Figure 2: Colloid particles being push out of the advancing solidification interface and starts to agglomerate (1).

the bottom of the drum or IBC where the silica has precipitated out of suspension. A binder that exhibits a low pH and reduced silica content should not be used.

Testing a Colloidal Silica Binder That Has Been Subjected to Subzero Temperatures All binder packaging will have a freeze indicator attached to it once it has been produced. The indicator will show if the packaging has been exposed to temperature below 0°C (see the image below). If the indicator shows that the binder has been in subzero conditions consult your REMET representative prior to use. It is also a good practice to place a temperature data logger in the location where the colloidal silica is kept.

However, if the product is in an IBC or drum, even though the freeze indicators are activated, the product may not have been affected by subzero due to the large binder volume. To be certain, the binder viscosity, silica content and pH test can be used to assess the bulk effect on the material.

We also suggest that to make sure there is no aggregation of colloidal silica occur during the freezing condition, a sample can be taken from the IBC and centrifuged. The supernatant from the centrifuge can be used to determine the percentage of free suspended colloidal silica available. A low silica percentage


is an indication that the colloidal sol has been through a sufficiently long freezing condition and the sol is not suitable for use.

The Impact of Temperatures Between 1°C and 5°C on a Colloidal Silica Binder

Binder performance is not impacted by temperature under 5°C providing the material has not frozen (Remember that the freeze indicator only indicates that the material has been exposed to freezing conditions, not that the material is frozen or damaged). The impurities/ ions in colloidal silica reduce the freezing point of a pure water. However, there are a few simple quality control tests that can be carried out to assure if the colloidal silica is good to be used, for example Brookfield binder viscosity test, Potentiometric titrator (surface area of colloidal silica) or simple pH meter and silica content test.

For more information on testing

your colloidal silica material, please contact your REMET representative.


1. In situ cryogenic transmission electron microscopy for characterising the evolution of solidifying water ice in colloidal systems. Tai, K., Liu, Y. and Dillon, S.J. 20, s.l. : Microscopy and Microanalysis, 2014, Vols. pp. 330-337.

Disclaimer on

Information and/or recommendations based

information received are

believed to be reliable. Offered free of charge for use by persons with technical skills, at their own discretion and risk, without guarantee of accuracy REMET makes no warranties, express or implied, and assumes no liability as to the use of its products or of any information pertaining thereto.

November 2019 ❘ 19 Figure 3

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