with anti-static chemicals or substances.
Static electricity charges are produced when insulator materials come into contact with one another. Insulators are materials or devices that do not conduct electricity. A good example of this is balloon rubber. When an inflated balloon is rubbed on another insulating surface, like a carpet, static electricity builds up around the balloon surface, because friction introduces a charge and there is no outlet for the buildup. This is called the triboelectric effect.
Lightning is another, more dramatic example of static electricity buildup and release. The most common theory of lightning creation holds that clouds rubbing against one another and mixing together create strong electric charges amongst themselves. The water molecules and ice crystals in the clouds exchange positive and negative electric charges, which are driven by wind and gravity, resulting in increased electrical potential. Electrical potential is a term denoting electrical potential energy’s scale in a given space. Once the electrical potential builds to saturation, an electric field develops that is too great to remain static, and successive fields of air convert to electrical conductors very quickly. As a result, the electrical potential discharges into these conductor spaces in the form of a bolt of lightning.
Essentially, static electricity in material handling is undergoing a much smaller, much less dramatic process. As cardboard is transported, it develops friction upon contact with material handling equipment such as shelving or lifts, as well as other cardboard boxes around it. Eventually, the electrical potential reaches saturation, and friction introduces a conductor space, resulting in a spark. Electronics within a cardboard box can be damaged by these discharges.
There are various applications for anti-static materials and devices, and as a result, there are various types of these materials and devices. Two common methods of making an item static-resistant are an anti-static chemical coating or an anti-static sheet coating. Additionally, some untreated cardboard is simply layered with anti-static material in the interior, and the transported materials are surrounded by this conductive material, protecting them from any static buildup of the cardboard.
Anti-static chemicals often involve organic compounds with conductive elements or conductive polymer additives. Simple anti-static sprays and coatings are cost-effective and safe, so they are commonly used for cardboard treatment. Anti-static sprays and coatings involve conducting polymers mixed with a solvent of deionized water and alcohol. After application, the solvent evaporates, and the remaining residue is conductive. Because the surface is conductive, there is no static buildup when it encounters friction common in handling operations.
Other methods for protecting boxed materials from static build up involve physical inserts. Cardboard boxes can be lined on the inside with anti-static sheet or board material to protect the interiors from any static electricity problems. These linings can be produced of conductive foam or polymer materials and can either be sealed to the cardboard interior or manufactured as removable inserts.
Mailing boxes are available at post offices and other shipping locations and are used to hold items bound for shipment through the mail and other carrier services.
Moving boxes are designed to temporarily hold items for transportation via truck during a change in residence or relocation to a new home or facility.
Many pizza boxes are constructed of corrugated cardboard to provide protection during transport and delivery, and to enable stacking of completed orders awaiting pick-up.
Wax impregnated boxes are corrugated boxes that have been infused or coated with wax and are typically used for iced shipments or for applications when the items are expected to be stored in refrigeration for an extended period. The wax coating acts as a barrier to prevent damage to the cardboard from exposure to water such as from melting ice. Perishable items such as seafood, meat, and poultry are usually stored in these types of boxes.
The thinnest type of cardboard, card stock is still thicker than most traditional writing paper but still has the ability to bend. As a result of its flexibility, it is often used in post-cards, for catalog covers, and in some soft-cover books. Many kinds of business cards are also manufactured from card stock because it is strong enough to resist the basic wear and tear that would destroy traditional paper. Card stock thickness is typically discussed in terms of a pound weight, which is determined by the weight of 500, 20 inch by 26-inch sheets of a given type of card stock. The basic manufacturing process for cardstock is the same as for paperboard.
This article presented a brief summary of the common types of cardboard boxes, along with information about the manufacturing processes associated with cardboard stock. For information on additional topics, consult our other guides or visit the Thomas Supplier Discovery Platform to locate potential sources of supply or view details on specific products.
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Post time: Dec-10-2019