Corrugate & Pallets

Complete Guide to Corrugate

4 mins

If we say the words ‘Corrugated Carton’ you immediately think of a brown box arriving from Amazon or your latest online order.

However, these two simple terms carry so much more depth, from the safety of your products during transit to the image portrayed of a business. In this blog we will cover off understanding of corrugated board descriptions including types of paper, fluting sizes etc.


So, the basic paper comes in various forms, suited to different needs which naturally all vary considerably, and directly contribute to the nature and colour of the corrugated case. The forms are as detailed below.

KRAFT – this is the most common form manufactured from softwood trees such as conifers. This paper contains virgin fibres, these fibres are referring to pure, un-recycled paper straight from the source. It is the strongest type of paper to use in the manufacturing of cardboard and is the easiest to print on. This is the most common form of cardboard used due to the fact that it has a higher burst level.

TEST – this paper is double layered which is also known as Duplex paper and is not a virgin material. Therefore this type is not as strong as kraft and not easily printable. The good news is it is a recycle made product and less costly, making it mostly used for the inside liner. Within this this test paper, there are two options T2 which is partly recycled paper liner and T3 which is a fully recycled liner.

These two paper options are the most popular types used for cardboard, however as per every product out there, there are many variations used to tailor to each individual need.

Paper Weights

When looking at the details of the carton, you also need to factor in the weight of the paper. This is measured in GSM, Grams per Square Meter. So if you were using a corrugated board that has a 150gsm Kraft paper liner, it will be shown as 150K, these weights mainly range from 115-300gsm. Again this list is not limited, and there is an extremely wide variety of gsms available.

Wall Types

There are three main types of walls when it comes to cartons, these consist of single, double and triple wall. The term single wall is derived from the fact that the carton is constructed using three layers of paper that are glued into one single, sturdy sheet. The interior of this cardboard sheet has one wavy line that is known as a flute (we will delve into that in a moment). Single Wall cartons are mostly used to packaging light weight products.

Double-wall corrugated boxes are constructed using two layers of corrugated cardboard (flutes), with a linerboard facing between them. This 5-ply construction provides added strength and stability. The double fluting adds greater protection, by providing a strong cushioning effect, absorbing any shock which so easily occurs during transit. This rigidity makes the cartons an ideal choice for items which require long term stacking storage etc.

Lastly, the tri-wall, the beast of all boxes! As the name suggests, this adds another layer of fluting and an additional liner. The triple flute layers and quality linerboard allows the packaging to resist bending and pressure from all directions. These cartons are best used for heavy or large items such as automotive parts, industrial equipment etc.


As mentioned earlier, the final aspect of the cardboard combination, is the fluting, this can make all the difference between a sturdy carton and a floppy mess! Flute is the name given to the wave shaped structure that provides strength to reinforce corrugated cardboard. This strength is to allow for stacking and to provide insulation to protect the package's contents. These flutes can vary from thin to thick, thin flutes such as the ‘E’ grade are more suited to lightweight cartons, where as the ‘A’ and ‘B’ end of the spectrum are of a wider nature, being used for transit packaging and the likes. The thing to remember is that they do work very well together, this can offer more rigidity than if you just used two ‘B’ flutes. When mixing flutes the grade changes to say ‘EB’ fluting which means you have an ‘E’ grade and a ‘B’ grade. There is also the C Flute which is the 4mm flute size in between A and B, this flute is commonly used for shipping cases, as it offers a good crushing resistance and has highly printable surfaces. 

In conclusion, we think it’s fair say you will never look at a corrugated carton again and think of it as just a brown box! If you do need more assistance when choosing the right cartons or have any questions, please do get in touch with the Swiftpak Team.