Size Distribution: The size distribution of glass bubbles is characterized using techniques such as laser diffraction or microscopy.

Wall Thickness: The wall thickness of the glass bubbles is measured using scanning electron microscopy (SEM) or transmission electron microscopy (TEM).

Density: The density of glass bubbles is determined using methods such as gas pycnometry or helium pycnometry.
Compressive Strength: The compressive strength of glass bubbles is measured using a universal testing machine.

Thermal Properties: The thermal conductivity and expansion coefficient of glass bubbles are determined using thermal analysis techniques such as differential scanning calorimetry (DSC) and thermal conductivity measurements.

Chemical Composition: The chemical composition of glass bubbles is analyzed using techniques such as X-ray fluorescence (XRF) or inductively coupled plasma (ICP) spectroscopy.

Characterization of glass bubbles is essential to ensure their suitability for specific applications, such as lightweight fillers, syntactic foams, or insulation materials.