What is Kraft Paper?

Kraft paper is a durable, tan-colored paper made from wood fibers of coniferous trees. The process involves breaking wood into pulp, beating it to strengthen fiber bonds, adding sizing and dyes, and forming sheets on a papermaking machine. Named for its tan color and cowhide-like toughness, it's widely used in packaging,envelope paper, adhesive sealing paper, asphalt paper, cable protection paper, insulating paper, and more.

Kraft paper typically retains its natural tan color, making it suitable for bags, wrapping materials, and packaging.
● It can be classified according to the use:
Packaging kraft paper
Moisture-resistant kraft paper
Waterproof kraft paper
Process kraft paper
Proofing kraft paper
Rust-proof kraft paper
Insulating kraft board
Kraft stickers
● It can be divided according to the colour:
Natural kraft paper
Matte kraft paper
White kraft paper
Red kraft paper
Single-gloss kraft paper
Dual-color kraft paper
● It can be divided according to the material:
Recycled kraft paper
Kraft core paper
Virgin kraft paper
Rough-textured kraft paper
Waxed kraft paper
Wood-pulp kraft paper
Composite kraft paper

What Are the Advantages of Kraft Paper?

1. Smooth, Clean Surface: Neatly wound rolls with no more than 2 splices per roll.
2. Stable Heat Transfer: Uniform and consistent with moderate heat flow rate.
3. High Elasticity Under Heat & Pressure: Maintains flatness, significantly improving bonding quality and product yield.

Why is Kraft Paper Stronger Than Regular Paper?

The main reason is that kraft paper uses longer wood fibers. When cooking wood chips, it uses chemicals like caustic soda and sodium sulfide. These chemicals create gentler reactions, causing less damage to the fibers' natural strength. The resulting pulp forms paper with tightly bonded fibers, making it extra strong.

How to Distinguish Between Thickness and Grammage of Kraft Paper？

Grammage of kraft paper refers to its weight per square meter, measured in grams per square meter (g/m²).  Generally, higher grammage means thicker paper.  For example, 40-gram kraft paper is relatively thin, while 200-gram kraft paper is extremely thick.

So, how exactly can it be measured?

For professional measurement, tools like micrometers, calipers, or thickness gauges are used. There's also a calculation method: thickness and grammage are linked by a coefficient (Thickness / Grammage = Thickness Coefficient).  To find thickness: Grammage × Thickness Coefficient = Thickness.  To find grammage: Thickness / Thickness Coefficient = Grammage.
Additionally, in the paper industry, thickness is often measured in 'threads' (1 mm = 100 threads).  For example, 100g white kraft paper is about 13 threads (0.13mm).  Thicker kraft paper (higher grammage) is used for heavy-duty purposes like shipping boxes, while thinner varieties (lower grammage) are ideal for food packaging or book covers.