Your guide to fluidisers in gypsum board production

Fluidisers, also called dispersants or plasticisers, help gypsum particles spread evenly in the slurry. In practical terms, they are used to:

• improve slurry flow and handling

• reduce the amount of water needed

• support stable and predictable setting

• maintain smooth production at high line speeds

Because fluidisers influence several process parameters at the same time, their performance depends on the type and quality of the gypsum used. Changes in gypsum source (natural, synthetic or recycled gypsum), fineness or impurity levels can increase variation in the process.

As a result, fluidiser choice becomes more important when raw-material variability increases. In these situations, producers often look for robust fluidisers that maintain stable performance across different gypsum qualities and production conditions.

PNS fluidisers have been widely used in gypsum board production for many years because they provide strong dispersion and stable performance. However, several developments are leading producers to reconsider their use:

• tighter regulation related to formaldehyde, especially in Europe

• increased focus on indoor air quality and safer building materials

• sustainability targets that aim to reduce fossil based raw materials

• expectations that European regulation will influence global requirements

In Europe, formaldehyde and formaldehyde releasing substances are regulated under the EU chemicals legislation REACH, with information and guidance published by the European Chemicals Agency (ECHA).

 → External reference: European Chemicals Agency – Formaldehyde restrictions under REACH

 In July 2023, the European Commission adopted Commission Regulation (EU) 2023/1464, which adds formaldehyde and formaldehyde‑releasing substances to Annex XVII of the REACH Regulation and introduces new emission limits that apply from August 2026.

 → External reference: Commission Regulation (EU) 2023/1464 (EUR‑Lex) 

As a result, many gypsum board producers are no longer only comparing fluidiser performance. Instead, they are focusing on how to replace PNS while maintaining stable production and consistent board quality.

Several fluidiser types are used in the gypsum board industry today. Each has different strengths and limitations.

PNS fluidisers

• synthetic products based on fossil raw materials
• strong dispersing effect
• generally stable across different gypsum qualities
• increasing regulatory and sustainability concerns
  
  

Polycarboxylate ethers (PCE)

• very strong water‑reduction effect
• often sensitive to gypsum quality and other additives
• mainly used in selected or specialised applications
  
  

Lignin‑based fluidisers (Lignosulfonates)

• produced from renewable, wood‑based raw materials
• long history of use in construction and mineral applications
• available in different grades with different performance levels
• robust towards changes in gypsum board raw materials
  

Read more >  Borregaard is the world's leading producer of lignosulfonates

Lignosulfonates work by attaching to gypsum particles and helping them stay separated. This improves flow and reduces water demand. Their performance depends on factors such as molecular structure, purity and the way they are produced.

It is important to understand that lignosulfonates are not all the same. In gypsum board applications, it is common to distinguish between standard‑grade and superior‑grade lignosulfonates:

Borregaard is a supplier of lignin‑based fluidisers and offers both standard‑ and superior‑grade lignosulfonates. The choice between these grades depends on process requirements, gypsum variability and how much process variation a plant can accept.

When lignin‑based fluidisers are evaluated as alternatives to PNS, producers usually look at:

• slurry flow and water reduction

• setting behaviour and consistency

• performance with different gypsum qualities

• interaction with other additives

Laboratory work and industrial trials show that modern lignin‑based fluidisers can achieve performance similar to PNS, when the formulation and dosage are adjusted correctly.

Rather than aiming for a simple direct replacement, successful projects focus on understanding how the fluidiser works in the full formulation and how it behaves with the specific gypsum sources used.

Learn more: Ultrazine caF performance in gypsum board production - compared with PNS

In addition to performance and regulatory requirements, many gypsum board producers are evaluating the carbon footprint of the additives used in their formulations. Demand for lower-carbon building materials is growing, and sustainability initiatives such as Environmental Product Declarations (EPDs), the Energy Performance of Buildings Directive (EPBD), the revised Construction Products Regulation (CPR) (EU) 2024/3110, and future Digital Product Passport (DPP) requirements are increasing the focus on the environmental performance and carbon footprint of construction products. As a result, manufacturers are taking a closer look at how raw materials and additives contribute to the overall carbon footprint of gypsum boards.

Lignin-based fluidisers are produced from bio-based raw materials and can offer a lower carbon footprint than fossil-based alternatives such as PNS. EPDs provide a transparent way to compare these impacts and support more sustainable product choices.

Read more: See how you can reduce the carbon footprint of your gypsum boards by switching from PNS to Ultrazine CAF 

Replacing a current fluidiser is rarely a simple switch. A step‑by‑step approach helps reduce risk and supports stable production. In practice, this often includes:

• testing with relevant gypsum types (natural, synthetic and recycled)

• evaluating performance under realistic process conditions

• adjusting dosage based on overall formulation behaviour

Producers that treat PNS replacement as a planned transition, rather than a quick change, are better able to maintain consistent board quality and stable production.

Are lignin‑based fluidisers suitable for both natural and synthetic gypsum?
Yes, but performance depends on grade selection and formulation design. More variable gypsum often requires more stable fluidiser grades.

How does recycled gypsum affect fluidiser performance?
Recycled gypsum can increase variation in the process. This places higher demands on fluidiser performance and evaluation.

Is it possible to fully replace PNS in gypsum board production?
Industrial experience shows that replacement is possible when the transition is properly planned and supported by testing.

For producers preparing to move away from PNS, the next step is usually to review current formulations, select suitable lignin‑based fluidiser grades and plan laboratory and plant‑scale trials.

Borregaard supports customers in this process by supplying lignin‑based fluidisers and providing technical support during evaluation and implementation.

Need support evaluating your formulation or production process?

Selecting the right fluidiser for gypsum board production often requires balancing performance, gypsum variability, process stability, sustainability goals and regulatory requirements.