Effect of Protective Coatings on Wooden Elements Exposed to a Small Ignition Initiator

Round 1

Reviewer 1 Report

Gašpercová and colleagues monitored the behavior of various wood species exposed to a small ignition source for 10 minutes. They found that the flame spread within 30 seconds was significantly dependent on the type of tree species tested. Oak samples demonstrated the most promising results in terms of flame retardancy, particularly when combined with a fungicide coating. The effectiveness of the retardants varied in their impact on the final values of mass loss and flame spread. Overall, the BOCH FUN sample showed the most favorable outcomes, regardless of the wood species used. This work is interesting for the readers of the Applied Sciences. However, the following comments should be addressed before the manuscript can be published.

1.      Although existing wood fire-retardant coatings can partially slow down the burning process, their effectiveness under high temperature and high humidity conditions, where the application effect may not be optimal, is questionable. How do the materials being evaluated perform in such environments?

2.      The effectiveness of fire-retardant coatings is directly related to their quality and stability. Can you provide data on the quality and stability of the coatings under discussion?

3.      Typically, the production cost of conventional fire-retardant coatings for wood is deemed expensive. In comparison, how do the costs of the coatings discussed in this study compare to those of commercial counterparts?

4.      Wood fire-retardant coatings are primarily employed in indoor decoration materials, furniture, and other related areas. How effective are these coatings in outdoor building applications?

5.      There are too many figures included in the manuscript, can the author rearrange the figures by putting similar data/figures together?

Author Response

Thank you for the helpful comments we have incorporated into the article. We believe that editing the article has made the article better.

I would like to apologize for the errors.

Our new comments in article are highlight of green colour.

Answer to point 1:

We added new text:

Each of the studied fungicidal coatings can be used in indoors (roof structures, floors) and outdoors (roof underlayment, fences, pergolas) [48-52]. The prepared wood samples with fungicidal coatings were stable. The modified surface kept its smooth shape, did not change its color and consistency.

Manufacturers [48-52] guarantee washout resistance. High moisture or loading of the coating with water and snow will not affect the quality of the fungicidal coating. Exposure of the product treated with fungicidal coating to high temperature is not indicated by the manufacturer.

The used flame retardant HRR can be used both indoors and outdoors and cannot be washed off after drying. HRR can be used on material exposed to water, snow and in high moisture environments. The manufacturer [53] indicates the resistance of the treated product by HRR to temperatures higher than 1700 ºC, then blackening of the surface of the sample occurs and the fire does not spread.

Answer to point 2: we also adde new text

The application of coatings to the samples was based on the manufacturers' recommendations. The application is determined in the technical specification supplied together with the coating [48-52]. Coatings were applied using a brush. Verification of the amount of received protective wood coating was carried out for each sample separately by monitoring the amount of used coating sample before and after painting. The difference in the observed values indicated the reception of a sufficient amount of coating, of course, in accordance with the values set by the manufacturer.

Answer point to 3: we added information about price:

The price of protective coatings varies depending on the seller and the size of the package. A 1 kg package of HRP costs around 25-39 euros, a 5 kg package of HRP costs around 87-140 euros. The price of fungicidal coatings is also very different, but they are cheaper than HRP. The prices of fungicidal coatings are approximately one-third the price of HRP. A 1-liter package of fungicidal coating costs around 9-13 euros, a 5-liter package costs 30-50 euros [49].

Answer to point 4:

We tried to explane your comments follow:

In its tsafety sheet, the manufacturer specifies the use of HRP in the exterior as well as in the interior.

Our research confirms this fact. Our experiment was carried out for 8 months. The samples were painted with protective coatings and placed indoors (the first half of the samples) and outdoors (the second half of the samples). All samples were exposed to a flame for 30 minutes after 8 months. The obtained results of weight loss and speed of flame spread over the surface were the same. The HRP coating applied to the samples placed in the exterior was of the same quality as the coating applied to the samples placed in the interior. This research will be the subject of another scientific article, which will be published in the near future.

Answer to point 5: Thanks for comment, we tried to edit it.

Reviewer 2 Report

Stanislava Gašpercová, Iveta Marková, Miroslava Vandlíčková, Linda Makovická Osvaldová and Jozef Svetlík

Effect of protective coatings on wooden elements exposed to a small ignition initiator

Appl. Sci. 2023, 13, x. https://doi.org/10.3390/xxxxx

In the paper, the authors presented the monitoring of the behavior of selected wood species exposed to a small ignition initiator. The main goal of the work was to investigate the effect of retardant coating on the combustion process of the wood species: spruce (Picea abies), red spruce (Larix decidua), scots pine (Pinus sylvestris), ash (Fraxinus excelsior L.), beech (Fagus sylvatica) and oak (Quercus robur) exposed to a small initiator of ignition.

Detailed comments:

1.      The choice of samples and the execution of the coating does not raise any objections.

2.      Determination of the Ignitability of Wood Samples by the Action of a Small Ignition Initiator was conducted correctly.

3.      The description of the axis in Figure 4 is not legible. The fonts are too small. In addition, the descriptions of Figure 4 in the text and under the figure are inconsistent. Authors should consistently use the term mass instead of weight.

4.      Before one-way ANOVA analysis, did the author control the normal distribution of the mass loss and flame spread dependence for each wood species? Please post it.

5.      Figure 6, 8 was carelessly prepared. What does mustache mean?

The work is interesting, but in its present form, it should be kept from being published.

Author Response

We thank the reviewer for valuable advice and comments that contributed to improvement of the quality of the article.

Answer point 3:

We made correct „mass“ in whole text.

Answer point 4

Before one-way ANOVA analysis, we controlled the normal distribution of the mass loss and flame spread dependence for each wood species, because we realised normal distribution for multiplicity n < 10. In the given case of a normal distribution of the multiplicity (frequencies) of the set, the median is the same as the arithmetic mean.

Answer point 5

Boxplots have mustaches. One mustache represents whole mass loss values for wood samples for 1 protectived coating in Fig. 6

One mustache represents whole flame spread values for wood samples for 1 type protectived coating in Fig. 8

Boxplot uses to assess and compare the shape, central tendency, and variability of sample distributions and to look for outliers. In a typical box plot, the top of the rectangle indicates the third quartile, a horizontal line near the middle of the rectangle indicates the median, and the bottom of the rectangle indicates the first quartile. A vertical line extends from the top of the rectangle to indicate the maximum value, and another vertical line extends from the bottom of the rectangle to indicate the minimum value. The illustration shows a generic example of a box plot with the maximum, third quartile, median, first quartile, and minimum values labeled. The relative vertical spacing between the labels reflects the values of the variable in proportion.

Round 2

Reviewer 2 Report

The work has been significantly improved and supplemented. In addition, the comments of the reviewers were taken into account, which had a positive impact on the quality of the study. It should be emphasized, however, that the X and Y axes descriptions in the figures still need to be of better quality. So, the work requires editorial correction.

Author Response

We thank the opponent for a thorough check.

We made adjustments to the axes "x" and "x" in Fig.6 and Fig. 8.