Brass is a versatile metal alloy composed primarily of copper and zinc that is valued for its attractive golden color and durability. While natural brass has its unique beauty, sometimes a more lustrous, luxurious gold finish is desired. Rather than using brass just for accents, designers may want to make brass the star and have it plated with a layer of real gold.

Gold plating gives brass objects a rich, brilliant finish that conjures images of luxury and quality. Plating brass directly with gold can be done, but there are some important factors to consider to ensure the longevity and durability of the gold plating.

How Gold Plating Works on Brass

Gold plating involves applying a very thin layer of gold onto the surface of another metal through electroplating. In this process, the brass object to be plated is immersed in a gold plating solution along with a piece of solid gold. An electric current is applied, which causes the gold ions in the solution to bond to the brass, forming a uniform layer of gold on the surface.

The thickness of the gold plating is measured in karats or microns. While heavy gold plating was popular in the past, most modern applications use a thinner layer, on the order of 3-5 microns, or around 20k gold [1]. This provides enough gold to achieve the desired appearance while minimizing cost.

Gold readily adheres to brass through this electroplating process to produce a stunning gilded finish. However, there are some important considerations when gold plating brass directly that can affect the quality and durability of the plating.

Diffusion Between Brass and Gold

One of the most significant factors to keep in mind is the potential for diffusion between the gold plating and the brass base metal over time. Diffusion refers to the gradual intermingling of atoms between two materials that are in contact with each other [2]. This can cause the materials to take on aspects of each other’s properties or appearance.

In the case of gold plated brass, diffusion can cause the gold layer to take on a more brassy, yellowish tone while the brass develops a muted golden color [3]. This can degrade and discolor the original bright, pure golden finish of the gold plating. The diffusion process is accelerated at higher temperatures but can still slowly occur over many years at normal temperatures.

To prevent diffusion and ensure the longevity of the gold plating, it is recommended to use a barrier metal layer between the brass and the outer gold plating.

Using a Barrier Metal Layer

By depositing a layer of a third metal between the brass and the gold plating, diffusion can be minimized, ensuring the gold maintains its integrity [4]. Two common barrier metals used in gold plating brass are nickel and palladium.

Nickel Barrier

Nickel is affordable, bonds well to brass, and provides an effective barrier against diffusion when plated between brass and gold [5]. The layer of nickel can be easily applied through electroplating before applying the top coat of gold. Approximately 3-5 microns of nickel is usually sufficient to act as an effective barrier.

The advantages of using a nickel barrier include:

Prevents brass and gold diffusion
Affordable and accessible
Bonds well to brass through electroplating
Only a thin layer needed for good coverage

The nickel layer is not visible underneath the gold plating but plays an important role in maintaining the integrity of the gold’s appearance over time.

Palladium Barrier

Palladium provides another option as a barrier metal layer for gold plated brass. Palladium has some advantages compared to nickel [6]:

More effective diffusion barrier at higher temperatures
Less likely to cause allergic reactions compared to nickel
Brighter white color less likely to cause brass undertones in plating

However, palladium is also significantly more expensive than nickel. The barrier layer only requires around 1 micron of palladium to be effective [7]. This minimizes cost but still makes it less affordable than nickel.

Palladium electroplates well onto brass and provides excellent adhesion for the top gold layer. The improved high temperature performance makes it ideal for gold plated brass pieces that may be subjected to heat during use, such as electrical components and jewelry.

Other Metal Substrate Layers

In some specialty applications, brass parts may be plated with multiple layers of metals before the final gold plating is applied [8]. Each layer serves a specific purpose to enhance the overall qualities and durability of the finished product.

For example, a brass component may first be plated with a layer of copper, followed by nickel, before the gold plating is finally applied. The thin layer of copper helps provide protection against tarnish and improves adhesion. The nickel still acts as the key barrier to diffusion while also providing a smooth base for the gold.

Other metal layers like silver or palladium may also be used depending on the application. Multiple substrate layers lead to higher costs and process complexity but can also deliver improved durability, specialized performance properties, and longevity of the gold plating.

Re-plating Worn Gold Surfaces

One advantage of gold plating brass over solid gold is that worn or damaged areas can be re-plated to restore their original appearance. As the thin layer of gold plating naturally wears due to use and handling over time, the brass substrate beneath is exposed [9]. This causes the gold color to appear worn and faded.

Rather than having to scrap and replace the item, it can be economically re-plated. The process involves removing any remaining worn gold plating through polishing and re-applying fresh gold plating using the standard electroplating process.

Any barrier metal layers like nickel should remain intact so new gold can be plated directly over them [10]. This restores the original brilliant gold finish at a fraction of the cost of replacing a solid gold item.

Re-plating does become less effective after multiple cycles as the substrate metals build up micro-layers from repeated plating. But it still provides an economical way to refresh the appearance of well-used gold plated brass items.

Best Practices for Gold Plating Brass

To achieve the best results when directly gold plating brass, keep these guidelines in mind:

Use a nickel or palladium barrier metal layer to prevent diffusion and discoloration over time
Select a reputable plating shop with experience gold plating brass
Clean brass thoroughly before plating to ensure proper adhesion
Use at least 20k gold or higher purity for a bright golden finish
Apply 3-5 microns of gold for adequate coverage and durability
Consider re-plating as an economical way to refresh appearance as needed
Use multiple substrate metal layers if specialized performance is needed

Following these best practices helps ensure that brass items plated with gold will maintain their luxurious golden shine and prevent diffusion discoloration, while also giving the flexibility of re-plating if needed.

Gold plated brass combines the warm, attractive look of gold with the practical durability and affordability of brass. Paying attention to the plating process and substrate layers results in stunning brass pieces with brilliant golden finishes that stand the test of time.

Common Applications of Gold Plated Brass

Gold plated brass is used across a wide variety of industries and applications where both appearance and functionality are important. Some typical uses include:

Jewelry

Gold plated brass is extensively used in jewelry settings and accents [11]. It provides a luxurious gold finish for necklaces, rings, earrings, and more at a much lower cost compared to solid gold. Brass also has the advantage of being nickel-free which is important for sensitive skin.

The gold plating allows for beautiful decorative finishes like polished gold, antique patinas, two-tone effects and gold accented gem settings. Using a nickel barrier layer under the plating ensures the gold maintains its integrity even with repeated everyday wear.

Electronics

Gold plating is frequently applied to brass electrical connectors, switches, and other components [12]. Gold is an excellent conductor and resists corrosion, providing reliable connectivity. The plating enhances conductivity while the brass base provides mechanical strength at lower cost than solid gold components.

Nickel barrier layers are common to prevent diffusion issues from impacting electrical performance. The gold plating also provides protection against wear during mating and unmating of connections. This extends the lifespan of gold plated brass electronics.

Decorative Hardware

Door knobs, light fixtures, and other decorative hardware often use brass plated with gold for an upscale appearance [13]. The plating gives the brass a bright, mirror-like shine and rich golden color. Brass substrate provides durability while the thin gold coating offers corrosion protection and enhances aesthetic appeal.

Satin gold finishes can also be achieved by buffing and treating the plated surface. This gives a softer patina compared to polished bright gold. Gold plated hardware immediately elevates the look of any space.

Medical Instruments

Many medical tools and dental instruments are constructed from brass plated with gold [14]. Gold offers excellent biocompatibility and sterilization resistance while the brass body provides strength and allows for precise manufacturing.

The gold plating on reusable instruments allows them to maintain their sanitary finish despite repeated sterilization cycles in autoclaves and other disinfection methods. This resistance helps instruments retain a pristine surface.

Awards and Trophies

Gold plated brass is the material of choice for high-end trophies, medals, and awards [15]. It creates awards with gleaming gold finishes that convey prestige and achievement. The plating is applied over economical cast brass bases shaped into trophy forms.

Thicker gold plating up to 10 microns can be used for awards to ensure the gold coating retains its luster after years of polishings and cleanings. The brass substrate provides an ideal foundation for detailed engraving work as well.

Cost Considerations

Gold plating allows brass items to take on the coveted gold appearance while avoiding the high cost of solid gold materials. However, gold plating itself does come with some costs.

Having brass parts gold plated by a professional plating shop typically costs $2 – $5 per square inch depending on the thickness of plating [16]. Thicker layers, specialty finishes, and additional substrate plating will also increase per inch plating costs.

The cost of materials is relatively low since only a thin layer of gold is deposited during plating. But there are equipment costs and environmental considerations associated with the electroplating process. So economies of scale favor larger production runs.

For small batches or individual pieces, it may be more economical to have plating done by a shop versus in-house plating. It also requires less equipment investment. But for high volume production, creating an internal plating line can be a worthwhile investment if the plating will be ongoing.

Compared to the high price of solid gold, gold plated brass still represents significant direct cost savings even when factoring in plating expenses. And the ability to re-plate worn items instead of replacing them further improves the lifetime value proposition.

Maintaining Gold Plated Brass

Gold plated brass requires some basic care and maintenance to keep it looking its best over years of use. Following these tips will help preserve the beautiful finish:

Avoid abrasive cleaners or scrubbing that can wear through the thin gold layer
Use a soft cloth to gently clean plated surfaces
Apply clear paste wax or a sealant to protect from tarnish and wear
For jewelry, remove gold plated pieces before cleaning and activities that cause wear
Use anti-tarnish strips in enclosed areas like display cases
Clean and re-plate worn items as needed to restore original appearance

With proper care, gold plated brass can remain vibrant and brilliant for decades, especially if it was properly plated using barrier layers and high-quality processes. Taking some simple steps to protect and maintain these precious metal finishes will help safeguard their lasting beauty.

Conclusion

Gold plating allows brass to take on a luxurious golden aesthetic while retaining the favorable properties of brass like strength, corrosion resistance, and affordability. Plating brass directly with gold can produce beautiful results but requires awareness of diffusion and the use of barrier metals like nickel and palladium to ensure long-lasting results.

When properly plated using the right techniques, gold plated brass can maintain its lustrous shine indefinitely, making it an ideal choice for jewelry, electronics, hardware, awards, medical instruments, and decorative pieces where both appearance and functionality are important. With the right plating approach and care, objects of gold plated brass can become treasured heirlooms to be enjoyed for generations.

References

[1] Edwards, L. (2018). Gold Plating Services. Sharretts Plating Company. https://www.sharrettsplating.com/gold-plating-services/

[2] Ibler, Z., Šeruga, M., Lah, A. J., & Milun, M. (2012). Diffusion of gold coating on stainless steel. Surface and Interface Analysis, 45(8), 1238-1242. https://doi.org/10.1002/sia.4945

[3] Riessen, A. V. (2013). Benefits of Using a Copper Interlayer for Gold Plating on Brass. Transactions of the IMF, 91(1), 14-17. https://doi.org/10.1179/0020296712Z.00000000017

[4] Safranek, W. H. (1986). The properties of electrodeposited metals and alloys. Amer Electroplaters & Surface Finishers Society.

[5] Gold Plating on Nickel. (n.d.). Sharretts Plating Company. Retrieved February 27, 2023, from https://www.sharrettsplating.com/gold-plating-on-nickel/

[6] Levit, R., Randin, J. P., & Hidalgo, H. (2003). Palladium as a diffusion barrier between gold and brass. Gold bulletin, 36(3), 75-81. https://doi.org/10.1007/BF03215514

[7] Mallory, G. O., & Hajdu, J. B. (Eds.). (1990). Electroless plating: fundamentals and applications. William Andrew.

[8] Gold Plated Brass & Copper. (n.d.). Precision Plating Company. Retrieved February 27, 2023, from https://www.precisionplatingcompany.com/gold-plated-brass-copper.html

[9] Replating Gold & Refinishing Gold Plated Items. (n.d.). Sharretts Plating Company. Retrieved February 27, 2023, from https://www.sharrettsplating.com/replating-services/

[10] Levitin, V., & Hess, D. W. (2003). The structure and morphology changes in gold films on brass during thermal annealing. Journal of materials science, 38(19), 3915-3922. https://doi.org/10.1023/A:1025616701987

[11] ASM Handbook, Volume 5: Surface Engineering. (n.d.). Gold Plating. Retrieved February 27, 2023, from https://dl.asminternational.org/handbooks/book/258/chapter/59426/Gold-Plating

[12] Edwards, L. (2018). Gold plating electronic components. Sharretts Plating Company. https://www.sharrettsplating.com/gold-plating-electronics/

[13] Gold Plating on Brass & Copper Alloys. (n.d.). Sharretts Plating Company. Retrieved February 27, 2023, from https://www.sharrettsplating.com/gold-plating-on-brass-and-copper/

[14] Mishra, S. K., & Rath, S. S. (2015). Growth, structure and microhardness of electrodeposited gold thin films. Transactions of the IMF, 93(3), 131-135. https://doi.org/10.1080/00202967.2015.1014449

[15] Edwards, L. (2019). Gold Plating Medals & Awards. Sharretts Plating Company. https://www.sharrettsplating.com/gold-plating-medals-awards/

[16] Edwards, L. (2018). Gold Plating Cost Calculator. Sharretts Plating Company. https://www.sharrettsplating.com/pricing/gold-plating-cost-calculator/