Aluminium trihydrate (ATH) for solid surface manufacturing
Aluminium trihydrate (ATH) is the most widely used mineral filler in the solid surface industry. Unlike other conventional mineral fillers such as calcium carbonates or dolomite, aluminium trihydrate has a refractive index virtually identical to that of ISO-NPG resin. This optical matching provides solid surface with its signature translucent natural stone appearance, enabling pure white tones and a depth of color unattainable with other mineral fillers. At AITANACHEM we supply high-grade ATH filler specifically selected for premium solid surface casting. High-purity ATH mineral filler featuring superior whiteness, controlled particle size distribution, and optical refractive matching for pure, durable, and renewable solid surface production.
What is Aluminium Trihydrate (ATH)?
“ATH” stands for aluminium tri-hydrate (aluminium trihydrate). Chemically classified as aluminium hydroxide, Al(OH)₃ —also expressed as Al₂O₃·3H₂O—, it consists of alumina bound with three water molecules. It presents as a fine white powder of high purity that provides exceptional whiteness and great optical translucency. These physical properties are highly valued and make ATH the ideal mineral filler for accurately reproducing rich color palettes in solid surface formulations.
Key Advantages of ATH Filler in Solid Surface Manufacturing
Compared to alternative mineral fillers, aluminum trihydrate offers distinct operational advantages during casting and in the finished solid surface product:
- High Chemical Resistance: Excellent tolerance to household chemicals and mild acidic agents.
- Easy Repairability and Sanding: Allows finished cast parts to be fully repaired and restored to their original surface finish. ATH provides optimal hardness, ensuring the final composite is solid, non-porous, and 100% renewable.
- Whiteness and Optical Translucency: Facilitates clean, vibrant, and faithful color matching.
- Synergy with Secondary Fillers: Blends effectively with other fillers; for instance, combining ATH with Boehmite enhances scratch resistance, surface gloss, and stain resistance in the final product.
How to Select the Right ATH Filler for Your Production Line
The mineral filler has a direct impact on the process: it governs viscosity, affects catalysis kinetics, can cause shrinkage, and modifies final aesthetic appearance and final colour. Key technical criteria to choose the most suitable ATH include:
- Particle Size Distribution (Granulometry): Very coarse particles tend to sink to the bottom of the mould, whereas excessively fine particles increase resin demand and hinder dispersion. An optimized particle-size distribution ensures optimal dispersion of the mass, reducing casting viscosity and facilitating smooth mould injection.
- Particle Morphology (grinding) and Wetting: Particle shape influences resin absorption. Engineered grain selection and surface treatment facilitate rapid particle wetting by the resin, preventing agglomerate formation and shortening cycle mixing times.
- High Whiteness and Purity (No Black Spots): Metal contaminants (Fe, Ni, Cu) in the ATH cause unsightly black spots or dark specks in finished parts. At AITANACHEM, we supply ATH with a whiteness index exceeding 96, providing a clean base for uniform color when blended with concentrated pigment pastes.
- Silanization Treatment: Surface treatment with silane coupling agents improves filler dispersion and matrix translucency, boosts thermal shock and water vapor resistance, lowers thermal expansion, and shortens gel and curing times.
AITANACHEM: On-Site Formulation Optimization and Mineral Filler Adjustment
At AITANACHEM, we assist engineering teams in selecting the most suitable mineral filler based on your equipment and product portfolio:
- Viscosity Testing: we determine the maximum amount of mineral filler your resin can take without compromising the fluidity of the mix or generating air bubbles or micro-porosity.
- Local Filler Compatibility: we assess the possibility of combining a high-whiteness ATH with local mineral fillers to reduce overall raw material supply and freight costs.
- Vacuum Degassing Guidance: we guide you in adjusting degassing times to ensure cast parts that are 100% porosity-free.
Frequently asked questions about Aluminium Trihydrate (ATH)
What does ATH stand for, and what is its chemical formula?
“ATH” stands for aluminium tri-hydrate. Chemically known as aluminum hydroxide – Al(OH)₃, ATH is a fine white mineral powder used as the primary filler in solid surface manufacturing due to its whiteness, translucency, and sandability.
Why is ATH preferred over calcium carbonate or dolomite in solid surface casting?
Calcium carbonate and dolomite are opaque minerals; they do not allow the renewable polishing characteristic of solid surface and are sensitive to attack by household acids. ATH has a refractive index close to polyester resin, providing depth of color, chemical resistance, and the ability to repair scratches by sanding.
How does particle size (granulometry) affect the manufacturing process?
An excessively fine particle size dramatically increases resin’s viscosity, making impossible to add a high percentage of mineral filler to the mix. Conversely, coarse grains decant to the bottom of the mould before the gel point is reached. At AITANACHEM we supply balanced granulometries that optimise viscosity and prevent particle settling.
What causes black spots in cast solid surface parts?
Black spots are typically caused by metallic impurities in raw mineral fillers. A simple quality test involves passing a high-power magnet over the dry ATH powder before and after processing through machinery to check for magnetic particles.
Does ATH expire or require special storage conditions?
ATH is a chemically stable mineral that does not expire. However, it must be stored in a dry, it must be stored in a dry, sealed environment to prevent moisture absorption, as free water in the filler negatively impacts resin catalysis.
ATH as a Flame Retardant (other applications)
Beyond its aesthetic and structural role in solid surface casting, aluminium trihydrate is globally recognised as an eco-friendly flame retardant and smoke suppressant in the broader plastics and composites industry.
When exposed to elevated temperatures (starting at approximately 200 °C), ATH undergoes an endothermic decomposition reaction, releasing approximately 34.5% of its weight as water vapor. This endothermic process absorbs heat from the fire source, cools the polymer matrix, dilutes flammable gases, and quenches flames without emitting toxic or corrosive fumes. This makes ATH an indispensable additive in industries governed by strict fire safety regulations. If you are interested in exploring other mineral fillers and their applications, visit our page on mineral fillers for composites
Do You Need the Right ATH Filler for Your Production Line?
Whether you want to optimize part whiteness, lower viscosity, or request laboratory samples of aluminum trihydrate for trials, our technical engineering team is at your disposal. Contact us today and we will recommend the ATH mineral filler grade best suited to your production requirements.
To better understand how to integrate ATH filler within a complete manufacturing project, review our master guide on solid surface raw materials and technical support.