Gold Granulation by Nao goldwork
| Greetings | Gold granulation technique |
Why is the "granulation technique" important?
(Point 1) Why is the granulation technique used to create gold products?
→ This is because the granulation technique makes it easy to
create products using 24-karat gold.
(Point 2) Why do I use only 24-karat gold to create gold products?
→After the work is finished, the 24-karat gold dust and fragments
are collected, and iron filings are removed using a strong magnet.
Melting this material restores it to 24-karat gold, allowing it to be
easily reused in future projects. When melting 18-karat gold scrap,
the silver and copper contained in the filings and scraps
oxidize, turning the material pitch-black.
(Point 3) Why is no solder used when attaching the gold granules?
→ 18K gold solder is used to join gold products. I believe the price
for 2g (melting point: 810°C) exceeded 60,000 yen in 2026.
The issue lies in the added metals in solder; once welded,
it is impossible to remove the solder that has flowed out.
(Point 4) Why is diffusion bonding not used to join gold granules?
→ Diffusion bonding is a solid-state joining process in which
the materials to be joined are brought into close contact;
pressure is applied to the metal surfaces at high temperatures
below the melting point of the base material to achieve
a bond through atomic diffusion. When a metal granule
is heated and pressed from above with a tool, it flattens.
Granulation is sometimes described as "fusing the granules to
the base material using thermal diffusion," but this is clearly incorrect.
Because the actual contact point between the granule
and the base material is infinitesimal—literally just a "point"
—a bond of sufficient strength cannot be achieved.
The online community "Ganoksin" was established in 1995.
On this site, one could read Professor Erhard Brepohl's explanation of
the granulation technique, titled "Goldsmithing Granulation Technique."
Prof. Dr. Erhard Brepohl
https://www.ganoksin.com/article/goldsmithing-granulation-technique/
At the time, I had several opportunities to visit Bali, Indonesia,
where I observed granulation workshops operating exactly as
Professor Brepohl had described. I have summarized the granulation
bonding process below; I hope you find this information useful.
(Step 1) Molten gold is dripped and rapidly cooled.
The resulting granules are sorted by size.
(Step 2) The copper piece is heated and oxidized.
Gain oxided powder from its surface.
(Step 3) The dried beans are ground to create a
fine powder for releasing carbon during firing.
(Step 4) Oxided copper powder and beans powder
are mixed in water to create a viscous paste.
(Step 5) The points where the gold granules will be
welded are marked on the gold product.
(Step 6) A small paste ball approximately 0.5 mm in
diameter is applied on the bonding point.
Put gold granules gently on the paste and
leave them in a cool place for drying.
(Step 7) Once dried, heat the product in a reducing
atmosphere using charcoal or a burner.
(Step 8) The oxided copper is transformed into liquid
copper in a reducing atmosphere.
(Step 9) Gold granules are welded to the base
gold product at their contact points.
Currently, training courses in gold granulation technique are being offered
and gold granulation jewelry can be viewed through image searches.
Ilias Lalaounis produces jewelry with gold granulation to order.
You can also purchase the company's past pieces at auctions.
Andrea Cagnetti, known as Akelo, has made a significant contribution,
and his works are housed in museums but can also be viewed online.
In addition to Ilias Lalaounis, companies like Zaffiro
are gaining recognition for their excellent gold granulation jewelry.
https://lalaounis.com/product/
https://www.akelo.it/en/jewelry/
https://zaffirojewelry.com/
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