Recently, we developed a hot-stage microscopy technique for measuring the temperaturedependent viscosity of SOA. This technique involves heating an SOA sample with non-spherical geometries and quantifying the change in shape of the SOA sample due to heating with an optical microscope. From the shape change, viscosities can be calculated. This method worked as expected for farnesene SOA. However, when attempting to measure the temperature-dependent viscosity of SOA generated by the ozonolysis of catechol, surprisingly, the volume of the SOA increased when heated to mild temperatures (36-52 °C).