As introduced earlier, cross-link densities on a low-field spectrometer are measured using an MQ pulse sequence. The method has been detailed elsewhere and is therefore described here only very shortly. The experiment yields two signals as a function of pulse sequence duration, τDQ: a double quantum signal (IDQ) and a decaying reference signal (Iref). IDQ results from contributions of coupled spins at shorter times. Iref also contains a contribution from uncoupled spins (defects) that behave isotropically. A sum MQ signal (IΣMQ = Iref + IDQ) is a fully dipolar refocussed signal that decays due to molecular motions. In networks, this decay is found to be nearly equal to that of an IDQ signal. This enables the removal of the effects of molecular motions from IDQ through normalization by a point-by-point division, satisfying the condition: InDQ = IDQ/(IΣMQ -defects).