Updated: Jan 29, 2018
A small tutorial on the process of Keum-boo and a recipe for Gintilly
This week I am working on collections for my March 3, 2018 artist reception which will be at the lovely Ariodante Gallery on Julia Street in New Orleans. I am creating several collections inspired by that beautiful city and one of those collections will be accented with 24 karat gold by using the Keum-boo technique. I will also be offering a recipe for a Gintilly Fizz, my rendition of the wonderful Gintilly Shakedown, my favorite cocktail from my favorite seafood place in NOLA, Peche.
Keum-boo, "attached gold" is a Korean method of applying high karat gold to silver. Simply stated and simple learn. It is a fairly inexpensive way to add that glimmer of gold to your jewelry pieces. I love the look of high karat gold against a highly oxidized piece of jewelry.
High karat gold and pure silver have a very similar molecular makeup. When silver is heated to a certain temperature and a thin layer of gold is applied with pressure, a permanent diffusion bond is created between the gold and silvers molecules, thus attaching the gold to silver. Attached gold.
The tools for applying the gold are pretty straightforward: some sort of a hotplate or trinket kiln with brass plate adaptors, a variety of metal or agate burnishers, long tweezers, small paintbrushes, heatproof gloves, gold foil, exacto knife, cutting board, tracing paper or thin tissue paper and a heatproof surface on which to work.
Keum-boo should be worked after all soldering is completed and before any stones are set or patina is applied. That being said, I have soldered after my Kuem-boo is finished and have had no issues with the gold sinking into the silver at soldering temperatures. I work in sterling silver and if you do as well, then your first step will be to raise a layer of pure silver onto your jewelry piece. This process is called "depletion guilding". To depletion guild, you need to torch your finished piece of sterling jewelry until a black oxide layer forms. Then, quench and pickle your piece. As you take it out of the pickle you will have that familiar frosty white look of just out of the pickle-pot sterling. The pickle has eaten away the oxide layer of copper and what remains is a thin layer of pure silver. Repeat this process about 6 to 7 times. You will notice that during each successive torching, the sterling will create less of a black oxide layer, the piece looks white under the torch prior to the pickle bath. This is what you are looking for. This means that your silver layer is sufficient enough to apply the gold sheet. You may leave this layer as is or take a soapy wet brass brush to it. Polishing with an abrasive compound will simply remove the silver layer. As a note, depletion guilding is also helpful to cover fire scale, if you are unable to remove it in other ways.
The set up I use for heating the silver is a Ultralite granulation kiln with keum-boo brass plates. My setup was purchased from Rio Grande Supply for around $125. You may use a hotplate, that is the most inexpensive way to go, and works fine, but you will need to work with heatproof gloves and I find it awkward to do so. I chose the kiln as you can also use it for firing metal clay, firing enamel and doing granulation. The exterior of the kiln heats up less than a hotplate and there is a opening which directs heat away from your face and hands. I find when I use the kiln, I do not need to use heatproof gloves. The kiln with the brass plate heats to a perfect 700 degrees, which is the exact temperature you need for the process. I didn't bother with the additional control plug which can be purchased at additional cost.
The gold sheet you use is thicker than gold leaf and is available at jewelry supply companies as Kuem-boo foil. At the time of writing, a 3 x 3 sheet of gold foil is about $85. This may seem expensive, but a little goes a long way.
I start to heat my kiln, brass plate in place, on my heatproof surface and arrange all my tools nearby. You will need to be able to put your really hot sterling onto some heatproof surface when off the kiln so be prepared! A few porcelain tiles should do the trick or use your steel bench block. I have a wood chopstick near my kiln, and when the the end of the chop stick burns when placed on the brass plate, I know I am at temperature and I place my sterling piece onto the hot brass plate atop my kiln. Sterling conducts heat well and if your piece is small it should be at temp in just three to 5 minutes. While your piece is heating, cut your gold foil.
Thin gold foil is a delicate beast, so it is best to cut it between sheets of tracing or tissue paper, using either an exacto knife or a crafting paper punch. Be careful not to get hand oils on the sheet as this may hinder adhesion. Cut the number of pieces you need for your project. To start the diffusion bonding process steady your piece as it sits on the brass plate using either a burnisher or long tweezer. Using either another tweezer or a small wet paintbrush, pick up your first piece of foil and place it on the sterling. A gentle tap with a burnisher onto the gold should immediately hold the gold to the silver. Then continue to burnish until all air bubbles are gone and the edges of the gold look sealed. You do not need to overdo this, it does not take a lot of pressure, but the whole piece of foil and edges should be burnished. If your burnisher get too warm, which will happen, trade off for another, and let the first one cool. This way you don't gold plate your burnisher. Continue adding pieces until your design is complete.
Remove your piece from the kiln, cool, and if there is any darkening of the sterling, place in a quick pickle bath, rinse and burnish the whole piece with a soapy, wet brass brush. I like to apply a liver of sulfur patina to my pieces and now is the time to do that. I find using Silverblack will patina the gold in addition to the silver, which I don't want, so I don't use that product for Keum-boo. Set your stones and you're all done.
Yes, the first time I did this I was nervous. I burnished gold onto the hotplate, attached gold where I didn't want it on the piece I was working, and had pieces of foil pop off right as I was going after it with the burnisher. I have never burned my hands or ruined a piece and each time I engage in this process, it gets a little easier.
Gintilly Fizz for 2, or just 1 if it has been a really long day in the studio
Ginger Simple Syrup (see gin and jewelry post) #gingersimplesyrup
Thyme Syrup (see below)
Wash and cut into chunks one cucumber and place in a glass container and into that pour contents of one bottle, (any size) gin. Let sit for at least three hours, refrigerate.
In the alternative use crazy expensive Hendricks, and if you use Hendricks, please come to my opening at the gallery, I have some jewelry to show you.
Pour a two to one ratio of gin to fresh squeezed lemon juice (So, two large shaker caps of gin, one of lemon) into a tall glass.
Add about two tablespoons of ginger syrup, 1 tablespoon thyme syrup, add ice and top with prosecco.
1 cup sugar
1 1/2 cup sugar
1/4 cup fresh thyme sprigs
Combine all ingredients over medium heat, bring to simmer and simmer for 20 minutes. Allow to cool and strain through a fine mesh strainer into clean jar. Refrigerate.