Cause of delayed onset of heterogeneity at low salt in Laponite suspensions

Determine whether the delayed onset of structural heterogeneity observed at low salt concentrations in 1 wt% Laponite suspensions is caused by structural disruption due to pipetting prior to observation or by slow redistribution of salt ions during quiescent storage, and quantify the relative contributions of these mechanisms.

Background

In the low-salt regime (0–2 mM NaCl), the authors observed that Laponite suspensions remained homogeneous for extended periods before developing heterogeneity. They suggest two potential explanations for this delayed onset: structural disruption introduced by pipetting during sample handling, and slow redistribution of salt ions during storage.

The explicit uncertainty concerns which mechanism (or combination thereof) is responsible for the delayed heterogeneity. Resolving this question is important for standardizing sample preparation and interpreting aging behaviors in low-concentration, low-salt Laponite systems.