FAQ Gold Plating
There is a great deal of confusion regarding the basics of gold plating and its relationship to thickness, color, and durability relative to real world and industrial standards. Here are some frequently asked questions that will help provide a basic understanding of gold plating principles.
We also invite you to review our related technical papers on gold plating.
The Gold Plating Primer
What is the difference between gold plating and gold filled (also called gold overlay)?
The most important difference is layer thickness. Items designated as “gold filled” can be up to 200 times thicker than the heaviest gold electroplating available today! Gold filled items are created by using heat and pressure to permanently fuse a layer of karat gold over a less costly base metal design. The minimum layer of gold must equal 1/20th of the total weight of the finished item.
The surface layer of karat gold is usually 10kt, 12kt, or 14kt. As an example, an item marked as “1/20 12k GF” would mean that 1/20th of its total weight must be 12 karat gold. One disadvantage for gold-filled items (i.e. watches) is that once the layer of gold wears through to the base metal, it will need to be resurfaced and replated to prevent discoloration. Gold-filled processes are still being utilized to produce fine watches, writing instruments, and assorted jewelry items. Gold electroplating, especially with advent of super hard plating materials, are widely used on designs which have intricate or complex shapes.
What is rolled gold plate?
Rolled gold plate is the same as “gold filled” except that the quantity of karat gold is less than 1/20th of the total weight of the finished metal item. It must be identified with a fraction mark indicating the quantity of gold. A typical legal marking might then appear as “1/40 12k R.G.P.”
What is gold “gilding”
Gilding involves the application of a gold coating onto a surface without the use of an electric current. Known as one of the most ancient of metal techniques, it involves the special combination of powdered gold and mercury blended into a paste-like amalgam. The mix is carefully applied to the designated surface area. The object is then heated, allowing the mercury to “boil off” leaving the gold layer deposit. It would then be burnished to the desired finish. Large surface areas could be covered in a relatively heavy layer of fine gold. It is also a process that is not utilized much today in the U.S. due to the unacceptable health risks from exposure to mercury. It is however used in some limited fashion for metal restoration projects where electroplating is not suitable.
What does Vermeil gold mean?
Pronounced ver-MAY, Vermeil gold is the official industry designation for a heavy gold electroplating over a base sterling silver material. A minimum thickness of 100 millionths of an inch or 2.5 microns of gold must be deposited before it can be marked or sold as Vermeil.
How is the thickness of gold plating measured?
The thickness for gold coatings and platings are often expressed in millionths of an inch, microinches, or microns. The table below will help provide a basic translation between these units of measurements.
To translate all this into real world plating thicknesses and their relationship to U.S. Gov. F.T.C. regulations, the following table expressed in microns is provided as a point of reference. We will be happy to help you select the most appropriate thickness of electroplated gold for your metal item.
gold flash – 10 kt gold with a minimum thickness of .175 microns.
gold electroplate – 14 kt or higher gold layer with a minimum thickness of .175 microns.
gold plate – 14kt or higher gold layer with a minimum thickness of .5 microns.
heavy gold plate – 14kt or higher gold layer with a minimum thickness of 2.5 microns.
vermeil – 14kt or higher gold layer over sterling silver with a minimum thickness of 2.5 microns.
For more detailed information on measuring goldplating thicknesses refer to article: “Measuring Layer Thickness on Gold Plated Objects”
Typically how long can I expect a gold plating to last on my jewelry item or object?
As a rule the thicker the plating, the longer it will last. If you have an item that is subject to high wear or abrasion we recommend a minimum thickness of at least 1.0 microns of electroplated gold. For items such as watches or writing instruments, we have plated thicknesses of up to 7.0 microns of gold. In most cases, this would exceed the original manufacturers specifications for lifetime durability. When done properly, and with normal usage, gold electroplated finishes can last literally for decades before replating is required!
How does Metal Arts Specialties measure gold plating thickness?
For applications where plating thickness is critical we periodically measure plated layers using a process called ” x-ray fluorescence”. This non-destructive method is very precise for measuring the actual metal deposition on an object after electroplating.
How are you able to achieve different shades and colours of gold plated finishes?
Gold plating baths are first modified by adding other metal alloys to the mixture. The addition of copper will enable us to electroplate gold with a “rose” colour. Alloys of silver will create plated gold that has a green hue to its colour. By modifying the bath temperature, different tints of these colours can be achieved.
Can more than one colour of gold plating be plated in the same piece?
Yes, this is called selective plating. Designated areas of the metal object can be plated with yellow, rose and green gold deposits. It also is used for selectively restoring gold plating on metal objects when traditional plating is not suitable due to the fragility of the piece.
Will the final finish of an object influence the tint and color perception after gold plating?
Yes definitely. The perceived gold colour is influenced by brightness of the surface finish. A matte finish will appear paler in colour. A shinier surface will always appear darker in colour. Bead blast or sand blast finishes will appear medium pale in colour when compared to shiny finishes. If colour matching is critical, we can provide (on a limited basis) plated samples that will help you select the correct finish for your item.
This article copyright Metal Arts Specialties. All rights reserved. This material may not be duplicated or copied without expressed written permission. Thank you.
Metal Arts Specialties
- +1 (248) 821-3450