A containerboard and high-strength corrugated mill in South Asia came to us with a cost problem dressed up as a quality problem. They wanted to run more local recycled fiber to bring furnish cost down, but every time they pushed the ratio up, ring crush and burst fell away and the sheet got downgraded. Below is the key technical consultation.
Getting More Out of Recycled Fiber
Q: We want to run more recycled fiber to cut costs, but ring crush and burst drop off and the sheet gets downgraded. Is there a way around that?
A: This is exactly where a dry strength agent earns its keep. FU-01 strengthens the bonding between fibers, so it buys back the strength you lose when you push secondary fiber higher - which lets you raise the share of low-cost and recycled fiber while still hitting the same grade spec. The headline saving is furnish cost, but the drainage improvement matters too, because less fiber washing out means lower pulp consumption for the same tonnage.
What Strength Are We Talking About
Q: Which strength properties actually improve?
A: Breaking length, ring crush, burst and folding strength - the dry physical indexes your customers test against. The mechanism is plain: stronger bonding between fibers, so the sheet holds together better under load. You also get better retention of fine fibers and filler, which is where the fiber-loss saving comes from. It is worth setting expectations here - this is about lifting dry strength indexes, not about making a weak furnish behave like virgin kraft.
Will It Fight Our Existing Chemistry
Q: We already run a sizing and retention program. Will adding this interfere?
A: FU-01 is amphoteric and tolerates a wide pH range, so it sits comfortably alongside conventional papermaking chemistry. Added at the right point it does not disturb sizing or retention systems. That is why it fits everything from containerboard, yarn tube base paper and cardboard through to specialty and cultural grades. It performs best on the acidic side, around pH 5–7.
How to Run It
Q: How do we add it, and how much?
A: Dilute it 10 to 20 times, stir evenly, and add to the pulp mixing tank; or feed it continuously online with a metering pump if you want tighter control. Screen the product through an 80–100 mesh filter before use - that step is what keeps potential sheet defects off your paper. Dosage is set against pulp and we tune it to your furnish and grade target. It is widely used on containerboard, high-strength corrugated, yarn tube base paper and tissue.
