During actual viscometry, the agZIF-62 substrates were placed on a polished alumina plate and the sapphire ball (R = 0.75 mm) was positioned on top, being loosely held in place by a support ring to prevent extensive lateral movement of the sphere on the flat sample surface. Samples were heated to different temperatures T > Tg at a rate of 2 K/min, and subjected to isothermal treatment for varying times at these target temperatures. During these treatments, a normal load was applied on the sapphire ball at the beginning of the isothermal segment. The recorded normal displacement of the sapphire ball h over time t was zero-point corrected for any offsets based on accumulated expansion during the heating cycle and the displacement jumps upon application of the desired mechanical load (caused by instrument frame compliance). The such-corrected penetration data were fitted using the relation of Douglas et al. :