Flammability Characteristics of Animal Fibers: Single Breed Wools, Alpaca/Wool, and Llama/Wool Blends
Round 1
Reviewer 1 Report
This is an interesting study evaluating the fire behavior of different animal fibers as function of breed. The topic is appropriate to the journal and more specifically to the special issue. Unfortunately, the paper needs some revisions in the current state.- the structure of the fabrics (diameter, morphology and so on) should be investigated- why samples were not conditioned prior to testing ? this could change the behavior during the test-why only three samples for vertical flame test ? would it be possible to repeat the test for samples that showed completely different behavior (e.g. Llama/Merino Blend ) ?- Table 1: average values should be reported as well- would it be possible to analyze the structure of the charred residue (for instance after PCFC) using IR or raman ?- table 2, from this table some values are different (check for instance the grey Llama merino pkHRR and THR values)-what is the standard deviation for values in table 4 ? is a difference of 0.8-04 in S significant ?-the densities of the fabrics are different, this could play a significant role, why the authors have selected samples with different densities ? is this a matter of availability ? have the authors selected the products that are more likely to be employed in the industry ?-tables should be converted into a proper format- the number of figures should be reducedAuthor Response
Thank you for taking the time to review this paper. The responses to each of the comments are given below in red color text.
This is an interesting study evaluating the fire behavior of different animal fibers as function of breed. The topic is appropriate to the journal and more specifically to the special issue. Unfortunately, the paper needs some revisions in the current state.- the structure of the fabrics (diameter, morphology and so on) should be investigated-
I am not sure what is being asked for here. Is the reviewer asking for diameter of the yarns used? Characterization of the yarn density is given in Table 5, as is the density of fabrics that were knit. Pictures of the fabrics which would give the morphology are given in Figures 18, 19, and 20 in the revised manuscript. Therefore, I believe we have investigated them given the resources we have at our disposal.
why samples were not conditioned prior to testing ? this could change the behavior during the test-why only three samples for vertical flame test ? would it be possible to repeat the test for samples that showed completely different behavior (e.g. Llama/Merino Blend ) ?-
The reviewer is correct that pre-conditioning of the samples in humid atmospheres would have improved the fire performance of the fabrics, but more realistic results are obtained via ASTM D6413 testing if no conditioning is done prior to testing. However, we did allow the samples to equilibrate to lab conditions prior to testing by simply allowing them to remain exposed to lab atmosphere (typically 70 °F, 30-40% relative humidity) for 24 hours. This would be uncontrolled conditioning, but is worth mentioning in the paper, and I have added that information to the experimental section.
Table 1: average values should be reported as well-
Averages have been included in Table 1.
would it be possible to analyze the structure of the charred residue (for instance after PCFC) using IR or raman ?-
Unfortunately no, as we do not have the financial resources to carry out additional IR/Raman analysis on the chars produced from MCC or cone calorimeter samples.
table 2, from this table some values are different (check for instance the grey Llama merino pkHRR and THR values)-
The results are somewhat different, but many are within the 10% error of the technique. I’ve modified the text to comment that the cone calorimeter results cannot meaningfully discriminate between the fabric samples.
what is the standard deviation for values in table 4 ? is a difference of 0.8-04 in S significant ?-
As per ASTM D6413, section 14, regarding precision and bias for the technique, standard deviation for char length for machine woven fabrics is 0.566 inches. The standard deviation for hand-knit items has not been established. For afterflame times, the standard deviation is 0.23 seconds, again for machine woven fabrics. Some commentary on the data for Table 4 has been added to comment on what is and is not significant in the values recorded.
the densities of the fabrics are different, this could play a significant role, why the authors have selected samples with different densities ? is this a matter of availability ? have the authors selected the products that are more likely to be employed in the industry ?-
The reviewer is correct that the densities are different, but this is indeed a matter of availability. Some comments have been added to this paper to explain this issue. The products selected are all commercially available, and since hand-knit items are produced by individuals, not broad industrial use, they are representative of the types of knit goods that would be produced and used by consumers of these yarns. I’ve elaborated upon this point a bit in the introduction and in the experimental section and in the conclusions.
tables should be converted into a proper format-
All tables have been modified to match the format of the article template.
the number of figures should be reduced
The number of figures has been reduced and consolidated.
Reviewer 2 Report
The paper is entitled 'Flammability Characteristics of Animal Fibers by Breed: Single Breed Wools and Alpaca/Wool and Llama/Wool Blends’; however the paper is seems to be written in a hasty manner. Clearly the authors haven’t read the journals requirements and misplaced or rather neglected many parameters needed for a paper. The journal is obviously an open access, means many people will read it, the approach should be to make the paper presentable not complied to just get publication. This paper needs MAJOR revisions, which is obviously to start with. The novelty of paper can be found later.
Bear with the comments according to the line number;
The title needs to modified line # 1 to 4.
The university affiliation has been out of order.
he spacing between words are so obvious, it could be considered as doc to pdf conversion factor, but the authors should have seen the built pdf.
Why you didnt put all the sources of sample wool (sheep and llama) fibers in same pictures, doesnt need to make separate pictures.
The captions are just names.
The references are not well organized or rather didnt bothered to be followed according to journals requirements.
A part from the requirements of journal not being followed, the aim of the paper is missing. I think its very obvious that the heat release rate of wool fibers, regardless of their origins would be the same or similar. If the authors are looking for variations based on the composition of wool to be different, it needs to be defined.
Why the figures from Fig. 15 to Fig. 24 are not in similar context. If the authors aim to compare the before after test samples, they need to be in same figure.
Author Response
Thank you for taking the time to review this paper. The responses to each of the comments are given below in red color text.
Comments and Suggestions for Authors
The paper is entitled 'Flammability Characteristics of Animal Fibers by Breed: Single Breed Wools and Alpaca/Wool and Llama/Wool Blends’; however the paper is seems to be written in a hasty manner. Clearly the authors haven’t read the journals requirements and misplaced or rather neglected many parameters needed for a paper. The journal is obviously an open access, means many people will read it, the approach should be to make the paper presentable not complied to just get publication. This paper needs MAJOR revisions, which is obviously to start with. The novelty of paper can be found later.
Bear with the comments according to the line number;
The title needs to modified line # 1 to 4.
The reviewer was not clear in how they wanted the title to be modified. I have attempted to shorten it and make it more concise.
The university affiliation has been out of order.
I am afraid I don’t know how to answer this one. According to the template, the Organization goes first, then address. All of the authors are from the same organization.
he spacing between words are so obvious, it could be considered as doc to pdf conversion factor, but the authors should have seen the built pdf.
Again, I’m unsure how to answer this one. I did review the page proof, and it looked fine to me. I suspect the reviewer is referring to my habit, as taught to me decades ago, of putting two spaces after every period. I have gone through the document and removed this effect, but beyond that, I am unsure how to respond to this.
Why you didnt put all the sources of sample wool (sheep and llama) fibers in same pictures, doesnt need to make separate pictures.
My original intention was to make it easy for the readers to see images as they read. I’ve now condensed the images as best as possible.
The captions are just names.
I am unsure how to answer this. I believe captions for the figures and tables should be just names to keep it brief and not add lots of extra text to the paper. I didn’t see anything in the journal instructions to do otherwise.
The references are not well organized or rather didnt bothered to be followed according to journals requirements.
I have revised the formatting for all of the references as per the journal template. As for organization, the references are organized in the order they appeared first in the paper, and are cross-referenced as appropriate.
A part from the requirements of journal not being followed, the aim of the paper is missing. I think its very obvious that the heat release rate of wool fibers, regardless of their origins would be the same or similar. If the authors are looking for variations based on the composition of wool to be different, it needs to be defined.
I have added more information into the introduction section to explain why this study was carried out. I would argue that it was not obvious that wool fibers would be the same or similar regardless of origins, because the fibers from different breeds of sheep can be notably different in regards to texture, individual fiber shape, color, and how well they weave into textiles or are spun into yarns. I believe that there is value in confirming the assumption they are the same, and yet the paper shows that there are differences, albeit subtle, especially when the fibers are spun into yarns and are hand knit. I would concur that the work isn’t really breakthrough or extremely novel, but it was a piece of scientific information that was not present before this study was undertaken. If the reviewer still disagrees with the central premise of my paper, there isn’t much more I can do other than withdraw the paper from this journal as I am unsure what other reasons to give for the study other than what I’ve written so far. I am of course, open to specific points about what I’ve written that could be revised for clarity in case I have been unclear.
Why the figures from Fig. 15 to Fig. 24 are not in similar context. If the authors aim to compare the before after test samples, they need to be in same figure.
My original reason for separating the pictures as was shown in the original paper was because I felt it would be easier on the reviewer’s eyes to showcase the before and after pictures in higher magnification. I have consolidated those figures as per the reviewer’s request.
Reviewer 3 Report
Dear authors,
Your approach is original. Nevertheless, the number of knits and the differences between them (in terms of nature and structure) are too limited to draw meaningful conclusions.
At least this article can be used for future readers as a sum of interesting data about the flammability of animal fibers, but after taking into account the following comments.
About MCC: Please calculate the heat of complete combustion using THR and char yield. Add the mean values. The figures 8 are not clear and the meaning of the three pHRR is doubtful. Note also that for some knits there are two different fibers. Their decomposition overlaps but not perfectly. Therefore one apparent pHRR may be observed but due to the overlapping of two decomposition steps. This apparent pHRR cannot be compared to the pHRR of knits prepared from only one fiber type.
About cone calorimeter: Effective heat of combustion values are obviously wrong (the value is much higher than the value which can be calculated from MCC data). Please recalculate and correct. According to Figures 10 to 13, there are some differences in terms of HRR curve shape. The first pHRR is sometimes higher than the second one and sometimes almost undetectable. Please comment these differences. Unfortunately you have tested knits only at one heat flux. If tests have been carried out at several heat flux, more data could be obtained, and firstly the critical heat flux. If tests are still possible to perform, you could draw inspiration from Hernandez et al., Journal of Fire Sciences 36 (2018), 30-46.
In cone calorimeter, heat release rate is mainly driven by area density of thermally-thin samples. Several articles can be found about the influence of grammage. You pointed out this fact, but you cannot highlight this influence because your knits have similar characteristics.
Vertical Burning Test: It appears that the reproducibility of the test is worse. Please comment.
It is hardly possible to assess the better performance in vertical burning test to lower flammability as measured in MCC. Similarly the Sulphur content cannot be considered as responsible for lower flammability. Even if these assumptions are interesting to explore, for the moment you have only observed some correlations, from a very limited range of materials (“limited” because similar). At least please moderate these assertions.
Best regards
Author Response
Thank you for taking the time to review this paper. The responses to each of the comments are given below in red color text.
Dear authors,
Your approach is original. Nevertheless, the number of knits and the differences between them (in terms of nature and structure) are too limited to draw meaningful conclusions.
At least this article can be used for future readers as a sum of interesting data about the flammability of animal fibers, but after taking into account the following comments.
About MCC: Please calculate the heat of complete combustion using THR and char yield. Add the mean values.
This data has been added into the paper, and the relevant paper from Lyon has been cited as well.
The figures 8 are not clear and the meaning of the three pHRR is doubtful. Note also that for some knits there are two different fibers. Their decomposition overlaps but not perfectly. Therefore one apparent pHRR may be observed but due to the overlapping of two decomposition steps. This apparent pHRR cannot be compared to the pHRR of knits prepared from only one fiber type.
I agree with the reviewer that the decomposition of some of these materials do not overlap exactly and I’ve added some additional text to put the recorded peak HRR measurements into context as a range of values that can be expected for these types of materials.
About cone calorimeter: Effective heat of combustion values are obviously wrong (the value is much higher than the value which can be calculated from MCC data). Please recalculate and correct.
The results from the cone calorimeter are correct as reported and do not need to be recalculated as they were measured directly from the cone calorimeter experiments. The instrument was fully calibrated and operating correctly when the data was collected, and so the results are correct.
According to Figures 10 to 13, there are some differences in terms of HRR curve shape. The first pHRR is sometimes higher than the second one and sometimes almost undetectable. Please comment these differences.
Additional text has been added to hypothesize the reasons behind the irregular HRR curve shape for some of the samples.
Unfortunately you have tested knits only at one heat flux. If tests have been carried out at several heat flux, more data could be obtained, and firstly the critical heat flux. If tests are still possible to perform, you could draw inspiration from Hernandez et al., Journal of Fire Sciences 36 (2018), 30-46.
I agree, it would have been good to get critical heat flux (HRR0) and test these fibers at multiple heat fluxes, especially large heat flux/flash fires (85 kW/m2) to see if there was any other benefit. However, this project had limited yarns available and limited labor/testing resources since it was self-funded. Therefore these additional experiments cannot be carried out at this time.
In cone calorimeter, heat release rate is mainly driven by area density of thermally-thin samples. Several articles can be found about the influence of grammage. You pointed out this fact, but you cannot highlight this influence because your knits have similar characteristics.
I have deleted this conclusion from the paper and have simply stated that for radiant heat source tests such as the cone calorimeter, the materials are effectively the same.
Vertical Burning Test: It appears that the reproducibility of the test is worse. Please comment.
Text has been added on what our hypothesis is that would explain the irregular test results. We believe it is likely due to knit/fiber variation in the hand-knit items.
It is hardly possible to assess the better performance in vertical burning test to lower flammability as measured in MCC. Similarly the Sulphur content cannot be considered as responsible for lower flammability. Even if these assumptions are interesting to explore, for the moment you have only observed some correlations, from a very limited range of materials (“limited” because similar). At least please moderate these assertions.
I have gone through the paper to limit the conclusions of the work to better explain the limitations of the study with the limited number of fibers studied, and where no such conclusions can be made at this time – only further hypotheses.
Reviewer 4 Report
The premise for the work reported here is interesting. That there might be differences among protein fibers from different breeds of the same animal would not be expected (and the results presented here largely confirm that).
The manuscript needs some attention for clarity. For example, it isn't the differences between animal species but rather the differences between fibers from different animal species that was being studied. The fibers were not "studied in this paper" but rather in the laboratory, results are reported in the paper. Personal pronouns and starting a sentence with a number should be avoided. Corrections are penciled-in directly on pages of the manuscript attached. These are indicative of the kinds of changes needed throughout. In revision, care should be taken to say what is intended.
Comments for author File: Comments.PDF
Author Response
Thank you for taking the time to review this paper. The responses to each of the comments are given below in red color text.
The premise for the work reported here is interesting. That there might be differences among protein fibers from different breeds of the same animal would not be expected (and the results presented here largely confirm that).
The manuscript needs some attention for clarity. For example, it isn't the differences between animal species but rather the differences between fibers from different animal species that was being studied. The fibers were not "studied in this paper" but rather in the laboratory, results are reported in the paper. Personal pronouns and starting a sentence with a number should be avoided. Corrections are penciled-in directly on pages of the manuscript attached. These are indicative of the kinds of changes needed throughout. In revision, care should be taken to say what is intended.
I have made many of the changes the reviewer suggested, although some were addressed via other changes made in response to the other reviewer comments. I note that the attached document, which the reviewer was kind enough to include, only had the first 6 pages marked up. If there were other pages marked, they were not part of the document the reviewer sent. If the reviewer wishes to send the other pages, I’ll be glad to consider them. Due to comments made by other reviewers, I’ve taken more care to be clear about what was intended in this paper, and clarified some of the conclusions.
Round 2
Reviewer 1 Report
I’ve seen the authors answered almost all my previous queries and modified the manuscript accordingly, few questions remains as noted below:1 would it be possible to repeat the flame test for samples that showed completely different behavior (e.g. Llama/Merino Blend ) ?2 what is the standard deviation for values in table 4 ? is a difference of 0.8-04 in S significant ? this question refers to Elemental analysis table and not the char length.3 check the table format in the Instructions for Authors section (https://www.mdpi.com/journal/fibers/instructions)
Author Response
Thank you for taking the time to review the paper again. My responses to the three queries are as follows:
1) Unfortunately, we will not be able to conduct additional flame testing on the Llama/Merino blend as we are out of material. We tested in triplicate as per the ASTM method.
2) We do not know the % error for the method used to generate the data in Table 4. The company (Galbraith Labs) which conducted the elemental analysis did not report this information when they reported the results to us. However, I’ve calculated the standard deviation for the measurements provided. Based upon these calculated values, there does appear to be some variance within the samples themselves, but the % differences between some samples appears significant. Again, without knowing the exact error of the measurements, I’m speculating that the statistical analysis is meaningful here. I’ve added text to the analysis to comment on this.
3) I believe I’ve fixed the tables as per the template, but maybe I’ve missed something. If the reviewer sees a specific issue with the tables, please bring it to my attention and I’ll fix it.
Reviewer 2 Report
The paper has been revised well and is in much better format than the previous version. Unfortunately, while the present study is interesting, the authors have to read the journals required format prior submitting to it, the right way to add the university affiliation is ; University of Dayton Research Institute, Dayton, OH 45469, USA. Not, University of Dayton Research Institute, Dayton, OH USA 45469. This shows lack of focus and failure to adhere to the theme of journal. Anyway, best of luck.
Author Response
Thank you for helping point out how to fix the university affiliation. It has been changed.
Reviewer 3 Report
Dear authors,
You have addressed the issues pointed out by the reviewer. This article may be published as a preliminary report on the flammability of animal fibers-based textiles.
I would like to point out a result which is not discussed in the article. According to cone calorimeter tests, mass loss is quite low (around 25-30%) while mass loss in PCFC is much higher (75-80%). You should point out this difference. Moreover, it explains certainly why EHC in cone is much higher than in PCFC (despite that combustion is complete in PCFC). It seems that fibers are minimally processed. Maybe they contain components (animal fats and oils) releasing high heat and able to decompose earlier. Therefore, fibers fully decompose in PCFC but only a small fraction of fibers decompose in cone and this fraction is carbon-richer (and therefore heat of combustion is high).
Please comment and if needed, add a paragraph in the article. In all cases, the high EHC in cone calorimeter is intriguing.
Please read the text carefully to remove some grammar mistakes.
Please add units for FIGRA and comment MAHRE and FIGRA values (or delete them).
Sincerely
Author Response
Thank you for taking the time to review the paper again.
The reviewer has pointed out a finding that I had missed, and very likely is the explanation for the difference in PCFC vs. cone calorimeter EHCs. Additionally, the cone calorimeter utilizes a metal frame and grid which shields some of the sample from further decomposition. I’ve added additional text to explain these points in the cone calorimeter sections.
The reviewer may also be correct that these fibers may have some residual lanolin and other fats, but I cannot confirm this hypothesis. The vendors of these fibers did comment to me that they suspected the fibers had some residual lanolin and animal oils present based upon anecdotal experience with the fibers, but again, I cannot confirm this and I hesitate to speculate further based solely on anecdotal information.
I’ve checked the paper again for grammatical mistakes and I believe I’ve caught all of them, but, if I’ve missed any please let me know and I’ll fix them.
Units for FIGRA have been added to Table 2. Units for MARHE are already present in Table 2.
