Paint thickeners play a vital role in the performance and feel of water-based paints. They help control viscosity, improve texture, and ensure smooth application whether you're using a brush, roller, or spray. Understanding the types of thickeners available and how they work is essential for paint manufacturers, contractors, and DIY users aiming for high-quality, consistent results.
In this guide, we explore the main types of paint thickeners used in water-based paints, their characteristics, and specific use cases in both decorative and industrial coatings.
Paint thickeners also known as rheology modifiers are additives used to adjust the viscosity (thickness) of paint. In water-based systems, thickeners help stabilise the formulation, reduce dripping or sagging during application, and improve the overall flow and levelling of the paint.
These additives ensure that pigment and binder components remain evenly suspended, preventing settling and separation in the can or on the surface.
Water-based paints are widely used in South Africa and globally due to their low odour, fast drying time, and eco-friendly formulation. However, because water has low viscosity on its own, paint formulations need thickeners to:
Maintain consistency during manufacturing and storage
Prevent splatter and dripping during application
Ensure smooth, even coverage
Stabilise pigment dispersion for uniform colour
Description:
One of the most common thickeners in water-based paints, HEC is a water-soluble polymer derived from cellulose. It provides efficient thickening and excellent colour retention.
Key Features:
Cost-effective
Excellent water retention
Good stability in storage
Applications:
Interior wall paints
Primers and sealers
DIY and retail-grade paints
Description:
Associative thickeners form networks by interacting with other ingredients in the paint. These include:
HEUR: Hydrophobically modified ethylene oxide urethane
HASE: Hydrophobically modified alkali-swellable emulsions
ASE: Alkali-swellable emulsions
Key Features:
Tailored rheology (flow) control
Improved levelling and film build
Enhanced scrub resistance
Applications:
High-performance decorative coatings
Low-VOC and environmentally friendly paints
Spray-applied formulations
Description:
These synthetic polymers offer excellent flow control and compatibility with a wide range of water-based binders.
Key Features:
High shear stability
Minimal impact on gloss
Good for tintable bases
Applications:
Industrial coatings
High-gloss finishes
Paints requiring tinting accuracy
Description:
Naturally occurring or modified clays used to provide thixotropic (shear-thinning) properties, helping paints to stay thick in the can but flow easily when applied.
Key Features:
Excellent anti-settling behaviour
Stabilises pigments in complex formulations
Ideal for textured coatings
Applications:
Textured and decorative plasters
Masonry paints
Anti-corrosive primers
The ideal thickener depends on:
Desired viscosity and application method (e.g., brush vs. spray)
Formulation requirements (e.g., VOC compliance, gloss level)
Environmental factors (e.g., humidity, temperature)
For example:
HEC is great for DIY and entry-level products.
HEUR suits professional-grade, low-VOC paints.
Clay thickeners work best in heavy-bodied or textured coatings.
Improved application performance
Better storage stability
Drip- and sag-resistance on vertical surfaces
Reduced pigment settling and syneresis
Enhanced user experience for both pros and homeowners
