Kraft paper is paper made from kraft pulp, produced by chemically separating wood fibers while preserving much of their strength. It is widely used for bags, wrapping and packaging. The name comes from the German word Kraft, meaning strength. Its familiar brown form uses unbleached pulp, but kraft pulp can also be bleached to produce white paper.

For a brand choosing packaging, the useful distinction is between the paper and the package built around it. A kraft shopping bag relies on its paper, folds and glued joints to carry a product. A rigid gift box wrapped in brown paper gets most of its stiffness from the board beneath. Understanding how kraft is made helps explain its color, strength and surface; understanding the construction shows where those properties matter.

How kraft paper is made

Manufacturing has two main parts: making pulp by separating the fibers, then forming those fibers into paper. The sequence below follows virgin kraft made from fresh wood. Recycled grades begin with recovered paper, which takes a different preparation route before sheet formation.

1. Prepare the wood

Raw material can include pulpwood and suitable chips from sawmills. Logs are debarked and chipped, and the chips are screened for reasonably consistent size so they cook evenly. Wood species also influence the result. Softwoods such as pine and spruce generally supply longer fibers that contribute to strength. Shorter hardwood fibers can help produce a more uniform sheet and a smoother printing surface. Mills choose fiber mixtures to suit the intended grade.

2. Cook the chips to release the fibers

Wood contains cellulose fibers held together within a structure that includes lignin, a natural binding material. In a pressurized vessel called a digester, the chips are cooked with heat and an alkaline solution containing sodium hydroxide and sodium sulfide. This solution is called white liquor. It dissolves much of the lignin and some other wood constituents, allowing the fibers to separate.

Controlled chemical pulping preserves fiber length and integrity better than mechanically grinding wood apart. Those fibers later form a bonded network in the paper sheet, contributing to tensile strength—the ability to resist pulling—and resistance to tearing. The final strength also depends on the fiber mixture, sheet formation, paper weight and moisture conditions.

3. Wash and screen the pulp

After cooking, the pulp is discharged and washed to separate the fibers from the spent cooking liquid. This dark liquid, called black liquor, contains dissolved wood substances and pulping chemicals. Screens remove incompletely cooked pieces, knots and other unwanted material. Washing and screening prepare a cleaner, more consistent pulp for the next stages.

Where the cooking chemicals go

Black liquor enters a recovery system. Evaporators concentrate it, then a recovery boiler burns its dissolved organic material to generate heat for steam. The inorganic chemicals are recovered and treated to regenerate cooking liquor. Lime is used in this treatment, and a kiln regenerates the lime for reuse.

This loop is central to kraft production: it reduces the need for fresh cooking chemicals and uses material removed from the wood as fuel. The mill still has chemical losses, emissions, wastewater and energy demand to manage; recovery makes those flows more efficient rather than eliminating them.

4. Keep the pulp brown or bleach it

Unbleached pulp retains residual lignin and other color-producing components, giving it its brown shade. For white grades, further treatment removes or alters these colored substances to increase brightness. Bleaching changes the appearance while retaining the pulp’s kraft origin. This choice establishes the background for the packaging design: brown paper contributes its own warm tone, while a white base makes pale colors and full-color images easier to reproduce.

5. Prepare the fibers and form a sheet

The pulp is blended and refined. Refining mechanically works the fibers to improve their flexibility and the contact available for bonding. Its intensity is adjusted to the grade because it also changes properties such as density and drainage. Additives may be introduced to develop particular characteristics; for example, sizing helps control how readily liquids enter the paper.

A dilute mixture of pulp and water is then distributed across a moving mesh on the paper machine. Water drains through the mesh, leaving a continuous wet mat of fibers. Even distribution matters: variations at this stage can become differences in thickness, appearance and strength across the finished sheet.

6. Press, dry and finish the paper

The wet sheet passes through presses that remove more water and bring the fibers closer together. Heated drying cylinders then evaporate much of the remaining moisture. As the sheet dries, bonds develop between contacting fibers, giving the paper its usable strength. This is how a watery pulp suspension becomes a material that can be wound, printed, folded and glued.

Finishing determines more of the surface character. Calendering smooths the paper between rolls; machine glazing can produce a smoother, shinier face on one side. Other grades retain a more open texture. Coatings may be added for printing or functional requirements. The paper is wound into reels or cut into sheets, with grade checks covering properties such as weight, thickness, moisture and strength. Packaging conversion then turns it into printed, cut, folded and assembled products.

What different kraft paper descriptions mean

Kraft descriptions often answer different questions about the same sheet. A paper can be virgin-fiber, unbleached and surface-treated at the same time. Separating fiber source, color and finish makes samples and quotations easier to compare.

Recycled kraft takes a different starting route from fresh wood. Recovered paper is mixed with water and agitated to separate its fibers, then cleaned and screened. Deinking may be used where the intended grade calls for it. The resulting stock proceeds through paper preparation, forming and drying. It does not need to repeat the original wood-chip digestion simply because the finished paper is sold as kraft.

Repeated processing and drying can reduce fiber length and bonding potential. Mills manage this through recovered-paper selection, blending and sheet design. Consequently, recycled content is useful information about the material’s origin, while the grade’s actual properties establish whether it suits a bag, sleeve or box.

In commercial use, kraft can describe virgin kraft paper, recovered-fiber grades or the appearance of a finished package. A brown surface alone establishes neither the fiber recipe nor a strength level. A useful material description identifies the actual stock, its fiber composition, weight and surface treatment.

Paper, paperboard and a kraft box perform different jobs

Paperboard is generally thicker and stiffer than wrapping or bag paper and may contain several layers. For packaging selection, its thickness and construction matter alongside its weight. GSM means grams per square meter: it measures mass per area, not thickness. Thickness is often called caliper. Two materials with the same GSM can differ in density, thickness and bending stiffness, so a higher number alone does not define a better package.

A shopping bag: the paper carries the load

In a shopping bag carrying a boxed fragrance set, the paper walls bear pulling forces while stress concentrates around the handles, folds and bottom joints. Increasing paper weight may strengthen the walls, but a poorly attached handle can still fail first. Bag development therefore brings the paper grade together with handle reinforcement, seam design and adhesive performance. A loaded sample shows how those choices work as an assembly, including where the paper stretches or a joint begins to lift.

A rigid gift box: the cover and core have separate roles

A jewelry gift box may use relatively thin brown cover paper wrapped around thick grayboard. The cover supplies the visible color, texture and printed detail. The board supplies most of the rigidity, while the insert holds the jewelry in position. Choosing a heavier cover can affect how neatly it folds around corners more than it changes the box’s structural strength. A good sample therefore needs both an attractive surface and convincing construction: clean corners, secure wrapping, a well-fitting lid and appropriate product support.

A corrugated mailer uses another construction: flat liners bonded to a fluted layer. Its brown outer liner may contain virgin, recycled or blended fibers, while the fluted structure contributes stiffness and cushioning. The complete board, box design and packing arrangement determine its shipping performance. Calling it a kraft mailer describes only part of that system.

Printing on kraft: the paper color joins the design

Many printing inks are partly transparent, so the substrate contributes to the color you see. On brown kraft, a pale pink may become muted and a light blue may look darker or less clean than it does on white paper. Areas left unprinted will show the paper’s brown tone. This can produce a coherent, warm design when the artwork is developed around the material.

If bright graphics or close brand-color matching are central to the design, a bleached or white-faced material provides a more straightforward starting point. Printing an opaque white layer beneath selected colors can be another route where the printing process supports it, although coverage and opacity need evaluation. At CMIC, we can develop print samples on shortlisted stocks so you can compare the actual color result, paper shade and surface together.

Texture and absorbency also influence the result. An open, absorbent surface can soften fine detail or reduce the density of printed areas; a smoother grade may reproduce small elements more cleanly. On a jewelry box, a crisp dark mark or restrained foil detail can give the brown surface a focal point while leaving much of the paper exposed to the hand. Foil coverage, fine lettering and embossed detail deserve a physical sample because their appearance depends on the particular paper and finishing setup.

Moisture and coatings change how kraft behaves

Cellulose absorbs moisture, and ordinary untreated kraft paper loses stiffness and strength as it becomes wet. A bag that carries a glass candle comfortably when dry can behave differently if its base becomes soaked. Humidity can also change paper dimensions and stiffness. The relevant question is the exposure the package must withstand: indoor handling, occasional splashes, prolonged dampness or protection of a moisture-sensitive product over time.

Different treatments address different needs. Sizing controls liquid absorption. Wet-strength treatments help the fiber network hold together when damp. Barrier coatings or films restrict the passage of particular substances, while a mineral coating intended to improve printing may offer little useful water protection. Grease resistance, splash resistance and resistance to water vapor are separate properties: a surface that sheds a brief splash may still allow moisture vapor through during storage.

A protective layer also changes other choices. It can alter the feel of the paper, its folding behavior, adhesive bonding and how it separates during recycling. Water may still enter through exposed edges or seams. The useful approach is to match the treatment to the product’s actual exposure, then assess the assembled package as well as the sheet.

For direct food contact, the complete construction—including paper, coatings, inks and adhesives—needs an appropriate basis for the intended food, contact time, temperature and destination market. Brown color, bleaching or virgin-fiber content alone does not establish that suitability.

Is kraft paper environmentally friendly?

Kraft can be a useful choice for paper-based packaging, but its environmental performance follows the whole material journey: fiber sourcing, mill operations, the amount and construction of packaging used, and what happens after use. Its brown appearance is a design characteristic; the environmental case comes from those underlying decisions.

Recovered fibers keep existing material in use and reduce reliance on fresh pulp. Virgin fibers provide new material to a system in which fibers are gradually lost or become less suitable for further use. For either route, traceable sourcing and documented recycled-content information make the material choice more meaningful than an unqualified environmental label.

At the mill, chemical recovery puts dissolved wood material to work as fuel and returns cooking chemicals to the process. Unbleached grades omit the bleaching stage, but a comparison between papers still depends on energy supply, water use, treatment systems and the quantity required. A lighter package that protects the product adequately may offer a more useful improvement than changing its surface color.

Clean, dry, unlaminated kraft paper is commonly compatible with paper recycling, subject to local collection rules and receiving-mill requirements. Recycling works by separating fibers in water, so coatings, adhesives, wet-strength treatments and attached materials can affect recovery. A kraft-covered gift box with a foam insert and ribbon has several components to consider. Where function allows, simpler constructions and readily separable parts make the disposal route easier to communicate.

Recycled content and recyclability describe different stages of the material’s life. A virgin-fiber paper can be recyclable, while a recycled paper may become harder to recover after lamination. Cellulose can also biodegrade under suitable conditions, but a compostability claim must address the complete finished material and the intended composting conditions. Coatings and attachments remain part of that assessment.

Turning a kraft reference into packaging for your product

At CMIC Packaging, we can help connect the paper choice with structure, printing and finish. A loose swatch is useful for judging shade and touch; a printed, assembled sample reveals how the material behaves around corners, at glued joints and in the opening experience. For a carrying bag, evaluation centers on the loaded assembly. For a gift box, it includes the wrap, lid fit and product support. These comparisons help establish where a stronger paper, a different board or a simpler finish will contribute most.

When the brown tone and texture are central to the design, an agreed physical reference gives production a clearer target than a description such as “natural kraft.” The material specification and approved sample can bring that visual intention together with the construction and performance the product needs.

If you have a product or a reference look in mind, talk with us about your kraft packaging. Product dimensions and weight, a visual reference, the expected quantity and handling conditions give us a useful starting point for developing suitable materials, structures and sample options.