Behaviors of Bubbles Trapped in Film Coating during Spray Gun Coating and Its Influences on Coating Defects

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper describes the behavior of the bubbles entrapped in the film during the spray coating process for water-borne coatings. However, I believe the overall article can be improved. Here are some of my comments:

- The paragraph on VOCs seems abrupt in the introduction

- The two reasons in lines 131-136 need more scientific backing from literature and explanation. Why would some bubbles burst outwards and some dissolve downwards?

- In relation to the second reason, would these small bubbles collapse and form large ones to minimize surface energy instead of dissolution?

- Including the impact of temperature and humidity on the bubble formation and dissolution would widen the impact of the paper.

 

Comments on the Quality of English Language

Needs moderate editing for English.

Author Response

We sincerely appreciate your detailed review of our paper. We attached the response file for your comments and questions. Thank you for your help.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In this paper, the authors investigated the behavior of bubbles entrained in a film coating during 8 spray coating. Air bubbles that remain in a film coating after diluent evaporation cause coating defects called bubbling defects, including fish-eye and crater defects. In this study, visualization of a film coating revealed that smaller bubbles in the film shrank slowly and disappeared while larger bubbles remained. Some minor issues should be addressed:

 

(1) Page 4, Line 131-133, "The bubbles disappeared for two reasons. First, the bubbles trapped in the film coating floated to the surface and were released from the surface into the atmosphere. This was confirmed by the observed bursting and disappearance of the bubbles during film coating formation.", the authors are suggested to explain it much more detaily;

 

(2) Page 6, Line 165-167, "As explained in Section 3.2, the smaller bubbles shrank and disappeared more quickly, whereas the relatively larger bubbles shrank more slowly; after some time, only the middle-sized 167 bubbles remained.", the authors are recommened to provide more description；

 

Over all, the paper is well organised and can be accepted after minor reversion.

Author Response

We sincerely appreciate your detailed review of our paper. We attached the response file for your comments and questions. Thank you for your help.

Author Response File: Author Response.docx