Difference Between Coating and Plating

The key difference between coating and plating is that coating can be done on both conductive and non-conductive surfaces, whereas plating can be done on conductive surfaces.

Coating and plating are techniques used to cover surfaces of objects with a substance. We call this object the “substrate”. The purpose of this covering can be decorative, functional or both. For example, surface covering is sometimes important for a better appearance of the object and may also prevent the surface of the object from corrosion.

CONTENTS

1. Overview and Key Difference
2. What is Coating 
3. What is Plating
4. Side by Side Comparison – Coating vs Plating in Tabular Form
5. Summary

What is Coating?

Coating is covering the surface of an object. The object that is being coated is usually referred to as the substrate. Coating is important for decorative purposes, functional purposes or for both. For example, paints and lacquers are important in protecting the surface of a substrate and also for decorative purpose. The functional properties of coating include adhesion, wettability, corrosion resistance, wear resistance, etc. Coating can completely cover the object or only some parts of the object.

One of the main facts about coating is the application of the coating at a controlled thickness. Most of the times, we apply only a thin film of coating such as paper, fabric, film, foil, and sheet stock. Moreover, the coating material can be a liquid, solid, or a gaseous substance.

There are both destructive and non-destructive methods that are important in analyzing a coating. For example, the microscopic analysis of a mounted cross-section of the coating and substrate is a destructive method, while ultrasonic thickness measurement is a non-destructive method.

What is Plating?

Plating is a type of coating in which a metal is deposited on a conductive surface. This technique was used by humans since ancient times, and it is useful in modern technology as well. The purpose of plating can be decorative, corrosion inhibition, improving solderability, hardening, reduction of friction, alter conductivity, improving the IR reflectivity, radiation shielding, etc. For example, we use plating in the jewellery industry to get a gold or silver finish.

There are different methods of plating, such as electroplating, vapour deposition, sputter deposition, etc. Electroplating method uses an ionic metal that is supplied with electrons to form a non-ionic coating on a substrate. In electroless plating methods, there are several simultaneous reactions in an aqueous solution without the use of external power supply. In addition to that, there are some specific plating techniques that are named according to the metal that is used for the covering; for example, gold plating, silver plating, chrome plating, zinc plating, rhodium plating, tin plating, etc.

What is the Difference Between Coating and Plating?

Coating and plating are techniques of surface covering. The key difference between coating and plating is that coating can be done on both conductive and non-conductive surfaces, whereas plating can be done on conductive surfaces. Furthermore, a coating can be done either using simple methods such as brushes or using expensive machinery while plating involves the application of a metal on a surface using an external electric current or using some simultaneous reactions.

The following table summarizes the differences between coating and plating.

Summary – Coating vs Plating

Coating and plating are techniques of surface covering. The key difference between coating and plating is that coating can be done on both conductive and non-conductive surfaces, whereas plating can be done on conductive surfaces.

Reference:

1. “Plating.” Wikipedia, Wikimedia Foundation, 7 July 2020, Available here.

Image Courtesy:

1. “2 gold glass bottles and green glass bottle” (CC0) via PeakPx
2. “Copper electroplating principle (multilingual)” By Torsten Henning (Multilingual Perhelion) – Own work (Public Domain) via Commons Wikimedia