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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Endpoint summary

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Administrative data

Description of key information

The information on the physical and chemical properties were from test results with test sample provided by Lead Registrant Kemira or either cited from peer-reviewed database or handbooks. These studies followed standard guidelines for methodology and so the data is considered reliable and suitable for use. Expert judgement-based waiving are applied for the endpoints on which tests are not necessary.

The reference substance (anhydrous form) is a dense, crystalline solid at ambient temperature, with negligible volatility. In water, it is very soluble, without surface-active properties, and complex pH-dependent speciation.

It decomposes upon heating, and is not classified for physical hazards, based on CLP criteria, but solutions may be corrosive to metals.

Additional information

Summary of relevant physico-chemical properties:


Aluminium sulphate anhydrous

 18 H2O


Solid (white odourless crystals)

 Solid (colourless crystals)

Melting point

decomposes at 770°C

 primary decomposition corresponding to crystal water loss from ca 80°C

Relative density



Water solubility

Aluminium sulphate is considered as a very soluble salt (>> 100 g/L), however aluminium speciation rapidly leads to salting out to various degrees which are water quality-, and expecially highly pH-dependent. Solubility of monomeric Al can descend as low as 12 µg Al/L.

Surface tension

 73 mN/m at 1 g/L (analogue)


Not expected to be flammable (used as fireproofing agent).

No flammable properties expected if contact with air or water.

Not flammable (no propagation if contact with a flame) (from analogue).

No self-heating anticipated (from analogue).

No flammable properties expected if contact with air or water.

Explosive properties

No explosive properties anticipated (based on chemical structure).   

Oxidising properties

No oxidising properties anticipated (based on chemical structure and use as fireproofing agent).   

 Dissociation constant Not required (forms various hydroxides and polymeric species, depending on pH).
 Granulometry Process-dependent.