Episode9: Accessories (Decorative Plating)

When accessories are made only using noble metals, they become extremely expensive or heavy, and may become clumsy to use. “Plating” not only solves these problems but also adds value to the accessory. In addition, “plating” has become essential for musical instruments, too.

What is decorative plating?

Advantages of noble metal plating

Decorative plating is used for the decorative portions of accessories and furniture. There are many types of decorative plating but the most common is the noble metal plating of gold, silver, etc. I would like to summarize the main reasons as follows:

  • Attractive appearance:Beautiful metal colors
  • Luxurious feel:“Plating” using expensive noble metals such as gold, silver, platinum, etc.
  • Rust prevention:To prevent corrosion by sweat, etc.
  • Reduced weight:Much more lightweight than a material made of only noble metal and easy to wear.
  • Cost reduction:Inexpensive compared to noble metals themselves.
  • Antibacterial effects:Antibacterial action of metal.
  • Antiallergic effects:Noble metals are not too reactive.

Features of “plating” used for accessories

Let us look at the features of typical “plating” used for decorative purposes such as accessories.

Types of platingFeatures
Gold platingProvides a luxurious feel and unique color tone. Non-allergenic and suited for accessories.
Silver platingMirror-like visual effects enjoy high popularity; however, the color may sometimes dull after long-term use.
Platinum platingBeautiful appearance, called white gold, is liked by everyone, and non-allergenic.
Nickel platingUsed for several things and as the first plating layer for other metal plating, but is allergic.
Chromium platingProvides a unique surface and excellent durability against heat, corrosion, etc.
Rhodium platingUse as a thin film on silver plating can prevent silver discoloration and achieve luster, strength, etc.
Palladium platingUsed as first plating layer for gold plating in place of nickel. Being silver white, it is also used as a substitute for rhodium plating.
Titanium platingProvides a hard surface and is non-allergenic.

Antiallergenic effects by “plating”

Allergies caused by metals are triggered by the ionization of metals released by contact with sweat, etc. and entry into the body.

The ionization of released metals relates to the “ionization tendency” discussed in Episode 4. That is, because “a metal that can easily be ionized is a base metal,” base metals have a high probability of causing allergy. In the case of accessories, allergy problems related to nickel plating, which is easy to process and is comparatively inexpensive, are frequently seen.

Conversely, because “a noble metal is a metal difficult to be ionized,” allergy problems are considered less frequent in noble metals. Noble metals are popularly used for accessories that directly come in contact with skin from the viewpoint of beautiful appearance and allergy prevention.

*Metallic allergy is related to a person’s constitution. Even noble metals may cause allergies; hence, care must be taken.

Relationship between “plating” and musical instruments

Does plating affect the tone quality?

Musical instruments also have a close connection with “plating.” In particular, for trumpets, saxophones, flutes, clarinets, and other brass instruments, surface treatment including “plating” plays an important role. Some instruments have their main bodies “plated” (surface treated) and some have only their keys (portions switching sounds by pressing by fingers) “plated.” Musical instruments are “plated” (surface treated) primarily for the purpose of providing visual classiness and protecting from corrosion but it is said that the types of “plating” (surface treatment) and coating film thickness also affect the tone quality(*).

For “plating” of musical instruments, gold and silver plating are popularly used, which provide a visually luxurious feel and excel in rust prevention, and nickel plating, etc. are used depending on the musical instrument.

*In brass instruments, vibrations generated in the mouthpiece and the lead become the sound source. It is, therefore, said that the surface coating film thickness and ingredients of the coating film have a big effect on the vibrations and change the sound quality.

World of surface treatment

Things around us are provided with some type of “surface treatment.” “Plating” is one of the principal methods. The figure below summarizes the types and characteristics of the surface treatment.

As I told you in Episode 1, the types of “plating” can be divided into a wet-plating process and a dry-plating process, and the two plating processes can be further subdivided into electroplating and electroless plating, and physical vapor deposition and chemical vapor deposition, respectively.

The “hot dipping method,” a type of “plating”, is generally called “hot-dip galvanization.” Zinc plating is typical and is frequently used for the purpose of rust prevention of large metal products, and is inexpensive.
“Thermal spraying” is a process similar to “plating,” as a process for creating a metal coating film on a surface. Thermal spraying forms a metal coating film by spraying metals melted at high temperature onto the substance.
Processes for coating materials other than metals on the surface include “coating,” “lapping,” “printing,” and others.
“Polishing” is a method of surface treatment that is not coating but a process of material removal by scraping.

A profound world of surface treatment and “plating”

In this Episode, I discussed plating with the primary emphasis placed on decorative plating, and introduced that “plating” is also used for musical instruments. At the same time, you saw a part of the world of surface treatment in which “plating” is included. Upon performing a thorough investigation of surface treatment including “plating,” we learnt that surface treatment relates not only to the “surface,” such as beautiful appearance and luxurious feel, but also to the “profound world” as it exerts an effect on the sound quality in the case of musical instruments.

Surface treatment is the treatment that is provided to all things in a sense, and “plating,” which is a type of surface treatment, plays a significant role in various things. Things around us are surface-treated. If we see familiar things around us and ask “What kind of surface treatment is provided?” we may be able to find out its different aspects.