We determine the arrival time of a contaminating particle as the time when the standard deviation of the maximum pixel intensity exceeds a predetermined level. Figure 4 (left) is a bar chart detailing the arrival time for every measurement. Figure 4 (right) is a histogram of these arrival times, showing an improvement in the length of time the trap stayed clear of other particles when the shield is used. The mean arrival times with and without a shield are 23 seconds and 3.8 seconds respectively. The effect of a contaminating particle typically increases the viscosity measurement by ∼ 25% and standard deviation by ∼ 90%.