The Ultimate Guide to Wet Strength Agents

The Ultimate Guide to Wet Strength Agents
The Ultimate Guide to Wet Strength Agents



Wet strength agents are chemicals added to paper to improve its ability to resist water and maintain its mechanical properties and dimensional stability. These agents have become increasingly important in the paper industry as they enable producing high-quality paper products that can withstand moisture and automatic stress exposure.

Wet strength agents are polymers or cross-linking agents added to paper and paperboard products during manufacturing to improve their resistance to moisture. These compounds work by cross-linking the cellulose fibers in the paper, increasing its strength and stability. The most common wet-strength agents are urea/formaldehyde resins, melamine/formaldehyde resins, and polyamide-amine-epichlorohydrin (PAE) resins.

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Importance and Applications in the Paper Industry

The importance of wet strength agents lies in their ability to improve the quality and performance of paper products. For instance, they are crucial in producing tissue papers, where high wet strength is required to stay intact during use. Wet strength agents are also used in manufacturing paper labels, where the brands need to maintain their adhesion strength even when exposed to moisture. In addition, these agents enhance the durability of paper products used as packaging materials and prevent them from losing power when exposed to humidity or water.

Regulatory Framework and Non-Governmental Guidelines

Several agencies and organizations regulate the use of wet-strength agents in the paper industry. In the US, the Food and Drug Administration (FDA) regulates the use of these agents in food packaging materials. At the same time, the Environmental Protection Agency (EPA) sets standards for their environmental impact. The European Chemicals Agency (ECHA) also regulates the use of wet-strength agents in the European Union. Furthermore, several non-governmental organizations, such as the Forest Stewardship Council (FSC) and the Programme for the Endorsement of Forest Certification (PEFC), have established guidelines for sustainable forest management and the use of chemicals in the paper industry.

Types of Wet Strength Agents

Types of Wet Strength Agents

Wet Strength Resins

Wet-strength resins are synthetic polymers that are added to the paper pulp during the papermaking process to increase the wet strength of the paper. These resins typically contain reactive functional groups that can form covalent bonds with the cellulose fibers in the article, thereby creating a network of polymer chains that can withstand the disruptive forces of water. The most commonly used wet-strength resins include polyamides, polyacrylamides, polyvinylamines, and epichlorohydrin resins. These resins are widely used in producing tissue paper, paper towels, and food packaging materials that require high wet strength properties.

Dry Strength Additives

Dry strength additives are chemicals that improve paper’s mechanical strength in its dry state. These additives are added to the paper pulp before or after the addition of wet-strength resins, and their primary function is to increase the internal bond strength of the paper and prevent it from breaking or tearing under stress. The most commonly used dry-strength additives include cationic starches, carboxymethyl cellulose (CMC), and polyvinyl alcohol (PVA). These additives are used in various paper grades, including printing and writing papers, linerboards, and packaging papers.

Temporary Wet Strength Agents

Temporary wet strength agents, known as quick damp end additives, provide short wet strength to paper during papermaking. These agents are added to the paper pulp as a dilute solution. They are activated by the presence of water, which triggers a chemical reaction that forms a temporary network of hydrogen bonds between the cellulose fibers in the paper. The quick wet strength these agents provide dissipates over time and is gradually replaced by the permanent damp force imparted by damp strength resins. The most commonly used temporary wet strength agents include polyamidoamine epichlorohydrin (PAE) and polyamine-based products. These agents produce many paper grades, including tissue paper, filter paper, and packaging grades.

Mechanism and Benefits of Wet Strength Agents

Wet strength agents primarily work by cross-linking the cellulose fibers in paper. Cross-linking is a process whereby chemical bonds are formed between the cellulose fibers, making the threads more robust and rigid. Wet strength agents react with the cellulose fibers in the paper to form covalent bonds that increase fiber-to-fiber bonding and resistance to water. This chemical reaction leads to the improvement of paper strength and stiffness.

The use of wet-strength agents in paper production brings numerous benefits. Firstly, paper made with damp strength agents has a reduced tendency to tear when exposed to water. This makes it ideal for paper products that are likely to be exposed to moisture, such as paper towels and tissues. Secondly, wet strength agents also enhance the printability of paper. Paper prone to wrinkling and distortion during printing is less likely to do so when wet-strength agents are used. Lastly, paper made with damp strength agents has an increased shelf life due to its ability to resist aging. This makes it more suitable for archival purposes, such as bookbinding and library paper.

Popular Wet Strength Agents in the Paper Industry

Popular Wet Strength Agents in the Paper Industry

FennoStrength™ for High Wet Strength Efficiency

FennoStrength™ is a wet strength agent developed by Kemira Chemicals, a global chemical company specializing in water chemistry. FennoStrength™ is widely used in the paper industry because of its high damp strength efficiency. It works by providing enhanced bonding between fibers, which increases the strength of the paper when wet. FennoStrength™ has a reputation for being a reliable and high-performing product that offers better retention rates, higher wet power, and improved machine runnability. This wet-strength agent is formulated to work effectively across various paper grades, such as tissue, packaging, and printing paper.


METRIX™ ARMOR is another famous wet-strength agent widely adopted in the paper industry. Produced by Solenis, a chemical company focused on developing sustainable solutions for diverse sectors, METRIX™ ARMOR boasts unique qualities that set it apart from other wet-strength agents. For instance, it is formulated to provide maximum wet strength with minimal impact on paper quality, fiber strength, and machine runnability. Its superior performance is attributed to its molecular design, which enhances its penetration and bond formation capability. Additionally, METRIX™ ARMOR is cost-effective, biodegradable, and eco-friendly, making it an ideal option for companies seeking to reduce their environmental impact.


METRIX™ TITAN TECHNOLOGY is a revolutionary wet strength agent developed by Solenis. This technology leverages the power of advanced molecular design to deliver unmatched wet strength performance, ensuring that paper products retain their integrity even when exposed to water. METRIX™ TITAN TECHNOLOGY is an all-in-one solution that offers superior wet strength, improved machine runnability, higher retention rates, and excellent print quality, making it a beautiful choice in the paper industry. In addition, METRIX™ TITAN TECHNOLOGY is designed with sustainability in mind, making it environmentally friendly. It is free of formaldehyde, melamine, and other harmful substances, making it a safer option for use.

Environmental Considerations

Wet strength agents are one such consideration in the paper industry, as they play a significant role in manufacturing paper products. Using sustainable damp strength agents can minimize the negative impact of production on the environment, making it an important focus of many paper manufacturers today.

Sustainability and Wet Strength Agents

Sustainability is the ability to maintain or improve environmental, social, and economic well-being without compromising the ability of future generations to meet their needs. However, the traditional process of making wet strength agents involved using harmful chemicals that could cause significant environmental damage. As such, advances in technology and research have led to the development of more sustainable and environmentally friendly alternatives.

Efforts Towards Environmentally Friendly Wet Strength Solutions

The production of wet-strength agents that do not harm the environment is a challenge many paper manufacturers face today. Many mainstream wet-strength agents contain formaldehyde, a known carcinogen, and other hazardous chemicals that significantly negatively impact the environment. However, there has been a growing consciousness of the need for sustainable production of these agents in recent years. Some companies are developing alternative wet strength additives that are more eco-friendly, while others are working towards producing traditional types of wet strength agents more sustainably.

The Road to a Sustainable Future

While companies in the paper industry have made significant progress toward sustainable wet-strength solutions, many challenges still exist. Research and development efforts are ongoing to develop sustainable alternatives to traditional agents, and the industry is committed to finding eco-friendly solutions to improve the production process. In addition, consumers need to choose products made from environmentally friendly wet-strength agents. In this way, they can contribute to promoting a sustainable industry and minimize the negative impact of paper production on our planet.

A Call to Action for Environmental Conservation

As individuals, we can take several actions to minimize our environmental impact. This includes opting for paper products made from sustainable wet-strength agents and reducing our reliance on single-use plastic. We can also participate in community efforts to reduce carbon footprint and promote eco-friendly practices. Doing so can contribute to a better future for ourselves and future generations. It is time for everyone to act responsibly, choose sustainable products, and take steps to make the world a better place.



Q: How do wet strength agents improve the wet strength of paper?

A: Wet strength agents enhance the mechanical properties of paper products by providing strength development in wet and dry conditions.

Q: What are some standard terms associated with wet-strength agents?

A: Some standard terms associated with wet strength agents include additive, strength additive, resin, strength resin, wet strength resin, dry strength, paper product, pae resin, tissue paper, paper production, dry strength additives, wet strength chemical, paper making, wet strength agents for tissue, agents for tissue and paper, tissue and paper production, temporary wet strength, and agent for paper.

Q: How do wet strength agents affect the level of damp strength in paper?

A: Wet strength agents increase the wet strength in the paper, making it more resistant to tearing or breaking when exposed to moisture.

Q: Are wet strength agents only used for tissue and paper production?

A: No, wet strength agents are also used in other industries that utilize paper, such as packaging materials and sanitary products.

Q: What is the difference between wet strength and dry strength?

A: Wet strength refers to the power of paper when exposed to moisture, while dry management refers to the ability to form under dry conditions.

Q: What other benefits of using wet-strength agents in papermaking?

A: In addition to improving the wet strength of paper, wet strength agents can also enhance the printability, handling, and overall quality of the finished piece.

Q: How are wet strength agents applied in the papermaking process?

A: Wet strength agents are typically added to the pulp during the papermaking process, either as a part of the initial pulp mixture or as a separate treatment step.

Q: What examples of wet-strength agents are used in the papermaking industry?

A: Some examples of wet strength agents used in the papermaking industry include synthetic resins, such as polyamide epichlorohydrin (PAE) resin, and other chemical compounds specifically designed to improve the wet strength of paper.

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