Testing the Processing-Induced Roughness of Sanded Wood Surfaces Separated from Wood Anatomical Structure

Round 1

Reviewer 1 Report

The manuscript is interesting and well-prepared. Nevertheless, there are some small issues that need to be addressed before publication. Here are some of my comments and recommendations towards the improvement of this work. 

In the title, the "Processing Roughness" probably needs to be changed into "Processing induced roughness" in order to be more comprehensive (at least in the title). In line 15, you rather use included instead of taken. In line 47, please provide the unit of 1.25 cut-off length. In line 49, you rather mention except for the cavities, also the differences in density of wood that cause such phenomena (for example earlywood-latewood transition, tensile wood-normal wood etc.). The author is recommended to find relevant information concerning this topic and probably incorporate them in the theoretical approach (introduction) among others on https://doi.org/10.3390/app10186265. There is a lack of commas detected in the whole text of the manuscript (please, make a check to syntactical/grammatical errors), since it deteriorates the readability (some meanings are not so clear due to that, for example in lines 53-54 a word is missing?). In line 54, probably you mean "a result of" and not "a cause of" as you refer?  Since the roughness field is already complicated, we rather try to be accurate with words. In line 84, you rather say efficacy on the surface roughness of different species and after sanding of different grit numbers... etc. (efficacy on what? probably on the seperation?please rephrase to be clear). In line 124-125, if there is any reference please provide it. In line 134, it would be helpful to add a characterization of the species in parentheses (ring-porous, coniferous etc.). In materials-methods section, please insert a brief comment related to the moisture content of the different species wood specimens concerning the time of roughness measurement. 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This research is very significant. The biological roughness of wood can greatly affect the sanding surface roughness. So far there is no effective method to evaluate the true sanding roughness of wood. I hope the author can further refine your research. It is very important to predict wood surface roughness and control wood processing parameters. However, some details need to be improved and clearer.

1. How the thresholds were determined for the assessment of wood surface roughness parameters? If surface roughness of plastic is used to determine, then please consider the difference of elastic deformation between plastic and wood, as well as the densification phenomenon of wood surface and subsurface during sanding process. Given this, the actual threshold might be a little bit lower.
2. Line 162-163, you mentioned “50 mm long for wood specimens and 20 mm for plastic”, while the profile depicted in Figure 11 was not complete and the description in line 168 was contradictory.
3. Line 184-185, please specify the selected evaluation length in this paper.
4. Line 202 to 207, the main reason may be caused by the difference of material characteristics between wood and plastic, like plastic has no pores inside and show greater ductility. So, it’s better to mention the different surface creation mechanism in sanding to partly account for the Rt variation.
5. Maybe the author can try another way to determine the threshold. Gradually increasing the grit size and finding a relatively stable roughness, and the threshold would be obtained at this critical condition. That means the roughness of sanding trace reach the roughness of wood anatomical structure, namely sanding can’t remove the roughness of wood anatomical structure. And I think the P1000 has already reached the roughness of most wood anatomical structure. Don't need to modify it, for reference only.
6. Some discrete roughness values may result from the fiber warping created in sanding process. Micrographs of sanded surface for wood and plastic, like SEM images, could be helpful to distinguish some fiber raisings or processing defects.

Author Response

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Author Response File: Author Response.docx