Kraft Paper is one of the most commonly used packaging and industrial materials worldwide, known for its natural strength, flexibility, and recyclability. However, whether kraft paper functions as a vapor barrier depends on its composition and whether it has been coated or laminated with moisture-resistant layers.
This article explains what kraft paper is, what materials are used to make it, its properties and advantages, and whether it can act as an effective vapor barrier.

1. What Kraft Paper Is

Kraft paper is a high-strength paper produced through the kraft pulping process, where wood fibers are chemically treated to remove lignin and impurities, leaving behind long cellulose fibers. These long fibers create a dense, durable sheet with high tear and burst resistance.

Kraft paper can be natural brown (unbleached) or white (bleached), and it comes in different weights and finishes for use in packaging, wrapping, insulation, and industrial lining applications.

Common Types of Kraft Paper

The kraft paper shown in the images includes both plain and laminated rolls, which can be customized in width and thickness according to user requirements.

2. What Materials Kraft Paper Is Made Of

Kraft paper is primarily composed of natural wood pulp fibers combined with small amounts of additives to enhance flexibility and durability. Depending on the application, it may include the following layers or treatments:

• Base Material: 100% virgin wood pulp or recycled pulp

• Lamination Material (optional): PE (polyethylene), aluminum foil, or wax

• Coatings: Water-resistant or vapor-resistant coatings depending on industry standards

For industrial applications like PE-laminated kraft paper, the paper is coated with a thin polyethylene film that enhances its water resistance and provides a partial vapor barrier. This combination of Paper and PE, as shown in the specification table, can be tailored through OEM/ODM customization for specific industries.

3. Is Kraft Paper a Vapor Barrier?

A) Uncoated Kraft Paper

Pure kraft paper is not a complete vapor barrier. While it offers some resistance to air and moisture vapor due to its fiber density, it is still porous enough to allow vapor transmission. It may absorb humidity and weaken under prolonged exposure to moisture.

Therefore, plain kraft paper alone cannot serve as an effective vapor barrier in applications such as insulation or food packaging.

B) Laminated or Coated Kraft Paper

When kraft paper is laminated with polyethylene (PE), aluminum foil, or wax, it can function as a vapor barrier.

• PE-laminated kraft paper provides moisture and vapor protection, ideal for packaging materials, insulation wraps, or composite linings.

• Aluminum-coated kraft paper offers the highest vapor and heat resistance, often used in building insulation, HVAC ducts, and reflective packaging.

Thus, whether kraft paper acts as a vapor barrier depends on its lamination structure—the base kraft layer provides mechanical strength, while the coating determines the level of vapor protection.

4. Characteristics and Advantages of Kraft Paper

A) High Mechanical Strength

Kraft paper has excellent tear and tensile resistance, making it ideal for heavy-duty wrapping, industrial rolls, and carton liners.

B) Eco-Friendly and Recyclable

Uncoated kraft paper is 100% recyclable and biodegradable, produced from renewable wood fibers. Even laminated versions can be made using recyclable PE coatings or water-based adhesives to reduce environmental impact.

C) Excellent Printability

The surface can be easily printed or customized with branding, labels, or instructions, which is beneficial for both consumer packaging and industrial labeling.

D) Customizable Width and Thickness

Manufacturers can customize roll width, thickness, and color according to customer requirements, ensuring compatibility with various production machines.

E) Versatile Functionality

By adjusting the coating or lamination, kraft paper can be adapted for moisture-proof, vapor-proof, or oil-resistant applications—making it suitable for packaging, construction, and electronics industries.

Summary

Kraft paper by itself is not a true vapor barrier, but when laminated or coated with PE, wax, or aluminum foil, it becomes a high-performance moisture and vapor-resistant material. Its versatility, strength, and eco-friendliness make it a staple choice across industries ranging from packaging to construction.

For manufacturers and converters, kraft paper offers a perfect balance of mechanical durability, environmental sustainability, and customization potential—especially when combined with functional coatings to meet vapor control requirements.