Research Concerning the Bending Properties of Reconstituted Spruce Lumber Boards, Obtained by Edge-Cutting at 45° and Gluing
Round 1
Reviewer 1 Report
Dear editor
The writing of this paper is like a technique reported, especially for tables. they should be arranged in more efficient way. The density, MOE and MOR of spruce lumbers machined from two logs in were measured considering log length, loading directions, and compared with engineered spruce lumber glued in 45 degree. The critical point is that, after reading through the entire paper, nothing new was observed. All results drawn in this paper have been reported by others, not limited to those you cited.
Further comments and suggestions were marked in your manuscripyt, please see attachment.
Reviewer
Comments for author File: 
Comments.pdf
Author Response
COVER LETTER
Dear SIr,
First of all I wish to thank You for Your input and pertinent recommendations which helped us improve our article.
According to Your reccommendations:
- we brought changes to the title to be clearer and more suggestive;
- we improved the Introduction by adding a new reference (up-following refeernces were re-numbered accordingly); also, we added a more detailed explanation of the proposed solution, to underline the novelty character of the research performed;
- we added a figure of the product under study, to be more specific concerning its innovative character (this type of glued elements has not been studied before); up-following figures were re-numbered accordingly;
- we added more explanations in the method description, as required by the reviewers;
- we rearranged the tables containing the statistical interpretation of the results, according to the reviewer’s recommendations.
Please find below our answers concerning each of the issues raised in Your review.
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Answers to Reviewer 1:
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Rev (referring to Title): The abbreviations should not be included in title.
Done. After reading the reviews, it was obvious to us that the expression “conically-edged” was not a good choice and that it introduced confusion. Therefore, we changed the title into:
Research Concerning the Bending Properties of Reconstituted Spruce Lumber Boards, Obtained by Edge-Cutting at 45° and Gluing
In order to enhance better understanding, a figure was added (see new Figure 3), to be more explicite about how the tested product looked like. We hope that this also clarifies that the work has novelty character, since this type of joint has not been tested before.
Rev: Please check the paper titled "Characterizing Star-sawn Pattern–Produced and rthogonally Glued Specimens of Southern Pine". The edge-joint at 45 degree you called seems like to star-sawn lumber described in this paper.
Done. The lumber product obtained by the so-called “star-sawn pattern” (by Cao et al 2019) uses a totally different cutting pattern (radial cutting), which is technologically difficult to be achieved and it presumes, after gluing, several operations before a prismatic assortment is achieved. Also, it was tested only in delamination, without any reference to the bending properties.
We added this reference in the Introduction section (see lines 95-100), and we also pointed out how our method is different, technologically simpler and meant to valorize the sideboards (which would normally be classified as firewood). The advantages of the proposed sollution are listed in detail (see lines 101-109) which clarifies, we hope, why and how the proposed solution is of major interest for the industry.
Rev (referring to Table 1): What does "..." mean? It's not a formal type. Different MC should be separated.
This is how the values are given in the reference (Holzatlas 2008) - as minimum, mean and maximum value, separated by “...”. A short explanation was added in the title of Table 1 (see line 87) to clarify what the three values mean.
Rev (referring to dryer): The type of machine and corporation should be added.
Done. The type of machine (dryer) was added (see line 132); the corporation is Muhlbock.
Rev (referring to photo in former Figure 3): Highlight the glued lumber with a circle or an arrow.
Done. The photography used in former Figure 3, now Figure 4, was changed, to be more suggestive.
Rev: Do MOE and MOR measurements used the same samples?
Yes, the MOE and MOR measurements used the same samples (see added line 173)
Rev: You'd better draw a figure to indicate the position you referred.
We added a short explanation after Tables 3, 4, 5 (see lines 207-209) to explain the meaning of the position within the cross section, in relation with the already existing Figure 2.
Rev (referring to discussion after Table 5): The first and third point had been reported by many literatures. These are not new.
This is true, we just wanted to establish that the values we compare to (the values obtained for the unglued samples) are correct and reliable.
Rev (referring to the statement that solid wood samples shows that the tangential load leads to by 10% higher values of MOE and MOR compared to the radial loading): Why? Please explain it. As known, the strength of wood in radial direction is higher than in tangential.
With hardwoods it is true that the strength of wood in radial direction is higher than in tangential, but with resinous wood, the situation is different. The tangential cell walls of the tracheids contain only few or no pits; the wood is more rigid and opposes strongly to any load . Unlike these, the radial walls of the tracheids contain numerous pits, and so they are easily crushed. A brief explanation was added at lines 218-220.
Rev (referring to Table 6): The description of table is poor. Please modified referring to "Bolt-Bearing Yield Strength of Three-Layered Cross-Laminated Timber Treated with Phenol Formaldehyde Resin",
and referring to Table 7: Rearrange your table like what shown in "Bolt-Bearing Yield Strength of Three-Layered Cross-Laminated Timber Treated with Phenol Formaldehyde Resin".
Done. See new Tables 6 and 7.
Rev (referring to Conclusions): Did your study aim to verify former study? Your results should be compared with others, but what's new in you study, which is very important.
We eliminated the Conclusions referring to literature and we left just the conclusions which compare the properties of the glued elements to solid wood elements. The advantages of the proposed solution for the industry was emphasised (see lines 294-295).
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Hoping that our efforts to improve this article have brought it to a publish-able form, we look forward to your decision.
With kindest regards,
Prof. Mihaela Campean, on behalf of the authors - team
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript presents interesting research for improving wood cutting efficiency and use of all parts of less valuable tapered logs. But I think the methodology and results comments needs to be improved.
Title comments: “ Research Concerning the Density…”- how can the density be controled by cutting pattern? Maybe improve the title of the manuscript.
Also in title: “Conically-Edge Cut“- were sideboards really conically cutted? Or parallel cuted at 45 degrees? This is not clear in the rest of the text.
Line 30:… The target for sawmills is to get out the highest percentage..
Comment: Not just the volume, but also the highest values (profit)- this is not always the same.
Line 40:… The visual appearance of the final wood surface is also important, which requires best quality logs…
Comment: Not just the best logs, but also suitable cutting pattern/ cuts position.
Line 46, line 51- same sentence used twice: This means, that the logs are sorted into a box depending only on their quality, length, species and top diameter.
Line 100: …order to assess eventual differences of MOR and MOE depending on the position within the tree (top log vs. butt log)…
Comment: Top log vs butt log- but this logs were next to each other. And the total log was just 3m long. Shouldn’t you use logs from higher position in tree to compare and asses this?
Figure 2: after crosscutting- maybe use dashed line to show the 45 degree cut on thinner end- since the logs were tapered, there should still be much cut off on the wider end of log-or this were really conically boards as title suggests? But then board should be rotated (top/bottom) bo bond to parallel boards? And than comparison top bottom board is not possible?
Thickness of these sortiments cut from log?
Line 115- producer of this adhesive? Pressing parameters, temperature, time…Adhesive application rate g/m2?
Bending strength of glued boards- how did the break occurred? In glue line?
How this difference in moisture: “The measurement revealed values of 9.4-12.4% for the main (core and middle) solid wood boards, 12.6--13.9% for the solid wood sideboards, and 11.2-12.6% for the glued boards.” effects measured strengths?
Line 219:…the density of the bonded elements is higher than the density of the solid wood elements from the same (outer area) of the logs…
Comment: Explanation for this? Why is higher density on outer area?
Author Response
COVER LETTER
Dear Sir,
First of all I wish to thank You for Your input and pertinent recommendations which helped us improve our article.
According to Your reccommendations:
- we brought changes to the title to be clearer and more suggestive;
- we improved the Introduction by adding a new reference (up-following refeernces were re-numbered accordingly); also, we added a more detailed explanation of the proposed solution, to underline the novelty character of the research performed;
- we added a figure of the product under study, to be more specific concerning its innovative character (this type of glued elements has not been studied before); up-following figures were re-numbered accordingly;
- we added more explanations in the method description, as required by the reviewers;
- we rearranged the tables containing the statistical interpretation of the results, according to the reviewer’s recommendations.
Please find below our answers concerning each of the issues raised in Your review.
=======================
Answers to Reviewer 2:
=======================
Rev (referring to title): how can the density be controlled by cutting pattern and conically-Edge Cut“- were sideboards really conically cut? Or parallel cut at 45 degrees? This is not clear in the rest of the text.
After reading the reviews, it was obvious to us that the expression “conically-edged” was not a good choice and that it introduced confusion. Therefore, we changed the title into:
Research Concerning the Bending Properties of Reconstituted Spruce Lumber Boards, Obtained by Edge-Cutting at 45° and Gluing
In order to enhance better understanding, a figure was added (see new Figure 3), to be more explicite that the pieces were cut parallel at 45 degrees.
Rev (line 30): Not just the volume, but also the highest value (profit) is important.
Done. See new line 33.
Rev (line 40):Not just the best logs, but also suitable cutting pattern/ cuts position.
Done. See new line 43
Rev (line 46, 51): same sentence used twice
Done. We removed line 46.
Rev: Top log vs butt log- but these logs were next to each other. And the total log was just 3m long. Shouldn’t you use logs from higher position in tree to compare and asses this?
Done. We reformulated using lower and upper log instead of butt vs top log (see new line 121 and header in Tables 3-5).
Rev (referring to Figure 2): after crosscutting- maybe use dashed line to show the 45 degree cut on thinner end- since the logs were tapered, there should still be much cut off on the wider end of log-or this were really conically boards as title suggests? But then board should be rotated (top/bottom) bo bond to parallel boards? And then comparison top bottom board is not possible?
We introduced new Figure (Fig. 3) to be more specific.
Rev: Thickness of these sortiments cut from log?
Done. It is now specified in lines 127-128.
Rev (referring to line 115): Producer of this adhesive? Pressing parameters, temperature, time…Adhesive application rate g/m2?
Done. See lines 138-141.
Rev: Bending strength of glued boards- how did the break occurred? In glue line?
The breaking occurred in wood. The glue line was not affected. We added this explanation in the text as well (see rows 239-2240).
Rev: How this difference in moisture: “The measurement revealed values of 9.4-12.4% for the main (core and middle) solid wood boards, 12.6--13.9% for the solid wood sideboards, and 11.2-12.6% for the glued boards.” affects measured strengths?
It is a known fact that the moisture content affects negatively the MOR and MOE. This is why, in order to be compared, the MOR and MOE values were compensated (recalculated) according to the standard-specific formula, as for mc=12% (this is already mentioned in the text, in rows 180-184). According to the standard this is eligible as long the individual values fit within (12 ± 5)% and this condition is respected.
Rev (referring to line 219): the density of the bonded elements is higher than the density of the solid wood elements from the same (outer area) of the logs ?
Yes, because of the adhesive. We added this explanation in the text as well (see row 227).
Rev: Why is higher density in outer area?
The density is higher in the outer area because the width of the annual rings (and the proportion of earlywood) decreases from core to bark. The inner part (core zone) contains wide annual rings (3-4mm), with high proportion of earlywood. Towards the outer zone, the annual rings become narrower.
We added this explanation in the text as well (see rows 213-215).
=======================
Hoping that our efforts to improve this article have brought it to a publish-able form, we look forward to your decision.
With kindest regards,
Prof. Mihaela Campean, on behalf of the authors - team
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear authors
WIth the revised manuscript you resubmitted, shows the deligence and patience on correction. The manuscript had been improved so much on this version. I recommended that it can be published in this version. Congratulations. In addition, i am interested in this sentence "this can be explained by the much lower number of pits in the tangential than in the radial walls of the tracheids, which makes resinous wood more resistant 212 to tangential loads", are there any references available, or do you have SEM or other microscope photos to support this statement?
Author Response
Dear Sir,
Many thanks for the kind words of appreciation and for giving the green light to our manuscript.
Regarding the statement concerning the cell walls and number of pits in tangential and radial cell walls of resinous timber, I hereby attach two images from the personal archive of the prime author (Porojan, M). They are part of a faculty project, in which we developed an electronic catalogue of wood species (with multiple authors), but it was not published yet, therefore we could not able to include these photos in the paper.
Once again many thanks for your support, with kindest regards,
Mihaela Campean
Author Response File: Author Response.pdf
Reviewer 2 Report
Figure 8- still have top/butt marks for parts of the log. Since you changed this is previous tables to lower and upper-maybe you should use here the same terms.
Line 267: The proposed solution enables increasing the lumber yield from tapered logs, with minimum changes to the existing technology.
Do you have any estimate, how much would the yield changed?
Author Response
Dear Sir,
Many thanks for your pertinent observations.
We corrected Figure 8.
Regarding your question concerning the yield increase: according to our calculations up-to date this is 80-85% for logs with 7mm/m taper. The present research is part of a PhD-Thesis elaborated by PhD Student Brandstetter Markus which follows to be defended, and this is why we chose not to give a concrete yield value before the study is ended. We very much count on your understanding.
Many thanks for all your support, with kindest regards,
Mihaela Campean
