Huber's Alumina Trihydrate (ATH)

Huber supplies a halogen-free Alumina Trihydrate (ATH) grade that will fit almost any flame retardant or smoke suppression application or need in the marketplace. Our scientists have developed and formulated a wide variety of alumina trihydrate grades:

Particle sizes ranging from 0.25 to 80 microns

Untreated and surface treated grades

Ground ATH

Precipitated ATH (high purity; low electrical conductivity)


How ATH Works as a Fire Retardant

Thermal Decomposition Reaction (Endothermic):

2Al(OH)3 + HEAT → Al2O3 + 3H2O Starting @220ºC Consuming 280 cal/g

Alumina Trihydrate (ATH) Properties

Physical Form Powder
Particle Morphology Hexagonal Platelet
Color White
Specific Gravity g/cm3 2.42
pH Value 9 - 10
Hardness, Mohs 2.5 – 3.5
Refractive Index 1.57
Temperature of Decomposition 220°C / 428°F
Heat of Decomposition, cal/g 280
Theoretical loss on ignition, % 34.6


Ground Aluminum Hydroxide

Cost-effective fire retardant

Wide range of particle sizes (1-50 microns)

Irregular particle morphology, wide particle size distribution

Higher surface area

Available with surface treatments
(including vinyl, alkyl, phenyl)

Precipitated Aluminum Hydroxide

Regular crystal shape, narrower particle size distribution

Lower surface area, higher chemical purity

Select grades available with silane surface treatments
(including vinyl, alkyl, phenyl)


Halogen-Free Flame Retardant
& Smoke Suppressant Applications