This foil made from 24K real gold has been specially developed for a Koriaan technique called Keumbu or Keum boo. Processing a layer of gold on silver with gold foil.
Multiple layers can be applied for a deeper color and small bumps can be updated in this way.
Cut the shape you want between a piece of folded paper. Given the fragility, you have less chance of cracks. You can also use paper punches.
Keumboo or keumbu already take place in a large temperature range. Already from + -340°C, this makes it possible to apply keumboo at different temperatures. However, the ideal temperature to start with is around 400-450°C. At this temperature, the gold starts to stick to the silver.
The fine gold and fine silver exchange their molecules, so that the gold attaches itself naturally to the silver under light pressure.
Sterling silver will have to be heated several times (to grayish brown) and must be pickled to remove the copper from the top layer. This creates a layer of fine silver that can be worked on. If the silver is no longer discolored during heating, you are ready to get started.
Keum-boo on a hob:
Place a plate of metal on the hob to bring it up to temperature. Place the shape gold foil on your silver and possibly "stick" it with some spit so that it does not blow away. Place the workpiece on the metal plate. Hold the workpiece in place with tweezers and take your agate pen to lightly rub the gold from the center outwards. Be careful not to let your agate pen get too hot, because then the gold will stick to your agate pen. So a second agate pen is not a luxury so you can switch between times. If the gold is in place, remove your workpiece, the gold is heavier than the silver and slowly sinks into the silver. You can use this to add multiple color accents with it.
You can also use a brass brush to press on the foil, this is especially useful if there is a deeper structure that needs to be "filled".
Keum-boo with the kiln:
Can be used on a piece of silver that has already been baked. After the gold foil has been applied it has to be in the fire oven at 800 ° C for about 2 minutes to fuse with the silver. Wait until the oven indicates 800 ° C and after 2 minutes remove the piece and place it on a safe work surface, hold it in place with tweezers, immediately rub the hot surface with the agate polishing pen, start in the middle and push the gold foil firmly on the silver. Because of this the gold attaches to the silver. Repeat the process for large pieces or if the edges are still loose and the piece has cooled too much.
Note that if the piece is left in the oven for too long, the color may become weaker because the gold sinks into the silver because it is heavier than silver.
Gold leaf vs gold foil
Gold foil is not the same as gold leaf, gold foil is much thicker and more manageable than gold leaf.
Gold foil consists of 24K gold and with scissors you cut the desired amount. A paper punch can also be used, then place the gold sheet between two sheets of paper and punch out the shape. You can use a glue stick (prit) to hold the gold in place when it enters the oven.
3.5 x 5cm x 0.013mm thick (13 microns)