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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Viscosity

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Description of key information

The viscosity of pure formaldehyde does not need to be determined  because the substance is a gas at 20 °C / 1013 hPa. 
The viscosity of aqueous formaldehyde solutions ranges from 2.083 to 2.835 mPa s at 20°C depending on formaldehyde concentrations (30.19 - 40.08% ) and methanol concentrations (0.95 - 11.95%).

Key value for chemical safety assessment

Additional information

Viscosity pure formaldehyde

The viscosity study does not need to be performed because the substance is a gas at 20 °C / 1013 hPa. The DIPPR Project (2013) does however report a viscosity of pure liquid formaldehyde of 1.56 mPa s at -118 °C and 0.26 mPa at -19.3 °C.

Viscosity of aqueous formaldehyde solutions

Four sources were identified concerning the viscosity of aqueous formaldehyde solutions. According to a study perfomed according to the DIN 51 562 guideline by BASF (1987, Key), the viscosity of aqueous formaldehyde solutions ranges from 2.083 to 2.835 mPa s at 20°C depending on formaldehyde concentrations (30.19 - 40.08% ) and methanol concentrations (0.95 - 11.95%). A solution containing 37.13% formaldehyde and 0.95% methanol had a viscosity of 2.562 mPa s at 20°C. These values were supported by Ullmans dictionary (2012) reporting 2.1 mPa s (37% formaldehyde at 25°C) and Walker (1967) reporting values of 2.45 mPa s (37 % aqueous formaldehyde solution with 6 % methanol at 25°C) and 1.87 mPa s (30% formaldehyde at 25°C). The Kirk-Othmer (2015) report a lower value of 0.1421 mPa s, but the concentration formaldehyde is unknown.