# Theoretical and Experimental Analysis for Cleaning Ice Cores from EtisolTM 140 Drill Liquid
## 3 Experimental Testing  
### Ice Core Cleaning  
The theoretical values discussed in Section 2 are at odds with practical experience handling ice cores at drilling sites. It is a common observation, that over the course of a few days, fresh ice cores do in fact loose fluid. We, therefore, decided to perform a few tests. The tests were done using real 10 cm full ice cores, 55 cm long (Figure 3), taken from a depth of 400 m at the NEEM \"North Greenland Eemian Ice Drilling\" deep drilling site in Greenland. The ice cores were initially weighed as dry cores. The average weights were about 3800 g, in agreement with the ice density, accounting for some bubbles and porosities. The scale used for weighing, had an uncertainty 0.3 %, which for a full core means \(\pm\)1.1 g. The cores were then soaked in Estisol\({}^{\text{TM}}\) 140 and wiped with paper towels to mimic the fluid removal during drilling by the drillers with vacuum-cleaning and wiping down. Then the cores were weighed again to measure the initial amount of drilling liquid. The weighing was repeated after 8.5, 39.5, 46.0, 95.0, 121.0, and 145.5 h. We assumed that the difference in weight represented the residual amount of drilling liquid. Between the measurements, some cores were kept in a ventilation chamber, some in a closed box and some were positioned in a core trough and some were resting on open supports. Additionally, tests  
Figure 2: Maximum ice sublimation and Estisol\({}^{\text{TM}}\) 140 evaporation after one week ventilation at 40 m\({}^{3}\)/h as a function of the temperature and relative humidity of the inlet air. If, as assumed, the air is collected from a hole in the ice the relative humidity is 100% and the ice loss goes to zero. were done at different temperatures: \(-18\)\({}^{\circ}\)C, \(-30\)\({}^{\circ}\)C, \(-50\)\({}^{\circ}\)C. A sketch of the experimental configurations is shown in Figure 3.  
Figure 4 shows the residual amount of Estisol(tm) 140 as a function of time for the different drying conditions. The reason for the high initial value of 14 g residual fluid of the \(-50\)\({}^{\circ}\)C test is that the fluid at this temperature has significantly higher viscosity and, therefore, the ice core is able to retain more fluid at the initial soaking. We note, that after 46 h all the curves reach a plateau, and from then on the variations fall well within the uncertainty on the single measurements, which we estimate to about 1 g, which is shown as error bars in the figure. For the samples kept at \(-18\)\({}^{\circ}\)C and \(-30\)\({}^{\circ}\)C, we compared a sample stored in a ventilated chamber resting in a trough with a sample stored in a closed box and resting on open supports. In contrast with the previous theoretical discussion, we find that the rate of fluid loss and the final amount of residual fluid does not show a strong temperature dependence. We also see that the influence of ventilation is less than the influence from the choice of core trough or not in removing the residual amount of fluid. The fluid loss is much faster when the ice cores are on open supports, as shown by the much higher lapse rate for open supports in both the \(-18\)\({}^{\circ}\)C and the \(-30\)\({}^{\circ}\)C experiments. As we examined the samples in the core troughs, we noticed that fluid had collected in the bottom of the troughs. We took that as an indication of fluid loss by run-off and dripping, which is highly probable as the fluid has low viscosity and has low surface tension, cf. bio-diesel or low viscosity vegetable oils. We also think we can explain the different plateaus for troughs and open supports. Along each side, the core rests against the trough. The lines of contact act as gutters for the fluid running off the top of the core, and we observed two stripes of excess fluid along the lines of contact as we removed the cores. Therefore, in agreement with theoretical calculations, we can infer that evaporation of the drilling liquid is not a first order effect. Gravity driven run-off is the most significant process in fluid loss.