The Performance Optimization of Oriented Strand Board Veneer Technology

Round 1

Reviewer 1 Report

1. Line 45

[8] used Hunan phyllostachys pubescen as a material to develop BOSB

better: 

[8] used bamboo from Hunan province (Phyllostachys pubescens)  as a material to develop BOSB

Thank you for your comment. The sentence is corrected in the revision.

2. Line 59 – citation writing not correct

Barbara has conducted = change to - Ozarska has conducted

because Barbara is the 1st name of Ozarska

Correct writing of this citation in References is:

Ozarska, Barbara. (2014). A Manual for Decorative Wood Veneering Technology.

Yes. The citation writing is mistaken. We have changed in the revised version.

3. Line 62 wrong citation [14] please find another article to support your statement about formaldehyde pollution

“However, the large utilization 62 of these adhesives has caused serious formaldehyde pollution problems [14].”

 I have read this article [14] , there is nothing about formaldehyde pollution 

[14] Jiang, J., Lu, X. Improving characteristics of melamine–urea–formaldehyde resin by addition of blocked polyurethane prepolymer. Eur. J. Wood Prod. 75, 185–191 (2017). https://doi.org/10.1007/s00107-016-1132-0  - REPLACE IT WITH ANOTHER ARTICLE ON FORMALDEHYDE POLLUTION

Yes. The citation is wrong. We have changed it to be a correct one as follows:

[18] Godish T. Indoor air Pollution Control, Michigan: Lewis Publishers Inc, 1989.

[19] Wi S , Kim M G , Myung S W , et al. Evaluation and analysis of volatile organic compounds and formaldehyde emission of building products in accordance with legal standards: A statistical experimental study. Journal of Hazardous Materials, 2020, doi: 10.1016/j.jhazmat.2020.122381.

Line 66

Among them, the research of biomass adhesive based on soy protein is a widely studied biomass adhesive [15].

wrong English

Correct could be: Adhesive based on soy protein is a widely studied biomass adhesive [15].

4. Line 69  suiTable correct : suitable

Line 70

However, due to the bonding strength, water resistance, poor product stability, and high price of soybean protein adhesive, its application is limited

better:

However, due to the low bonding strength, low water resistance, poor product stability, and high price of soybean protein adhesive, its application is limited

Thank you for your comments. The typos and mistakes are corrected in the revision.

5. Line 80

Adhesive: The prepared cornstarch adhesive has excellent adhesive performance, and all indexes meet the requirements

Please provide more details about the performance and the indexes. There should be more information about the adhesive, its preparation and properties like solid content, density, viscosity, gel time.

We have added more information of our adhesive as follows:

The solid content ≥ 30%, the storage period ≥ 100d, the pH value is 6–7, and esterification degree is 0.0166–0.0300.

6. Line 140

The veneer penetration rate of the veneer

 better

The veneer penetration rate.

Thank you. The presentation is changed in the revision.

7. Line 145

necessary to observe the situation of permeation of the board directly

Question: How the observation was done? Was the methodology suitable? Check the article below article to be better informed about methodology of estimation of the penetration

Mohd Nazip Suratman, Adhesive Penetration in Laminated Oil Palm Trunk Veneer, October 2013 Journal of Tropical Forest Science 25(4):467-474

Thank you for your comment. Because penetration refers to the discoloration of the surface of the base material due to the penetration of the glue layer, it is necessary to destroy the whole wood or use a scanning instrument to determine the penetration of the cornstarch adhesive inside the wood. In this paper, we measure the ratio of discolored veneer area to total veneer area as the penetration. The average veneer penetration rate (VPR) of tested n boards can be described as:

where s_p is the size of discolored veneer area, the S_i represents the total size of the i-th board.

In [28], three different values are considered: effective penetration (EP), average penetration (AP) and maximum penetration. Among them, the calculation of EP is:

where A_i = area of cured adhesive (µm), n =number of cured adhesive and x_o = width of the maximum rectangle defining measurement area.

We have also referred to the recommended paper for detailed introduction of the situation of permeation of the board.

The calculation of EP is similar to our method. Compared with the calculation method in [28], our calculation method still has room for improvement. However, this is not our research focus in this article, and will be further improved in our subsequent research.

[28] Mohd Nazip Suratman, Adhesive Penetration in Laminated Oil Palm Trunk Veneer, October 2013 Journal of Tropical Forest Science 25(4):467-474.

8. From the five experiments,

Question: How many experiments were performed for one point shown in the diagram ? Did you estimate standard deviation?

Thank you for your comment. Actually, all the experiments in the paper are repeated three times. Some details of the statistical treatment are added in the revision.

We have added the following sentences in the revision:

In this section, the experimental processes are given. Note here that, all the experiments in this paper are repeated three times and average value of all the statistical results are taken into consideration.

Yes, we have estimated the standard deviation.

We have added the description of the standard deviation in the revision as follows:

Each value of the point in Figure 4 is the average of three experiment. The average and standard deviation of these experiments are 0.758±0.0026, 0.784±0.0050, 0.856±0.0021, 0.821±0.0031, and 0.703±0.0046, respectively.

9. Table 5. Range analysis of surface bonding strength.

Table 6. Range analysis of veneer penetration rate.

Opinion: The range analysis is for me not clearly described; what are K1, K2, K3 and k1,k2, k3?

Thank you for your comment. Ki is the sum of the total strength or the penetration rate related to level i. The average ki reflects the influence of the level i on strength or the penetration rate. This has been described in detail in the revision.

We hope that our explanations have satisfied the reviewer’s concerns.

Again, we really appreciate the reviewer’s helpful comments on our paper. Thank you.

Reviewer 2 Report

This paper deals with the investigation of the influence of two different manufacturing techniques and relevant process parameters for coating a wooden oriented strand board (OSB) with a valuable wooden veneering material. Some experiments are conducted and a DoE (probably L9 Taguchi orthogonal array) is carried out to identify the optimal values of the involved parameters.

Veneering itself can be considered a decorative “coating” technique, complying with the topics of the Journal, it is an interesting topic for the industrial sector and it is surely worth to be investigated. The paper has a strongly industrial and technical slant, but lacks scientific rigour for several reasons, argued below.

English language needs a revision, in particular aiming to uniform verbal tenses.

From the scientific standpoint, the paper is quite simplistic and the significance of the findings appear somewhat modest, inasmuch a statistical interpretation is completely absent. The Authors declare they adopted the orthogonal experimental design, but they do not provide any conceptual justification about the applicability of this method in this case to the system under exam. The basis on which the hypothesis of complete independence of the variables is declared, should be provided and the procedure, the software used and the mathematical model followed to correlate the experiments and to infer the results should be at least outlined.

1. Were the experimental tests reported in Table 3 replicated? I see that experiments in Table 1 (cold pressing) and with the hot pressing technique are replicated 3 times for each aging time (which is not included in the parameter table of the DoE and it is not clear its role in it), but no mention about the repeatability of experiments in Table 2 is given. Furthermore, the statistical treatment of the corresponding results is almost completely inexistent, thus arising licit doubts about the robustness and the reliability of the results themselves.

Thank you for your comment. Actually, all the experiments in the paper are repeated three times. Some details of the statistical treatment are added in the revision.

We have added the following sentences in the revision:

In this section, the experimental processes are given. Note here that, all the experiments in this paper are repeated three times and average value of all the statistical results are taken into consideration.

2. The Introduction is very limited, only 21 citations are reported (out of which, only 16 refer to scientific works) and a deep literature review is missing. Even though some general aspects are discussed, no rigorous and all-encompassing analysis of the state-of-the-art is detected, in which all the manufacturing issues and mechanical properties of veneering techniques are thoroughly examined. These aspects deserve a broader analysis and literature review, since a vast literature is available about the topic.

Thank you for this comment. We only record the most representative articles, so the number of references is limited. This does have a bad impact on whether the paper has a broader analysis and literature review of the field. So, a deep literature review is given in the revision.

3. The Authors state: “In comparison, cornstarch adhesive has a better application prospect.”. It being understood that the Introduction generally requires a substantial revision, no literature review about cornstarch is provided. Indeed, several studies investigate the beneficial properties of this kind of adhesive, due to its pollution-free peculiarity, regarding formaldehyde. I particularly recommend a thorough literature overview about this topic, which is well-known and it appears as one of the core focuses of the paper. I mainly refer, for instance, to the papers (not so recent) by the Authors Moubarik, A., Allal, A., Pizzi, A., Charrier, F., & Charrier, B. (2010), published in the European Journal of Wood and Wood Products and further works of the same group, but also Yang, C., & Wang, R. Z. (2008). Preparation of modified corn starch adhesive for plywood [J]. Adhesion in China.

Thank you. The references recommended are suitable. We have referred to these papers in the revision.

4. Line 88: are such values adopted to follow some relevant guidelines or rather arbitrary? Please specify.

Thank you for your comment. The reason for that is as follows: because cold pressing is carried out at room temperature, it usually takes a long time to make the surface bonding strength meet the requirements. So we choose the value settings to make the result comparable and meaningful.

 5. Lines 95 – 96: “Operations illustrated in Figure 1 are substrate sawing, substrate sanding, veneer splicing, substrate coating, adhesive utilization, veneer overlaying, aging, cold pressing, placing, trimming.”. This sentence is redundant, since simply repeats what clearly shown by Figure 1. Authors should rather develop the most significant steps with a short explanation of the procedure and/or some photos/pictures. The same consideration holds true when the hot pressing procedure is explained (lines 112-113)

An in-depth explanation of the “aging” procedure is missing. Evaluated the crucial role played by aging, conditions and a brief literature overview should be rigorously detailed within the experimental part and the introduction, respectively.  Maybe do the Author mean “curing” of the adhesive? Usually “aging” refers to degrading treatments.

Thank you for your comment. The process is revised as follows:

After cutting the OSB base material into the size of 50mm × 50mm, sanding the surface to make the surface flat and easy to stick the veneer, then sticking the veneer on the base material surface, aging for 30min, cold pressing / hot pressing experiment, checking the veneer adhesive quality after cold pressing / hot pressing, placing for 72h, making the adhesive fully solidified, finally trimming with a paper cutter, polishing the edge of the OSB with sandpaper.

This description is added in the revised version.

Besides, the main purpose of aging is to make the adhesive liquid infiltrate and lose water, so as to improve the bonding strength, generally after the veneer is attached to the surface of the base material, before cold or hot pressing. The curing of adhesive is after cold pressing or hot pressing.

6. Section 2.2.3: the test procedure to determine the mechanical behaviour (namely the “surface bonding strength”) is not disclosed and thus appears unclear. Which is the testing set-up and protocol? It is not rigorous.

According to [24], test method for surface bonding strength is designed as follows:

Figure. 1 shows the flow chart of surface bonding strength test.

(1) Sawing test piece: cut the veneered OSB into the test piece with the size of 50mm × 50mm;

(2) Drawing line: draw a small square of 20 mm × 20 mm in the center of the sawed specimen with color;

(3) Gluing the square iron block: use the hot-melt adhesive to glue the front (the side with circular groove) of the customized square iron block upward in the center of the test piece;

(4) Placing: place the piece to be cold;

(5) Cutting: cut the decorative layer along the periphery of the square iron block with a hand hacksaw to the surface of the base material;

(6) Testing: fix the test piece on the universal mechanical testing machine with the chuck and fixture, load it in the direction perpendicular to the glued surface, and record the gluing strength of the test piece from the beginning of loading to the failure of the test piece.

This part has been added into the revision.

[24] GB/T 17657-2013. Test methods of evaluating the properties of wood-based panels and surface decorated wood-based panels. State General Administration of the People’s Republic of China for Quality Supervision and Inspection and Quarantine; 2013.

7. Section 2.2.4 and Table 4: are such intervals endorsed by some guidelines? The penetration rate evaluation is not clear. How do the Authors measure it? Do they use a particular instrumentation? This reviewer cannot understand this sentence: “It is difficult to calculate the specific area of permeation, so it is necessary to observe the situation of permeation of the board directly when performing the permeation statistics”

Thank you for your comment. Because penetration refers to the discoloration of the surface of the base material due to the penetration of the glue layer, it is necessary to destroy the whole wood or use a scanning instrument to determine the penetration of the cornstarch adhesive inside the wood. In this paper, we measure the ratio of discolored veneer area to total veneer area as the penetration. The average veneer penetration rate (VPR) of tested n boards can be described as:

where s_p is the size of discolored veneer area, the S_i represents the total size of the i-th board.

8. Line 162 “The cornstarch adhesive has good initial viscosity and good precompression”. “good” is a subjective characterization. Please provide objective information, possibly correlated with similar researches available in the literature.

Thank you. The description is not subjective. We showed the standard in section 2.1 Materials and equipment as follows:

Adhesive: The prepared cornstarch adhesive has good adhesive performance, and all indexes meet the requirements of GB/T 20241-2006 [26] and GB/T 14074-2006 [27].

We also have added more information of our adhesive as follows:

The solid content ≥ 30%, the storage period ≥ 100d, the pH value is 6–7, and esterification degree is 0.0166–0.0300.

9. Lines 163 – 164: “if the aging time is too long, the degree of curing will become stronger, the viscosity will become smaller”. Does aging, and therefore an increased curing degree, reduce the viscosity? I would rather expect the opposite, as it usually occurs for polymers during polymerization reactions, when macromolecules arrange in more rigid networks. I could be mistaken, but please discuss it. Moreover, how adhesive viscosity affects strength? No experimental investigations or links to similar evidence in the literature are provided to endorse the viscosity strength correlation.

Thank you. The aging phase is before the cold pressing / hot pressing operation. So, if the aging time is too long before the cold pressing and hot pressing, the adhesive layer could have solidified, which will reduce the bonding strength of the veneer and the substrate surface.

Besides, [1] presents the relationship between adhesive viscosity and strength. However, in our paper, the adhesive viscosity and strength are two separated recorded observation index.

[1] Emengo F N , Chukwu S E R , Mozie J . Tack and bonding strength of carbohydrate-based adhesives from different botanical sources[J]. International Journal of Adhesion & Adhesives, 2002, 22(2):93-100.

10. Lines 177-178 “the utilized cornstarch adhesive has good initial viscosity and fast bonding speed”. Apart from the adjective “good”, already discussed, the concept of “bonding speed” is not clear and not explained in the manuscript.

Yes, the concept of “bonding speed” is not clear. According to [27], The bonding speed means that the requirements of the combination strength can be met in a short hot pressing time. Additionally, this part has been deleted in the revision for a clearer experiment description.

[27] GB/T 14074-2006. Testing methods for wood adhesives and their resins. State General Administration of the People’s Republic of China for Quality Supervision and Inspection and Quarantine; 2006.

11. Lines 190 – 192 “From Table 5, some conclusions can be drawn intuitively: OSB is sanded and pasted with 0.6mm Burmese old mahogany. Cornstarch adhesive is used for hot pressing.” It is not a conclusion, just a recap of the manufacturing procedure, that is not relevant here.

Thank you. This sentence is deleted. The detailed conclusion has been drawn out in the manuscript as follows:

From the relationship of RA> RB> RC, we can draw the conclusion that factor A (unit pressure) has the largest influence on the bonding strength, followed by factor B (hot pressing temperature), and finally factor C (hot pressing time).

12. Line 193 – 194 “The range R reflects the influence of various factors on the experimental results. Range represents the magnitude of the numerical fluctuation”. This is an unclear definition of the parameter R that should be clearly and analytically defined in the experimental section.

Thank you for your comment. Range R is the difference between the maximum and the minimum number in ki. If the range is bigger, the changes of the values of these factors in the experimental range will lead to greater changes in the experimental indicators. So the column with the greatest range is the one with the greatest influence of the level of factors on the experimental results, that is, the most important factor.

13. Tables 5 and 6: what do K1, K2, K3, k1, k2, k3 stand for and how are they computed? It is to be specified thoroughly.

Thank you for your comment. Ki is the sum of the total strength or the penetration rate related to level i. The average ki reflects the influence of the level i on strength or the penetration rate. This has been described in detail in the revision.

We hope that our explanations have satisfied the reviewer’s concerns.

Again, we really appreciate the reviewer’s helpful comments on our paper. Thank you.

The experimental part is very confused in some points: This reviewer is not able to figure out a clear experimental scheme. Explicative images, photos, clearer explanations are required. Besides, the mechanical test procedures (surface bonding strength measurements) are declared nowhere.

Finally, the main target of the paper is not clear to me. Do the Authors want to emphasize the role of an eco-friendly adhesive in a well-established manufacturing process? Do the Authors put in emphasis two different manufacturing techniques, namely cold- and hot-pressing? Or are the parameters for the hot-pressing technique rather the focus of the paper?

To sum up, the scientific rigour is not adequate to the required standards of the Journal. Some detailed remarks are reported in the attached file, which may hopefully be useful for the Authors in the revision of their paper.

I warmly encourage the Authors to thoroughly improve their work, given the valuable efforts they spent in conducting tests.

Unfortunately, in my opinion the paper presents serious methodological flaws and therefore is not suitable for publication in “Coatings” Journal.

Round 2

Reviewer 1 Report

Thank you for the improvement done.

Please correct additional

1.line 177 Mpa -> MPa

Thank you for your comment. All the MPa are correct in the revision.

2. The titles of Tables 5 and 6 are the same, please add: cold pressed or hot pressed, respectively

Thank you. The title of Table 5 is “Range analysis of surface bonding strength” and that of Table 6 is “Range analysis of veneer penetration rate”. Both of the two experiments are tested under hot pressed, which has been described in the content.

3. Please combine discussion of results presented in the Tables 5 and 6 to avoid repetitions (Line 202 and 230)

Thank you. We have combined the discussion in the revised version.

4. Correct this conclusion: (2) The comparison between hot pressing and cold pressing shows that hot pressing on the  surface bonding strength (what is the influence of hot pressing?)

Thank you for your comments. We have revised the conclusion as follows:

The comparison between hot pressing and cold pressing shows that hot pressing on the surface bonding strength. The high pressing temperature during the pressing increases the movement of the molecules, which in turn speeds up the improvement of the bonding strength.

We hope that our explanations have satisfied the reviewer’s concerns.

Again, we really appreciate the reviewer’s helpful comments on our paper. Thank you.

Reviewer 2 Report

The Authors have addressed my concerns.

1. Unfortunately, English language still requires a thorough revision, possibly by a native speaker, to improve the fluency of presentation and facilitate reading.

Thank you for your comment. We have improved the fluency of some presentation in the revision.

2. Again, the Authors declare they adopted the orthogonal experimental design, but they do not provide any conceptual justification about the applicability of this method in this case to the system under exam. Orthogonal DoE is founded on precise bases and it is adopted for specific purposes. It is advisable to provide some additional information to the reader about the arguments of the choice of this particular experimental design.

Thank you for your comment. The orthogonal experimental design [24] is adopted in the experiment. Orthogonal experimental design is an efficient method for the analysis of multi-factor and multi-level problems and has been widely utilized in many furniture related research [28, 29].

The additional expression of the reason to adopt the orthogonal experimental design in our research has been added to the revision.

[24] GB/T 17657-2013. Test methods of evaluating the properties of wood-based panels and surface decorated wood-based panels. State General Administration of the People’s Republic of China for Quality Supervision and Inspection and Quarantine; 2013.

[28] Chen M, Lyu J. Properties of double dowel joints constructed of Medium Density Fiberboard. Maderas. Ciencia y tecnología, 2018, 20(3): 369-380.

[29] Li M, Cao Y, Wang Z, et al. Optimization and analysis of processing paraments of wooden crafts based on ultra-high pressure water jet method. Wood Research, 2018, 63(1): 117-126.

3. Fig.6: VPR in the y-axis should be unit-less (or perhaps a percentage), according to the definition given in Eq.2 (line 167).

Thank you. The y-axis should be unit-less. We have corrected the mistake.

4. The added sentence in line 262 (Conclusion no.2). This sentence in its present form makes nonsense and needs rewording

Thank you for your comment. The conclusion no.2 is revised as follows:

The comparison between hot pressing and cold pressing shows that hot pressing on the surface bonding strength. The high pressing temperature during the pressing increases the movement of the molecules, which in turn speeds up the improvement of the bonding strength.

We hope that our explanations have satisfied the reviewer’s concerns.

Again, we really appreciate the reviewer’s helpful comments on our paper. Thank you.