Kraft Paper – An Introduction
Kraft paper is a packaging material that gets its name from the Kraft pulping process, pioneered by Carl F. Dahl of Germany in 1879. Kraft in German stands for strong. The Kraft Pulping technique was a chemical process, consisting mainly of the cellulosic fibers of the wood. During the pulping process wood chips are cooked with a white liquor to break the bonds between the lignin, hemicellulose and cellulose, and extracting only the cellulose. The Paper made from this pulp is known as Kraft Paper!
Kraft Paper today is widely used in various types of packaging, including, Corrugated Cartons, Paper Sacks, Paper Bags, Food Boxes, Paper Cups amongst others. Whilst most of it produced is brown in color, bleaching it gives us Bleached or White Kraft, which also has endless applications. Without Kraft Paper we would have a very different world, as the packaging would not be secure and hygienic, and logistics and handling of our daily consumables would be a manace. Amazon wouldn’t be able to ship as much as it does, U-Haul wouldn’t be effective and the list of the conveniences we are used to today wouldn’t be possible.
Various Kraft Paper Types
Kraft Paper is usually manufactured from 45 GSM – 150 GSM for its use in various industries. Kraft Paper is stronger than the usual paper as it is mostly cellulose and has a high sulphur content, since the paper is generally brown, it does not require bleaching increasing the strength of the sheet. It is produced primarily from Softwood owing to the long fiber length, whilst some grades contain a blend of Hardwood, offering better stiffness and opacity. The different types of Kraft Paper include:
- Kraft Liner – Virgin Kraft generally used as a top layer in a corrugated carton, Food Service Boxes and off late owing to their environmental friendly nature, as paper cups
- Insulating Kraft – Used in the manufacturing of electrical transformers
- Absorbent Kraft – Used in the construction industry, widely used as a base layer for wooden flooring
- Coated Top Kraft Liners – Used for frozen food and beverage, primary and secondary packaging
- Test Liner – Manufactured from recycled virgin kraft, test-liners are the top surface of a corrugated carton, also used to manufacture paper bags
- Medium – Manufactured using recycled corrugated cartons, this grade is used as the fluting layer in a corrugated carton
- Black Kraft Paper – Black in color, this grade is used as a binding material in books, photo albums amongst other uses
- Sac Kraft – Used to make extensible, semi-extensible and non – extensible cement bags, amongst other sacs.
So why is Kraft Paper environmentally friendly? As mentioned majority of the Kraft paper used in the world is unbleached, leading to reduction in use of harmful chemicals such as Chlorine and Ozone, which are commonly used to bleach paper. Whilst Kraft Pulp is produced, the extracted Lignin and Hemicellulose, or otherwise known as Black Liquor, is an excellent source of energy and biofuel.
In fact, some paper trading companies have produced Black Liquor bricks that are used to construct houses! Kraft Paper is 100% Recyclable. Most of the lower value corrugated cartons are produced using Test Liner and Medium, which are produced using Old Corrugated Cartons (OCC) as a feedstock. Like most paper, Kraft Paper is 100% Biodegradable, with a lot of companies producing compostable kraft.
This is the primary reason it is gaining its importance as a primary packaging resource, rather than its traditional secondary or tertiary packaging use.
We hope we were able to shed light on Kraft Paper, and give you a brief introduction to its multiple uses, in our next post, we will be discussing the use of Kraft Paper in the Corrugated Board and Carton industry. You will be amazed to know the uses of Corrugated cartons and their derivates in the modern world.
Also, learn more about Machine Glazed paper.