How to Match Sizing Agents to Paper Grades and Drying Conditions

How to Match Sizing Agents to Paper Grades and Drying Conditions

Choosing a sizing agent is not a one-size-fits-all decision. The right product depends on the paper grade being made, the fiber source, the pH environment, the drying capacity, the storage climate and the end-use requirement. A styrene-acrylic surface size that performs well on recycled corrugated medium may not solve linting on a high-speed offset printing paper line. This guide uses a scenario-based selection approach to help paper mill technical teams, procurement managers and distributors compare paper sizing agents by production situation rather than by generic type.

Qingzhou Jinhao New Material Co., Ltd., branded as JHDA, is a papermaking chemical manufacturer founded in 2005 and located in Qingzhou City, Shandong Province, China. JHDA develops, produces and supplies sizing agents and other papermaking fine chemicals to paper mills primarily in Asia, Africa and South America. Its sizing portfolio includes AKD internal sizing emulsion, AKD surface sizing emulsion, styrene-acrylic surface sizing agents, moisture-resistant sizing agents and composite surface sizing agents.

Why Sizing Agent Selection Is a Production-Scenario Problem

Sizing agents control how much water or ink penetrates into the paper sheet. On a production scale, however, the chemistry is interacting with a specific furnish, machine and finishing process. For example, a wet-end AKD emulsion can build hydrophobic bonds with fiber in a neutral papermaking system, but internal sizing may be less efficient when the mill relies on high levels of recycled fiber and closed white-water systems. Surface-applied sizing places the active material directly onto the formed sheet and can reduce losses that occur in wet-end circulation.

The financial impact is also significant. According to Dataintelo, the global paper sizing agent market was valued at approximately USD 3.8 billion in 2025. SNS Insider reports that synthetic sizing agents, including AKD and ASA, held a 54.5% market share in 2024, while Asia Pacific accounted for 42.3% of revenue according to Dataintelo. With this wide range of available chemistries, the practical question for a mill is: which sizing agent fits my line, my furnish and my customer requirement?

Sizing Chemistry Options: A Short Profile of JHDA Products

JHDA’s sizing range covers internal and surface application routes. The main chemistries are AKD emulsion, styrene-acrylic emulsion (SAE) and a composite AKD/SAE system. The following product profiles reflect JHDA’s documented product position in the market.

JH-103 AKD Internal Sizing Agent

JH-103 is an AKD internal sizing emulsion with 12.5% to 25.0% solid content, a pH of 2.0 to 5.0 and cationic charge. It is designed for neutral and alkaline papermaking systems. Its active alkyl ketene dimer reacts with cellulose fiber to form a permanent waterproof barrier. JH-103 is suitable for cultural paper, copy paper, packaging board and molded pulp products where internal water resistance is required.

JH-200 Surface AKD Sizing Agent

JH-200 is a starch-compatible AKD surface sizing emulsion supplied at 20.0% or 30.0% solid content. It is applied at the size press and can be mixed with industrial starch. Because the AKD reactive component is placed on the paper surface, JH-200 avoids the effective AKD losses found in white-water circulation during internal dosing. The sizing effect is finalized after the paper passes through the drying cylinder, which shortens the curing wait required with traditional AKD products.

JH-325 Anionic Surface Sizing Agent

JH-325 is an anionic styrene-acrylic surface sizing agent with 25.0% solid content. It is intended for printing and writing paper, office paper and book paper. The anionic styrene-acrylic copolymer forms a continuous film with starch and improves dry and wet surface strength. It also controls ink penetration and supports high-speed offset printing. JH-325 can work with acidic alum-based systems as well as neutral papermaking systems.

JH-611 Surface Strength Sizing Agent

JH-611 is a cationic styrene-acrylic surface sizing agent at 30.0% solid content. It forms a cross-linked waterproof film when blended with starch. JH-611 can replace wet-end internal sizing agents because the hydrophobic effect develops after drying, with no curing time. This product is positioned for corrugated paper, boxboard and recycled packaging grades that require immediate water resistance and improved ring crush stiffness.

JH-600 Moisture-Resistant SAE Surface Sizing Agent

JH-600 is a styrene-acrylic based moisture-resistant surface sizing agent at 30.0% solid content. It is designed to address moisture reversion, damp collapsing and property loss in rainy seasons, cold storage or long-distance maritime transport. JH-600 maintains hydrophobic performance even after the paper is exposed to humid conditions for long periods. It is compatible with common starch and can fully replace internal sizing for many packaging applications.

JH-WH3364 Composite Surface Sizing Agent

JH-WH3364 is a composite surface sizing agent with 25.0% solid content. It combines the reactive waterproof chemistry of AKD with the film-forming toughness of styrene-acrylic resin. The SAE component fixes the sizing effect immediately after drying, while the AKD component provides long-term hydrophobic bonding. This composite route reduces the need to purchase and dose separate AKD and SAE products.

Step-by-Step Scenario-Based Selection Process

The following five-step selection process can help a project team turn a vague chemical request into a measurable sizing decision.

Step 1: Define the Final Paper or Board Use Scenario

Identify the finished product that will be sold or converted. Corrugated paper, carton board, printing writing paper, pulp molded products and food-grade packaging paper each place different demands on the sizing chemistry. A carton board line that must pass box compression tests in a humid market is not operating with the same priority as a digital printing paper line that needs clean surface picking behavior.

Step 2: Review the Furnish and Machine Environment

Check whether the mill uses recovered fiber, virgin wood pulp or a blend. High levels of recycled fiber can bring impurities and conductivity fluctuations that affect sizing response. Also record whether the wet end is acidic, neutral or alkaline. JHDA formulates according to the customer’s recycled pulp or virgin wood pulp and the actual paper machine operating parameters, which helps to reduce chemical consumption and production cost.

Step 3: Define the Target Test Values

The relevant verification targets usually include Cobb water absorption, ring crush strength, bursting strength, paper brightness, fiber retention and overall machine runnability. For a carton converting mill, ring crush and moisture resistance may be critical. For a printing mill, surface strength, pick resistance and ink holdout often dominate.

Step 4: Select Internal Sizing, Surface Sizing or a Combination

If the base sheet needs bulk waterproofing throughout the sheet, an AKD internal sizing agent such as JH-103 is a practical starting point. If the mill wants rapid cure, high active-substance utilization and lower alteration to the wet end, surface sizing with an SAE, AKD surface emulsion or composite emulsion may be more appropriate. Many mills use an internal sizing agent for base water resistance and a surface sizing agent for printability and top-layer strength.

Step 5: Conduct a Controlled Machine Trial

Free trial samples and pre-shipment laboratory testing are part of JHDA’s sampling process. A controlled trial should compare the reference chemistry with the candidate sizing product using a standard size-press starch dose and standard wet-end settings. Because surface sizing systems can often be added in the existing surface sizing tank without changing the pulp formula, old production lines can evaluate the product with low conversion cost.

Use Cases by Paper Grade and Production Scenario

Recycled Corrugating Medium and Boxboard

For corrugated medium and recycled boxboard, the main concerns are water pickup, ring crush retention and moisture reversion. JHDA’s JH-611 surface strength sizing agent is a cationic styrene-acrylic copolymer that blends with starch and forms a cross-linked waterproof film. It does not require the curing period normally associated with internal AKD sizing, so the paper can be rolled and delivered immediately after the dryer. JH-611 also improves ring crush stiffness and reduces breakage during creasing and die-cutting.

Printing and Writing Paper with High-Speed Offset or Digital Printing

Printing and writing paper requires a surface that is smooth, pick-resistant and compatible with ink. JH-325 is an anionic styrene-acrylic surface sizing agent that strengthens the paper surface and reduces linting, picking and blanking faults during high-speed rotary printing. It also controls ink bleeding and penetration, resulting in clearer text and more uniform color. If the base paper needs internal water resistance in a neutral system, JH-103 AKD can be added in the wet end and JH-325 applied at the size press.

Corrugated Cartons for Rainy Season or Export Humidity

When finished cartons are stored in high humidity, transported across climate zones or shipped by sea, ordinary surface sizing may lose effectiveness over time. JH-600 is a moisture-resistant surface sizing agent developed to prevent paper softening and box collapse caused by moisture reversion. It has good compatibility with starch and can be used as a full substitute for internal sizing products when the production goal is fast, durable anti-moisture performance. This product maintains stable hydrophobic performance in humid environments and helps finished board retain ring crush strength and surface rigidity.

Cartons Requiring Immediate Cutting, Scoring or Die-Cutting

If a board mill needs both waterproof performance and high surface stiffness without waiting days for AKD cure, a composite surface sizing agent is a relevant choice. JH-WH3364 combines AKD and styrene-acrylic resin in one product. The SAE component establishes surface strength immediately after drying, while the AKD component reacts with cellulose fiber to provide long-term hydrophobic properties. This can simplify chemical dosing because the mill no longer purchases and stores separate AKD and SAE products.

Molded Pulp Products with Waterproof Demand

Molded pulp packaging and disposable tableware are often produced from recycled fiber and require controlled water pickup. JH-103 AKD internal sizing emulsion is designed for molded pulp products with waterproof requirements. Because JH-103 is a liquid product, it can be metered directly into the pulp pipeline and works with the neutral and alkaline conditions typical of molded pulp production.

Sizing Agent Scenario Selector

Implementation Considerations for a Sizing Change

A sizing agent change is not only a chemistry decision; it requires verification of storage, dosing and downstream operations. Liquid sizing emulsions should be stored according to their documented shelf life. Typical process requirements include environmental compliance with low VOC and no APEO/NPEO, formula compatibility, salt and high-temperature resistance, and long-term storage stability. JHDA designs chemical formulations according to each customer’s pulp composition and actual paper machine parameters, and its technical field team is available for on-site machine debugging.

For overseas paper mills, JHDA can supply trial samples before bulk ordering. The company’s standard MOQ is 1 metric ton, and standard production lead time is four working days. Export documentation such as TDS, MSDS, certificate of origin and dangerous goods transport certification can be arranged according to destination requirements. For a large-volume project, JHDA has supported supply volumes of more than 100,000 metric tons across more than twenty countries, including full-series papermaking functional additives and wastewater treatment chemicals for containerboard, corrugated paper, food-grade packaging, cultural printing and tissue grades.

In one documented case involving full-series papermaking chemicals, the central issue was chemical management complexity. JHDA provided a one-stop procurement solution by supplying customized papermaking chemical formulations that matched diverse production demands. This reduced the number of chemical suppliers needed and simplified factory management.

Frequently Asked Questions

Conclusion

Selecting a paper sizing agent should follow the production scenario: the grade being made, the furnish being used, the environmental conditions and the measurable paper properties that must be delivered. Internal AKD sizing is useful when bulk water resistance is required. Surface sizing with SAE, AKD or composite products becomes attractive when a mill needs faster cure, better surface strength and lower wet-end disturbance. JHDA’s range from JH-103 AKD to JH-325, JH-611, JH-600 and JH-WH3364 provides documented options for internal, surface, anti-humidity and composite sizing applications.