The authors have responded well to both referees comments, and have made extensive revisions to their manuscript. I have identified only a couple of places where I think the manuscript needs attention. These should be easy to resolve before final publication.

1. There needs to be an explanation in the text for the identical density and porosity between experiment 1 and experiment 2. Even if the two specimens come from the same bulk sample, it would be surprising if they had the exact same density-- was the density measured on the bulk sample but not on the experimental specimens? In any case, if the density can only be determined to 5%, far too many significant precisions are included in table 1.

2. The wording of the revision in response to R1's comment 18 is a bit confusing: I would recommend writing: "The mean pore size distribution(d_mean) was estimated using the opening-size-distribution operation. This operation can be imagined..."

3. The revision in response to R1's comment 23 is not clear. I think there are some words missing from the second sentence, and the authors need to be clear whether the memory effect is known to have been important, or whether it is one possible effect that might have produced the observer result.

4. At lin 196 of the annotated manuscript, there's a sentence that begins "In wind pumping theory..." I'd recommend rewriting this sentence in the active voice to make clear who used the wind-pumping theory, and then make clear whether your calculation of Re also uses the same wind-pumping theory.

Thanks for the revisions, and congratulations on a good manuscript.

During proof editing please look at your revision:
“In the first approximately 30 min, the isotopic composition of the measured outflow air δ18Oa increased from a low δ18O to a starting value of around -29‰ in each experiment. This was due to memory effect and one possible effect might be condensed water left in the tubes from a prior experiment which had no further impact on the experiments (Penna et al., 2012)."
The second word "effect" should probably be "cause."

Best
Ben