What Is Cardboard Made Of?

Cardboard is a common packaging material used in every industry as it prevents the stored items from being damaged. It is also considered to be very durable making it one of the best packaging materials for businesses. Knowing what your usual cardboard boxes are made of and their reusability can not only have a positive impact on your business, but also the environment.

Cardboard is essentially made from wood just like paper. It is usually made from the quick-growing pine tree pulp. However, recycled material can be used in the inner layer of a double or multiple walled cardboard as its quality is slightly lower than virgin pulp. It is worth noting though that cardboard recycling consumes lesser energy to be manufactured, hence increasing the chances of saving money and the environment.

Now that we know what is cardboard made of, let’s go ahead and understand the manufacturing process and its impact on the environment.

Initial Development

The process of converting wood into pulp is called ‘Kraft’ (meaning ‘strength’ in German) or sulfate process and it was first invented by German chemist Carl F. Dahl in 1884. He treated wood chips from Pine or Silver Birch trees with a hot mixture of sodium hydroxide and sodium sulfide and followed many mechanical and chemical steps thereafter to produce paper. This method is dominantly used in pulp mills today to manufacture paper.

Typically, cardboard boxes have a Kraft paper outer liner and a test paper inner liner because Kraft paper is better quality than test and its smooth finish can be easily printed on. On the other hand, test paper is made of recycled material or from hardwood tree pulp which is why it is cheaper and has a more abrasive quality.

Pulping

Pulping is the process of extracting fibrous materials and cellulose from wood to produce paper. This ensures that the resulting wood chips are clean and suitable for the purpose. For this, first, the trees are cut and lumbered to tons of logs. These logs then go through a machine to be debarked and chipped.

Out of the mechanical and chemical process (Kraft) of pulping the wood chips, the chemical one (Kraft) with the use of sulfide is more popular as it gives better separated and reduced lignin (a non-fibrous constituent of wood). This results in a better-quality paper. The mechanical process (test paper) on the other hand, is ideal if you want a low-cost solution with a higher output that is of lower quality. It involves grinding debarked logs against a revolving stone or disk grinder to break down the fibers. The stone gets sprayed with water to remove the fibers.

From Pulp to Cardboard

stacked-cardboard-boxes

The first stage is the ‘beating stage’ where the pulp is pounded and squeezed by machines. Based on the intended use of the paper, filler materials like clays and chalks or sizing such as gum and starch can be added followed by the removal of excess water content in a Fourdrinier machine. The nearly made cardboard is then pressed between wool felt rollers and then passed through steam-heated cylinders to eliminate any residual water content.

To get corrugated cardboard, the next process involves wounding the sheet onto a wheel. While for cardboard intended for other uses, the process is ended with coating, winding, and calendaring (smoothing of the surface).

Flutes

Flutes are what make the cardboard sturdy and protective. It is a wavy piece of cardboard sandwiched between two layers. The same process that was used to add ruffles to hats and shirts in the 18th century. It is used to create cardboard flutes now!

Single wall boxes have one layer of fluting whereas double wall boxes have two layers for extra strength. Depending on the thickness of the flute, we have A, B, C, E, and R grade flutes.

Corrugated Cardboard

Corrugated boxes are meant to be more durable than traditional cardboard boxes. They are made of three layers – outside layer, inside layer, and fluting with ruffled shape. This makes the overall packaging lightweight with a high strength-to-weight ratio.

While the traditional cardboard is better left for items like cards and cereal boxes, corrugated cardboard is ideal for shipping heavier and fragile products.

Is Cardboard Biodegradable?

Cardboard recycling is possible when the cardboard is not contaminated with oil, food, or water. Small businesses can reduce their waste using a cardboard baler to recycle cardboard, paper, bottles, and even aluminum/tin cans.

(Not sure what is a baler? Read our post on What is a Baler and Why Use Balers for industries, and get to know more about it!)

Cardboard is also biodegradable because it is made of natural materials ideal for composting. It can be broken down into its natural elements without leaving any harmful toxins. If the cardboard is unbleached, then even better. The nutrients from the compost can be used to boost the growth of plants in farms and gardens. Also, composting is a better option than recycling in the case of soiled-cardboard boxes such as those used in pizza boxes, egg cartons, paper towels, etc.

With cardboard used so enormously for packaging in every industry, it is important to learn its impact on the environment. Fortunately, paper and cardboard recycling benefits the environment by reducing deforestation and energy utilization. Moreover, corrugated cardboard can biodegrade completely within a year.

By reducing, reusing, and recycling; businesses can avoid unnecessary consumption of cardboard and also save tons of money, thus, taking a smart step towards sustainability. Read more on Cardboard Baler – Why do you need one?