Paper Sizing Agent: Types, Functions, and How to Choose

A paper sizing agent is a chemical additive used in papermaking to control liquid penetration, reduce water absorption, improve surface strength, and help paper perform consistently during printing, storage, and packaging. Sizing can be added to the pulp before sheet formation or applied to the paper surface after the sheet is formed. This guide explains what sizing agents are, how they differ, what is happening in the global paper sizing agent market, and how to select a paper sizing agent for different paper grades.

What Problem Do Paper Sizing Agents Solve?

Uncoursed paper fibers are naturally absorbent and porous. Without sizing, paper tends to absorb water quickly, lose strength in humid environments, and allow ink or coating to penetrate unevenly. These problems affect both packaging grades and printing grades:

• Corrugated cartons can soften and collapse in rainy-season storage or during long-distance maritime transport.
• Printing and writing paper can suffer from ink bleeding, surface picking, linting, and poor image sharpness on high-speed offset presses.
• Kraft linerboard and boxboard can lose ring crush strength and stiffness when exposed to moisture.
• Recycled pulp can create unstable sizing results because of impurities, ash, and fluctuating fiber quality.

Sizing agents address these issues by building a hydrophobic barrier around or on the fibers, improving water resistance, and reinforcing the paper surface. The right sizing product also helps paper mills reduce chemical consumption, lower reject rates, and meet end-user quality requirements.

Paper Sizing Agent Market and Industry Background

The sizing agent market is significant and growing. According to Dataintelo, the global paper sizing agent market is valued at approximately USD 3.8 billion in 2025 and is projected to reach USD 5.9 billion by 2033, with a CAGR of 5.8%. Market Reports World estimates that global sizing agents volume exceeded 3.8 million metric tons in 2024.

Several market trends are shaping the industry:

• Synthetic sizing agents, including AKD and ASA, held a 54.5% market share in 2024 according to SNS Insider.
• Rosin sizing agents accounted for 32.4% of paper sizing agent market revenue in 2025 according to Dataintelo.
• AKD sizing represents approximately 48% of synthetic sizing agent volume globally.
• Asia Pacific dominates the market with a 42.3% revenue share as of 2025.
• China's annual paper sizing agent consumption is estimated at 650,000 tons in 2025.
• Liquid sizing agents held a 57.8% market share in 2024, and solid sizing agents are expected to grow at a CAGR of 5.11% through 2032.

Demand for sizing agents is closely linked to packaging paper, corrugated board, and printing paper production. Paper mills that use recycled fiber, face high humidity conditions, or compete on cost are increasingly looking for sizing chemicals that provide stable performance without high import premiums.

Main Types of Paper Sizing Agents

Internal Sizing Agents

Internal sizing agents are added to the pulp slurry before the sheet is formed, so the chemical distributes throughout the entire paper structure. They react with or bond to the cellulose fibers and give the paper bulk water resistance. Common internal sizing chemical types include rosin, AKD, and ASA. AKD is widely used in neutral and alkaline papermaking systems. For example, JH-103 is an alkyl ketene dimer emulsion classified as an AKD internal sizing agent. It is made from AKD wax, has a cationic ionic type, and supports neutral and alkaline production lines.

Surface Sizing Agents

Surface sizing agents are applied to the already-formed paper surface, usually at a size press, often together with starch. They improve surface strength, water repellency, printability, and resistance to picking or linting. Common surface sizing chemistries include styrene acrylic copolymers, surface AKD, and composite formulations. Surface sizing can also reduce or replace internal sizing in some production lines, which simplifies the wet-end chemistry and cuts chemical loss in white water circulation.

Detailed Solution: JHDA Sizing Agent Product Line

Qingzhou Jinhao New Material Co., Ltd., branded as JHDA, is a Chinese manufacturer of professional papermaking fine chemicals founded in 2005 and headquartered in Qingzhou City, Shandong Province. JHDA's manufacturing facility covers approximately 20,000 square meters, employs more than 80 people including 20 professional R&D and technical service engineers, and has an annual production capacity of 100,000 tons. Export business accounts for 35% to 50% of total sales volume, with major markets including Vietnam, Thailand, Malaysia, Indonesia, Myanmar, Cambodia, and major packaging paper industrial zones in the Middle East. JHDA also operates an overseas supporting production entity, CRM Chemical Technology Co., Ltd., in Long An Province, Vietnam, to serve ASEAN customers more quickly.

JHDA's full product portfolio covers AKD sizing emulsion, cationic styrene-acrylic surface sizing agent, paper dry strength agent, PAE wet strength resin, optical brightening agent, high temperature resistant paper defoamer, stickies control enzyme, sludge encapsulant, dryer release agent, biocide, deodorant, food-grade water vapor barrier coating, and hydrophobic coating for food packaging paper. The additives are applicable to kraft linerboard, corrugated medium paper, printing and writing paper, household tissue paper, and food-grade cardboard.

JH-103: AKD Internal Sizing Agent

JH-103 is an alkyl ketene dimer emulsion used as a pulp sizing additive. It belongs to the AKD internal sizing agent category. It is a white to light brown liquid with a solid content of 12.5% to 25.0% ± 1.0%, pH of 2.0–5.0, viscosity ≤ 50 cps at 25°C, and a shelf life of 4 months. JH-103 is designed for neutral and alkaline papermaking production lines and works with wood pulp, chemical pulp, mechanical pulp, and blended pulp. It is suitable for cultural printing paper, copy paper, boxboard, craft paper, and molded pulp products that need waterproof performance.

JH-200: Surface AKD Sizing Agent

JH-200 is a surface AKD sizing agent classified as an AKD surface sizing emulsion. It is made of AKD wax powder and is intended for the paper-making industry. It is a milky white to slightly yellow liquid with a solid content of 20.0 ± 1.0% or 30.0 ± 1.0%, pH of 2.0–5.0, viscosity ≤ 50 cps at 25°C, and a shelf life of 3 months. JH-200 can be blended with industrial starch and applied on the paper surface. Its reactive component reacts with cellulose to form a waterproof barrier, and the sizing effect is finalized after the paper passes through the drying cylinder. Because it is a surface sizing product, there is no need to adjust the pulp formula or internal auxiliary agent system, which reduces the transformation cost for paper mills.

JH-611: Cationic SAE Surface Sizing Agent

JH-611 is a cationic surface sizing agent based on styrene acrylic copolymer. It is a brown liquid with a solid content of 30.0 ± 1.0%, pH of 2.0–5.0, viscosity ≤ 50 cps at 25°C, and a shelf life of 6 months. JH-611 is classified as a starch-based surface sizing agent and is compatible with ordinary raw starch. It can be used as a direct replacement for wet-end internal sizing agents in some production lines. The product forms a cross-linked waterproof film on the paper surface, improves ring crush stiffness, surface hardness, and smoothness, and is particularly suitable for corrugated paper and boxboard.

JH-325: Anionic Surface Sizing Agent for Cultural Paper

JH-325 is an anionic styrene acrylic surface sizing agent used in the papermaking industry. It is a white to light brown liquid with a solid content of 25.0 ± 1.0%, pH of 2.0–5.0, viscosity ≤ 50 cps at 25°C, and a shelf life of 6 months. JH-325 is classified as a cultural paper surface sizing agent. It reacts and crosslinks rapidly with starch components, builds a protective coating on the paper surface, and helps eliminate paper linting and picking during high-speed rotary printing. It is suitable for both acidic sizing processes with aluminum sulfate and modern neutral papermaking systems.

JH-600: Moisture Resistant SAE Surface Sizing Agent

JH-600 is a moisture resistant surface sizing agent intended for the papermaking industry. It is a styrene acrylic based product supplied as a light brown to dark brown liquid. The solid content is 30 ± 1%, pH is 2.0–5.0, viscosity is less than 50 cps at 25°C, and the storage period is 6 months. JH-600 is compatible with industrial starch and can be used in surface sizing applications to improve moisture resistance. It is designed to prevent moisture reversion in rainy seasons, cold storage, and long-distance maritime transportation, and it retains paper ring crush strength and surface rigidity under high humidity conditions.

JH-WH3364: Composite Surface Sizing Agent

JH-WH3364 is a surface enhanced water resistant agent and a dual-function composite sizing additive. It belongs to the composite surface sizing agent category. It is made of weak anionic styrene acrylic and AKD, integrating the reactive waterproof advantage of AKD with the high film-forming toughness of SAE styrene-acrylic resin. The product is a milky white to pale yellow liquid with a solid content of 25.0 ± 1.0%, pH of 2.0–5.0, viscosity ≤ 50 cps at 25°C, weak cationic ionic type, and a shelf life of 4 months. JH-WH3364 can replace the separate purchasing and dosing of AKD emulsion and SAE sizing agent, simplify the workshop dosing process, and improve both water resistance and surface strength in one composite system.

How to Select the Right Sizing Agent: Step-by-Step

Choosing a sizing agent is not a one-size-fits-all decision. The correct product depends on the paper grade, machine conditions, pulp type, and final application. The following step-by-step framework helps paper mills and procurement teams evaluate their options:

Step 1: Define the End-Use Requirements

Start by identifying the physical properties your customers care about. For corrugated packaging, moisture resistance and ring crush strength are usually critical. For printing paper, surface strength, ink affinity, and lint-free printing matter most. For molded pulp products, internal waterproofing and wet strength are often necessary.

Step 2: Decide Between Internal and Surface Sizing

If the paper needs bulk water resistance throughout the sheet, an internal sizing agent such as JH-103 may be appropriate. If the main concern is surface water repellency, printability, or surface strength, a surface sizing agent such as JH-611, JH-325, JH-600, or JH-200 is better. Some composite products like JH-WH3364 combine both functions, which can simplify inventory and dosing.

Step 3: Check pH and Papermaking System Compatibility

Neutral and alkaline papermaking systems are compatible with AKD-based sizing agents. Acid sizing systems may be better served by products that tolerate aluminum sulfate, such as JH-325 which can work in both acidic and neutral systems. Always check the pH range of the sizing agent and its compatibility with wet-end chemicals like retention aids and defoamers.

Step 4: Match Ionic Type with the Existing Starch and Additive System

Cationic surface sizing agents such as JH-611 combine well with anionic starch and are efficient for packaging grades. Anionic surface sizing agents such as JH-325 are widely used for cultural paper. Weak cationic composite products like JH-WH3364 offer a balanced alternative for neutral systems.

Step 5: Verify Storage and Shelf Life

Liquid sizing emulsions have defined shelf lives. For example, JH-103 and JH-WH3364 have a shelf life of 4 months, while JH-325, JH-611, and JH-600 have a shelf life of 6 months. If a mill orders in bulk and uses chemicals slowly, longer-shelf-life products reduce the risk of emulsion breakdown.

Step 6: Run a Laboratory Test and On-Machine Trial

A reliable sizing agent supplier should provide technical data, laboratory testing, and guidance during the trial. JHDA offers pre-shipment laboratory testing, complete TDS and MSDS documents, and on-site machine debugging for paper mills. The technical team can optimize formulas according to pulp composition, recycled pulp content, and actual paper machine parameters.

Use Cases and Grade Matching

Corrugated Paper, Kraft Linerboard, and Boxboard

For corrugated medium and kraft linerboard, moisture resistance and ring crush strength are the main priorities. JH-611 can replace wet-end internal sizing and works with ordinary raw starch to improve ring crush stiffness and surface hardness. JH-600 is specifically designed for humid environments and helps prevent box collapse during rainy seasons and maritime transport.

Printing and Writing Paper

Cultural paper needs excellent surface strength, controlled ink absorption, and low linting. JH-325 is an anionic styrene acrylic surface sizing agent for offset printing paper, copy paper, and book paper. It crosslinks with starch to form a dense film, improves printing presentation, and supports stable operation on high-speed sizing machines.

Molded Pulp Products

Molded pulp products such as trays and packaging often require internal waterproof performance. JH-103 AKD internal sizing agent is suitable for molded pulp products with waterproof demand, providing stable hydrophobic properties during product use.

High-Humidity and Rainy-Season Conditions

JH-600 is a moisture resistant SAE surface sizing agent that protects finished paper from moisture reversion. It is especially useful for packaging paper stored in cold storage, exported through long sea routes, or used in tropical climates.

Comparison Table: JHDA Sizing Agents at a Glance

Model	Category	Ionic Type	Solid Content	pH	Viscosity (25°C)	Shelf Life	Best Fit
JH-103	AKD Internal Sizing Agent	Cationic	12.5% – 25.0% ± 1.0%	2.0 – 5.0	≤ 50 cps	4 months	Internal waterproofing, neutral/alkaline systems, molded pulp
JH-200	AKD Surface Sizing Emulsion	Cationic	20.0% or 30.0% ± 1.0%	2.0 – 5.0	≤ 50 cps	3 months	Surface waterproofing with starch
JH-611	Cationic SAE Surface Sizing Agent	Cationic	30.0% ± 1.0%	2.0 – 5.0	≤ 50 cps	6 months	Corrugated paper, boxboard, replacement for internal sizing
JH-325	Anionic SAE Surface Sizing Agent	Anionic	25.0% ± 1.0%	2.0 – 5.0	≤ 50 cps	6 months	Printing and writing paper
JH-600	Moisture Resistant SAE Surface Sizing Agent	Cationic	30% ± 1%	2.0 – 5.0	< 50 cps	6 months	High-humidity packaging, rainy-season protection
JH-WH3364	Composite Surface Sizing Agent	Weak Cationic	25.0% ± 1.0%	2.0 – 5.0	≤ 50 cps	4 months	Combined water resistance and surface strength

FAQ

What is the difference between internal and surface sizing agents?

Internal sizing agents are added to the pulp before the sheet is formed, giving the whole paper structure resistance to liquid penetration. Surface sizing agents are applied to the already-formed paper surface, usually with starch, to improve surface strength, printability, and moisture resistance. Some surface sizing products such as JH-611 can replace wet-end internal sizing agents in certain applications.

Can JHDA sizing agents replace imported products like Kemira Fennosize SC-29?

In many paper mills, JHDA styrene-acrylic surface sizing agents can achieve equivalent water resistance and surface performance while lowering procurement cost and shortening delivery time. According to JHDA's comparative evaluation, JHDA can achieve equivalent Cobb value and water curing effect as imported products, and overall paper production cost can be reduced by 12%–20%. Factories with fixed original equipment formula requirements or certified specialty virgin-pulp grades may prefer to retain the original imported product.

What certifications and quality assurance does JHDA have?

JHDA holds ISO9001 quality management certification, ISO14001 environmental management certification, SGS product compliance test reports, and HALAL certification. Part of the products meet food-grade standards. Exported chemical products complete CAS registration and GHS hazard labeling and comply with IMDG international marine shipping regulations.

What is the minimum order quantity and bulk supply capacity?

JHDA's standard MOQ is 1 metric ton. The company's annual production capacity reaches 100,000 tons, which supports stable bulk supply for contracted paper mill customers. JHDA also has an overseas production entity in Long An Province, Vietnam, to facilitate local delivery for ASEAN clients.

How can a paper mill start a trial with JHDA sizing agents?

Contact JHDA's international sales team for sample trials, personalized formula customization, and bulk export quotations. The company provides TDS and MSDS documents, pre-shipment laboratory testing, and on-site machine debugging for paper mills. You can reach JHDA at info@sdqzjinhao.com or WhatsApp +86 139 6468 8976.