PAM in Paper Making: Retention & Drainage Guide

Polyacrylamide (PAM) in paper making is a cationic polymer used as a retention aid, drainage aid, and dry strength agent to improve fiber retention, machine speed, and paper quality. According to TAPPI (Technical Association of the Pulp and Paper Industry), over 85% of modern paper mills worldwide use some form of PAM in their wet-end chemistry.

At our Zhengzhou factory, we supply paper-grade PAM to mills across Asia, South America, and the Middle East — over 5,000 tons/year specifically for paper applications. Here is how it works and how to select the right grade.

PAM Applications in Paper Making

Polyacrylamide serves five distinct functions in paper manufacturing, each requiring different molecular weight and charge density specifications. The table below summarizes the key parameters based on our factory's technical data from supplying 200+ paper mills since 2009.

Retention Aid: Keeping Fines on the Sheet

A PAM retention aid is a cationic polyacrylamide that bridges fine fibers and filler particles to the paper sheet, preventing them from passing through the forming wire into white water. This is the single most impactful wet-end additive for reducing raw material loss.

In the wet end of a paper machine, fine fibers, fillers (calcium carbonate, kaolin), and fines pass through the wire and end up in white water. This wastes raw materials and loads the white water treatment system.

CPAM as a retention aid bridges between fiber surfaces and fine particles, keeping them on the forming wire. Based on our testing across 200+ mill installations, a well-optimized retention program improves first-pass retention from 60-70% to 85-95%, reducing raw material loss by 15-25% and saving $50,000-200,000/year for a typical 200 TPD mill.

For retention aid applications, we recommend CPAM with 20-50% charge density and 10-15M molecular weight. Higher charge density improves retention of anionic fines; higher MW improves bridging but can cause flocculation problems if overdosed.

Drainage Aid: Faster Dewatering on the Wire

A PAM drainage aid is a medium-molecular-weight cationic polyacrylamide (8-12M Da) that flocculates fine particles blocking the forming wire, allowing water to drain 10-20% faster and enabling 5-15% higher machine speed.

Drainage rate on the forming wire determines machine speed. Slow drainage limits production. CPAM improves drainage by flocculating fine particles that would otherwise block the wire, allowing water to drain faster.

For drainage aid, use CPAM with 30-60% charge density and 8-12M molecular weight. The higher charge density handles the anionic trash in modern recycled fiber furnishes. Lower MW produces smaller, denser flocs that drain faster than the large flocs from high-MW polymer.

Typical improvement: 10-20% increase in drainage rate, allowing 5-15% increase in machine speed.

Dry Strength Agent

PAM can also improve paper strength by forming hydrogen bonds with cellulose fibers. This application uses low molecular weight CPAM (1-3M Da) at higher dosage (5-15 kg/ton paper).

The low MW polymer penetrates the fiber network and forms bonds at fiber-fiber contact points. Typical improvement: 10-20% increase in tensile strength, 15-25% increase in burst strength.

This is particularly valuable for recycled fiber grades where fiber quality is lower and strength is harder to achieve.

White Water Treatment

Paper mill white water contains suspended fibers, fillers, and organic matter. Before discharge or reuse, it must be clarified. CPAM with 40-70% charge density effectively flocculates these materials for removal by dissolved air flotation (DAF) or settling.

Dosage: 2-8 kg/ton dry solids, depending on white water quality. Our CPAM for white water treatment is the same grade used for municipal sludge dewatering — high charge density, medium molecular weight.

Managing Anionic Trash

Modern paper mills use increasing amounts of recycled fiber, which introduces anionic trash — dissolved and colloidal substances (DCS) that consume cationic polymer and reduce its effectiveness.

High anionic trash demands higher charge density CPAM (50-70%) or the addition of a cationic coagulant (polyDADMAC or alum) before PAM dosing. We can help you optimize the coagulant-flocculant combination for your specific furnish.

PAM Behaves Differently in Each Paper Grade

The "use CPAM at 0.5 kg/ton" answer hides a lot of variation. The same retention aid that works beautifully on packaging board can foul a tissue machine within hours. Per Confederation of European Paper Industries (CEPI) wet-end chemistry surveys, dosage and grade selection vary by 3-5x across paper categories. Here is how we steer customers across the main grades:

• Newsprint and SC paper — high mechanical pulp content, heavy anionic trash from groundwood. Use medium-charge CPAM (30-40%), MW 8-10M, dose 0.4-0.7 kg/ton. Higher MW gives big flocs that hurt formation on fast machines.
• Fine paper (woodfree printing/writing) — high filler load (PCC, GCC up to 25-30%), low DCS. Use medium-MW CPAM (10-12M) at 30-50% charge, dose 0.3-0.6 kg/ton. Often paired with bentonite microparticle for better formation.
• Packaging board (testliner, fluting, kraft) — heavy recycled fiber, very high anionic trash. Use high-charge CPAM (50-70%), MW 6-10M, dose 0.6-1.2 kg/ton. The high charge consumes anionic trash before bridging — without it, the polymer just dissolves into the white water.
• Tissue and towel — short fiber, no filler, very sensitive to flocculation. Use low-MW CPAM (3-5M) at 15-25% charge, dose 0.2-0.5 kg/ton. Higher MW or charge causes spotting and stiffness.
• Specialty (filter paper, label, decor) — very specific formation requirements. We custom-blend MW and charge density per machine; no standard recipe.

We have shipped to mills running every one of these grades. The single most common failure we see at new accounts is using packaging-board CPAM (high charge, high dose) on a fine paper machine — the operator complains of "spots" and "stiff sheet" and blames the polymer, when the real issue is wrong grade selection.

White Water Loop: Where the Real Money Hides

First-pass retention numbers get a lot of attention, but the white water loop is where most paper mills actually lose value. A 200 TPD mill with 60% first-pass retention loses 80 ton/day of fiber and filler into white water. Even with 95% recovery in the save-all and DAF, that is still 4 tons/day going to the WWTP — about $200,000/year in raw material at typical prices.

Three white water management practices pay back fastest:

• DAF with high-charge CPAM (50-70%) at 2-5 kg/ton dry solids — captures fines and fillers before they hit the WWTP. The recovered solids go straight back to the broke chest.
• Conductivity monitoring on the short loop — when conductivity creeps from 1,500 to 3,000+ µS/cm, retention aid effectiveness drops sharply. A controlled bleed (5-10% of white water to the long loop) prevents this.
• Microparticle programs — a CPAM/bentonite or CPAM/silica combo creates a more shear-resistant retention system. First-pass retention typically rises from 70% to 88-92% on fine paper machines.

PAM Combinations with Other Wet-End Chemicals

CPAM rarely runs alone. The right combination with other wet-end chemicals can cut total polymer cost by 20-30% versus PAM-only dosing. Some combinations that work in our installed base:

• PolyDADMAC + CPAM — coagulant first to neutralize anionic trash, then CPAM for bridging. Works well in OCC/recycled furnishes. PolyDADMAC at 1-3 kg/ton, CPAM dose drops to 0.3-0.5 kg/ton.
• Alum + CPAM — traditional acid sizing systems. Alum at 5-10 kg/ton fixes ASA/AKD sizing and creates anchor sites for CPAM. Best below pH 7.
• Cationic starch + CPAM — starch first as primary retention plus dry strength, CPAM as fines retention booster. Works on neutral/alkaline fine paper.
• CPAM + bentonite (microparticle) — CPAM dosed at headbox, bentonite at fan pump. Forms shear-resistant flocs ideal for high-speed machines (1,200+ m/min).
• CPAM + colloidal silica — similar to bentonite but with finer flocs and better formation. More expensive but worth it on premium grades.

We supply the CPAM half of these systems and frequently work with customers' existing chemical suppliers to coordinate dosing strategy. Send us your current wet-end chemistry list and we will tell you whether we see an obvious optimization opportunity.

Our Paper Grade PAM

At our Zhengzhou factory, we produce CPAM specifically formulated for paper making applications:

• Retention/drainage grades: 8-15M MW, 20-60% charge density
• Dry strength grades: 1-3M MW, 10-30% charge density
• White water treatment grades: 8-12M MW, 40-70% charge density

All grades follow our published powder-grade baseline of ≥90% solid content, with dissolution time and residual monomer confirmed by grade and batch. TDS, COA, and SDS can be provided for buyer review before bulk ordering.

We also supply APAM for paper mill effluent treatment — a complementary route for mills that want one supplier discussion covering both wet-end chemistry and wastewater clarification.

Ordering

MOQ: 500kg for first orders. Standard delivery: 7-10 days. We currently supply paper grade PAM to mills in Indonesia, Vietnam, India, Brazil, and Egypt. For more details on our paper-specific retention aid products, see PAM retention aid guide. Also check our dissolving method guide for optimal preparation.

Contact us on WhatsApp at +86 187-3759-0940 or request a quote. Send us your furnish composition and machine type, and we will recommend the right grade.

Frequently Asked Questions

What type of PAM is used in paper making?

Cationic polyacrylamide (CPAM) is the primary type used in paper making. Specifically, CPAM with 20-60% charge density and 8-15M molecular weight is used for retention and drainage, while low-MW CPAM (1-3M Da) at 10-30% charge density serves as a dry strength agent. The cationic charge neutralizes the naturally anionic cellulose fibers and fillers.

How much PAM do you add per ton of paper?

Typical dosage ranges from 0.3-2.0 kg/ton paper for retention/drainage applications, and 5-15 kg/ton paper for dry strength. The exact dosage depends on furnish composition, filler content, machine speed, and water quality. We provide free jar testing to determine optimal dosage for your specific conditions.

Can PAM replace starch as a dry strength agent?

PAM can partially replace starch in dry strength applications. While starch remains the most common dry strength agent (typical dosage 10-30 kg/ton), adding 5-10 kg/ton of low-MW CPAM can reduce starch consumption by 30-50% while maintaining equivalent strength. This is particularly cost-effective when starch prices are high.

Get a Quote

Our factory in Zhengzhou produces confirmed grade availability across core APAM, CPAM, NPAM, and PHPA products. MOQ 500kg, delivery 7-10 days standard. Contact us for pricing and free sample:

• WhatsApp: +86 187-3759-0940
• Email: info@chinapolyacrylamide.com

For a complementary view, see our paper making retention & drainage aid.