Introduction: Keum-Boo (Attaching Gold Foil to Sterling Silver)

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Keum-Boo “attached gold” is an ancient jewelry technique originating in Korea, which is used to attach gold foil to sterling silver. The bonding of gold and silver are achieved through pressure and heat. During this fusion-bonding atoms are exchanged leaving us with a collision of two metals as one, and one greater valued and aesthetically pleasing piece of adornment (lets hope).

List of Materials:

1. Gold Foil

Vendor Item # Price

Rio Grande 623013 $98.74

Otto Frei 143.485 $81.00

2. Cast, Sheet or PMC STERLING SILVER object

3. Hot Plate- must be able to achieve 500-700 degrees (recommended over using a stove top)

Vendor Item # Price

Target 10155042 $16.99

4. Burnishers (three is preferred one to hold the Keum-boo, one to burnish and an extra to let one cool) while you can use a regular burnishing tool I have seen better results using the Agate burnishers.

Vendor Item # Price

Rio Grande (Ball Tip, Sword Tip, Knife Tip) 111361,111363, 11362 $10.95 Each

Otto Frei (Pointed Tip, Knife Shape) 118.073,118.074 $9.95 Each

5. Steel Block: Not required but very helpful

Vendor Item # Price

Otto Frei 112.325 $15.20

Rio Grande 112560 $14.00

6. Tracing Paper: Required if you want to cut into special shapes. Any tracing paper.

Vendor Item # Price

Dick Blick 10631-1023 $2.89

7. Scissors: Required if you want to cut gold foil into special shapes

8.Tweezers: YOU ABSOLUTLY NEED THESE! Even medical tweezers will work.

Vendor Item # Price

Otto Frei 157.0738 $ 2.75

Rio Grande 115018 $2.75

9. Thin twig, chop stick or piece of scrap wood

Step 1: Step 1: Set Up

Keum-Boo should be a final finishing process to a piece much like setting a stone. Before you add your gold foil you will want to make sure you have finished soldering and cleaning up your piece entirely.

Once you have gathered all your materials give yourself sometime to think about what shape or pattern you want to create in your piece (your materials are an investment especially if its a piece you have worked long on or cast).

I chose a triangle for my sample piece (I wanted to make sure this worked before investing lots of time into my cutting techniques ext.) I highly recommend testing your hot plate and tools before trying on a final piece. For a sample piece you can cut any size or shape to start. I cut an approximate 1"x1" square out of my sterling silver sheet. You can buy sample squares pre-cut from Rio Grande or Otto Frei if you don't have a pair of metal shears for cutting metal. For your gold foil Make sure to cut it using sharp scissors and NOT TOUCHING IT WITH YOUR FINGERS (the oils on your hands will contaminate the metal and not allow it to bond properly, this is where we use the tracing paper as an aid)! Once you have your pre-cut sterling silver object and pre cut piece of gold POWER YOUR HOT PLATE ON.

Step 2: Step 2:Fire It Up

My hot plate takes about 10 minutes to heat up to the proper temperature. To properly test your hot plate temperature you can gently roll the twig you collected from the back yard over the surface of the hot plate. Get a long enough twig so your fingers have room to roll the twig across the surface of the hot plate. Once the twig begins to smoke after you are rolling the twig this means your hot plate is ready to go!

Step 3: Step 3: Start to Heat It Up

Make sure you have your steel block next to your hot plate so you can set it on there as soon as your done. With your soldering tweezers take your piece of sterling silver and put it at the center of the hot plate. Wait about one minute, then place your foil on your sterling silver piece using the tweezers.

Step 4: Step 4: Start Burnishing

As soon as your foil is in the correct position begin to burnish! Using the agate burnisher with a curve apply pressure on the middle of the foiled piece while holding your sterling silver piece with another burnisher in the opposite hand (this will help keep it in place). I started from the middle and then worked my way towards the edges of the foil. Be very careful not to press to hard (you can scrape away or off gold foil that has not bonded yet). A minute in to burnishing I switch my burnishers for the third extra one to ensure they don’t get to hot on my gold foil. Depending on how large the piece is and how hot your hot plate is will determine how long you will need to burnish. I only needed to for about 3 minutes. You can tell your foil has bonded to your silver when it looks completely flush with the piece and no more marks are shown when you are burnishing.

Step 5: Step 5: Cool It Off

When your piece has completely bonded take your piece off the hot plate and place it on the steel block. Let leave till cool (the steak block helps absorb the heat) DO NOT QUINCH!!!

Step 6: Step 6: Finishing

Once your piece is cooled you may take it into your hand. A good way to test that you have bonded your metals is by a taking your fingernail and lightly scratching the surface from gold to silver (nothing should flake off or happen). I took scotch brite and 3m wheels on my surface to insure the metals were one, AND IT WORKED!
You can experiment with patinas, and different finishing tools once you are complete. I would recommend not using anything abrasive on the gold surface after it’s on there. It is such a thin amount of material that chances are some spots might shine through to silver sooner rather than later.

- Some Patinas will react to certain metals but not others. Use this to your advantage, but also do test samples on your materials before applying to your final piece. A good example of this and most frequently used patina is Liver of Sulfur. This will darken your sterling silver while not changing your gold.