Packaging-Needs - Forside

Catch Kraft through the Eye of a Box

Kraft boxes are considered to be very tough in make and come in numerous shapes and sizes, damaging them or breaking them down is not an easy job. That is the reason consumers think they are very useful and their sole purpose is to protect any material or item inside of it. They consist of a material called wood pulp which is also called Kraft process I shall discuss this further later on in the article.


Raw material behind this pulp usually consists of wood, any type of it at that resulting into a softwood pulp, furthermore, there are chemicals induced into the fiber to strengthen the material, dye the color and to avoid moisture or bacteria growth within.

Types of Kraft’s

The qualities of Kraft paper are as follows: There are normal Kraft papers, which is strong and light. Then there is sack Kraft paper which allows durability, elasticity and does not tear. Absorbent Kraft paper made through special Kappa Hardwood has immaculate formation & is made with absorbency abilities. This type of box stays dry and strong throughout the packaging and delivery process. Spinning Kraft paper is very strong with surprisingly low weight; this is achieved through a one of a kind machine which focuses on strengthening and prolonging fiber. 

Twisting paper or as some refer to it as candy wrapping paper is very thin yet also have intense flexibility. They are usually used for Kraft Gift Boxes, Candy Wraps, Chocolate Wraps and More. They have a unique finish which requires a glossy finishing to the paper. 


Last but not the least Hunting cartridge paper, a special type of paper made to surround the shell and take it shape. It had to be very strong and needs to stretch to cover the shell entirely also holding everything intact. Furthermore, it is covered on the outside too to increase the strength.

The Process

As previously discussed the fiber which is extracted from the conversion of wood to the wood pulp is called the Kraft Process, it follows several steps through technology and chemicals to come out with the final product, wood pulp. Kraft process was made by a German who went by the name Carl F. Dahl in 1879, the technology of recovery boiler was a great help in advancing the Kraft process. 

Let’s start with the basic process firstly wood chips that range between 12 to 25 mm long and 2 to 10 mm thick are steamed. Mixed than with liquors consisting of white and black, the cooking penetrates into the structure of the chips. Wood chips that are heated into something called digesters, commonly producing 1000 ton of pulp a day. After several hours the solid pulp is collected and washed this process than moves on to the Recovery process. The following process requires the black liquor which contains about 15% solids is a target of effect evaporator. 


Increasing the solids in the black liquor to about 20% to 30% by this time the rosin soap rises and is skimmed off. Once that has been done the salts from the recovery boiler dissolve and a type of green liquor appears. It is not known what causes it to turn green but it’s mixed with calcium oxide which turns into calcium hydroxide to regenerate white liquor. 

Blowing, Screening, Washing & Bleaching

Once the chemicals have been induced and separated the final stages of the process take in place, the now cooked wood chips are blown into a blow tank which handles the pressure which in return releases volatiles which is condensed and collected as well. After the screening is used to separate any debris, anything not separated than becomes what is known as pulp. 


The washing stage comes right after and has at least 3 to 5 series of wash, the series might involve thickening, displacement or even diffusion. Washing is placed after oxygen removal and before bleaching process. Lastly, a variety of bleach stages come into play, this also depends on whether the manufacturers require brown paper or boxes, in that case, it’s not always needed to brighten the material. 

As it not only weakens the strength of the fibers but also adds to the cost of manufacture.

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