Cellulosic fibre charge and hydrogen bonding

Paper fibres carry electrical charges that affect how they behave in water.

The fibres, due to their cellulose nature, attract one another through positive and negative charges on hydroxyl groups. These interact with water molecules via hydrogen bonding. This hydrogen bonding is crucial to forming the sheet of paper after it has been couched and is essential to the sheet’s strength and integrity.

Fibre clumping in the vat

However, in the vat, this chemical reaction causes the cellulosic fibres to attract one another and clump. Without any additives, pulp can behave unpredictably in the vat. The fibres naturally cling together in small clumps, leaving other areas of the water relatively clear. When you pull a sheet from this uneven suspension, the result is often patchy: some areas become dense and heavy with fibres, while others remain thin, weak, or even bare on the mould.

Role of a deflocculant for fibre dispersion

To form an even sheet of paper, with the pulp taken up evenly and the fibre spread across the mesh of the mould, one must adjust the electrical charge in the vat. The aim is to keep the fibres dispersed rather than clumped. To do so, a deflocculant is mixed well with the pulp in the vat.  A deflocculant gives the fibres a negative charge, so they repel each other. This rejection causes dispersion, with the fibres moving freely through the water rather than clumping, allowing the formation of an even sheet.

Maintaining fibre suspension in the vat

In addition, the deflocculant has a mucilaginous, almost gel-like quality that helps keep the fibres suspended throughout the vat, rather than sinking to the bottom, allowing the papermaker to form thin sheets. This suspension is particularly important when you want to make very thin or delicate sheets. Because the fibres remain evenly distributed, each sheet you pull can be more consistent in thickness and character. In this way, the deflocculant supports both the technical precision of the papermaker and the aesthetic qualities of the finished paper.

Using a deflocculant with Typha capensis

When making paper from locally sourced fibres such as Typha capensis, a deflocculant plays an equally vital role alongside cellulosic fines. Because Typha capensis tends to form woolly clumps in the vat, carefully adjusting the fibre charge ensures they remain evenly dispersed throughout the water. By introducing a deflocculant, we encourage Typha capensis fibres to repel one another and remain in suspension, enabling the formation of consistently thin, well-structured sheets. This control over dispersion not only stabilises the papermaking process when working with Typha capensis but also brings out the texture and character of this plant fibre in the finished paper.