Coating

Lacquer being sprayed onto a cabinet

A coating is a covering that is applied to the surface of an object, or substrate.[1] The purpose of applying the coating may be decorative, functional, or both.[2] Coatings may be applied as liquids, gases or solids e.g. powder coatings.

Paints and lacquers are coatings that mostly have dual uses, which are protecting the substrate and being decorative, although some artists paints are only for decoration, and the paint on large industrial pipes is for identification (e.g. blue for process water, red for fire-fighting control) in addition to preventing corrosion. Along with corrosion resistance, functional coatings may also be applied to change the surface properties of the substrate, such as adhesion, wettability, or wear resistance.[3] In other cases the coating adds a completely new property, such as a magnetic response or electrical conductivity (as in semiconductor device fabrication, where the substrate is a wafer), and forms an essential part of the finished product.[4][5]

A major consideration for most coating processes is controlling coating thickness. Methods of achieving this range from a simple brush to expensive precision machinery in the electronics industry. Limiting coating area is crucial in some applications, such as printing.

"Roll-to-roll" or "web-based" coating is the process of applying a thin film of functional material to a substrate on a roll, such as paper, fabric, film, foil, or sheet stock. This continuous process is highly efficient for producing large volumes of coated materials, which are essential in various industries including printing, packaging, and electronics. The technology allows for consistent high-quality application of the coating material over large surface areas, enhancing productivity and uniformity.[6]

  1. ^ Carroll, Gregory T.; Turro, Nicholas J.; Mammana, Angela; Koberstein, Jeffrey T. (2017). "Photochemical Immobilization of Polymers on a Surface: Controlling Film Thickness and Wettability". Photochemistry and Photobiology. 93 (5): 1165–1169. doi:10.1111/php.12751. ISSN 0031-8655. PMID 28295380. S2CID 32105803.
  2. ^ Howarth, G A; Manock, H L (July 1997). "Water-borne polyurethane dispersions and their use in functional coatings". Surface Coatings International. 80 (7): 324–328. doi:10.1007/bf02692680. ISSN 1356-0751. S2CID 137433262.
  3. ^ Howarth G.A "Synthesis of a legislation compliant corrosion protection coating system based on urethane, oxazolidine and waterborne epoxy technology" Master of Science Thesis April 1997 Imperial College London
  4. ^ Wu, Kunjie; Li, Hongwei; Li, Liqiang; Zhang, Suna; Chen, Xiaosong; Xu, Zeyang; Zhang, Xi; Hu, Wenping; Chi, Lifeng; Gao, Xike; Meng, Yancheng (2016-06-28). "Controlled Growth of Ultrathin Film of Organic Semiconductors by Balancing the Competitive Processes in Dip-Coating for Organic Transistors". Langmuir. 32 (25): 6246–6254. doi:10.1021/acs.langmuir.6b01083. ISSN 0743-7463. PMID 27267545.
  5. ^ Campoy-Quiles, M.; Schmidt, M.; Nassyrov, D.; Peña, O.; Goñi, A. R.; Alonso, M. I.; Garriga, M. (2011-02-28). "Real-time studies during coating and post-deposition annealing in organic semiconductors". Thin Solid Films. 5th International Conference on Spectroscopic Ellipsometry (ICSE-V). 519 (9): 2678–2681. Bibcode:2011TSF...519.2678C. doi:10.1016/j.tsf.2010.12.228. ISSN 0040-6090.
  6. ^ Granqvist, Claes G.; Bayrak Pehlivan, İlknur; Niklasson, Gunnar A. (2018-02-25). "Electrochromics on a roll: Web-coating and lamination for smart windows". Surface and Coatings Technology. Society of Vacuum Coaters Annual Technical Conference 2017. 336: 133–138. doi:10.1016/j.surfcoat.2017.08.006. ISSN 0257-8972. S2CID 136248754.