Heard the name and want to put a face to it? What exactly is the Keum-boo gilding technique? Where did it come from and why is it now so popular in the west?
All this and more today as we explore the origins of the Keum-boo gilding technique in Korea and beyond.
What is Keum-boo?
Keum-boo – also known as Geumbu, Kum-Boo, or Kum-bu – is an ancient gilding technique hailing from Korea that is used to apply thin sheets of gold (even gold foil) to silver. The phrase is actually Korean, literally meaning attached gold.
The Keum-boo technique involves depleting a surface of sterling silver to bring up a thin layer of fine silver, after which the thin gold foil is applied with heat and pressure to produce a permanent diffusion bond. This latter part of the process utilizes a form of mechanical gilding that has been deemed pretty darn advanced for its time.
Pure precious metals like gold and silver have remarkably similar atomic structures and it is thus that they have a good potential for bonding in this way. Heating such metals to temperatures between 260 and 370°C can increase the movement of the atoms between them. Applying pressure, then, can cause an electron exchange on the surface of the two metals, creating that all-important diffusion bond permanently.
Examples of this technique in both silver jewelry and gold jewelry have been observed from the second half of the first millennium B.C. and then from the early first millennium A.D.
From its birth in Korea, the technique has come to be used in many different cultures, including Chinese, Japanese, and, more generally, the west. Instead of just sticking to thin gold foils on a hot plate, the technique has since been used to bond pure gold to other metals like iron, copper, aluminum, gold alloys, white gold, palladium, and platinum.
Alternatively, foil made from gold alloys can be applied to silver and other metals by first using a process called depletion gilding to ready the surface of the foil for melding.
How to Look After Keum-boo Jewelry
Here are a few notions to follow if you want to make your Keum-boo jewelry last longer:
- Contrary to popular logic, wearing your Keim-boo jewelry regularly is actually a good thing. The natural oils in your skin help keep the sterling silver in this kind of jewelry shiny, slowing the process of tarnishing considerably.
- Make sure to remove any Keum-boo jewelry if you are showering, cleaning, or swimming (or any other related activities). Household cleaners and soap might contain chemicals or essential oils that harbor the possibility of doing some serious damage to the jewelry. Perspiration, chlorine, and even rubber can also accelerate this tarnishing process. So, if you intend to do any spring cleaning or swim in the pool, you would do your best to leave your jewelry aside
- Putting on your Keum-boo jewelry last can also help to ensure that it lasts longers. Hairspray, perfume, and other lotion or body products might contain the kind of corrosive chemicals mentioned above. Thus, it would be best if you put on your Keum-boo jewelry on last before you go out where you are intending to go so you can minimize the amount of time that the jewelry has to be in contact with these harmful chemicals.
Cleaning Keum-boo Jewelry
Even if optimally cared for, Keum-boo jewelery should still be cleaned fairly regularly. This can be done with mild soap, water, and a soft microfiber rag. Soap and water is amply suited to removing dirt while still remaining gentle with the jewelry.
If, for some reason, they are not enough, try making a paste with baking soda and water, using a soft toothbrush to scrub if necessary.
So, there you have it! Hopefully, you are now feeling a little more informed on the subject of Keum-boo. If you are a jeweler, why not give this a go yourself, albeit in a simplified form?
FAQs Keum-boo Gilding Technique
Gold leaf foil is actually perfectly suited for the Keum-boo gilding technique. The thickness means that you can get a great color on the jewelry without needing to overlay and repeat the process, unlike some other materials used for the very same purpose. Gold foil is better suited for the specific needs of Keum-boo, though you can easily use gold leaf for the same purpose, provided you also use a specifically designed adhesive for the job – water-based ones are better.
Keum-boo is about as permanent as any bonding gilding technique. Keum-boo – also know as Geumbu, Kum-Boo, and Kum-bu – is a Korean gilding technique whose etymology literally means ‘attached gold’. Thus, the wise amongst you will have realized that the technique essentially involves attaching gold to another metal. The original Korean method utilized this technique with silver, though it is often used with iron, copper, aluminum, gold alloys, white hold, palladium, and platinum nowadays, especially since this technique has migrated away from its Eurasian origins and has since become a staple of western gilding and jewelry in general.
The heat needed for Keum-boo will ideally be between 260 and 370°C. Pure precious metals like gold and silver – those that feature prominently in the original Keum-boo technique – have a remarkably similar atomic structure and, thus, have a great potential for bonding together. Heating the metals to the aforementioned requisite temperature causes an electron exchange between the two metals which creates a permanent diffusion bond. Remarkable, too, is the fact that this fusion bond occurs well below the soldering temperature for either of these metals alone.