The Art of Granulation— The Different Methods Used to Fuse Gold Granules to Gold

Granulation jewelry is just gorgeous. Tiny gold spheres fused onto gold surfaces create incredible mosaic patterns. Archeologists have found Sumerian jewelry featuring primitive granulation as far back as 2800 BC.

But have you ever wondered how jewelers make granulation pieces? Attaching hundreds of delicate beads per inch seems difficult and time-consuming!

Hard Facts on Soft Metals

Now you may be wondering...if gold and electrum (the gold + silver blend) are soft, malleable metals, how did ancient smiths get those little round gold bits to stick on firmly and stay put? The secret to making the round gold balls adhere lies in applying high heat and some good old chemistry.

In short, jewelers carefully cut sheet gold into perfectly shaped granule beads using specialized tools. Then, the magic happens when heat and chemical reactions form potent bonds between the granules and base.

Hard Soldering by Hand

Okay, first, look at the most labor-intensive way to attach granules - hard soldering.

The hard soldering method involves a jeweler physically positioning each granule where they want it using tweezers or a tiny paintbrush. Just a little pressure pushes the bead into the metal below, ensuring it stays put.

Then, using a soldering tip, they heat the exact spot where the granule meets the base to fuse them. Multiply this by potentially thousands of granules, and you're talking about crazy amounts of work!

No wonder few choose to granulate this way.

Puddling Problems

An upgrade over hard soldering is using a paste flux mixture. The jeweler dabs flux on the base metal and sprinkles over gold beads. Heating the piece melts the solder in the paste to attach the granules.

But this leaves ugly, gloppy solder residue blobbed around each bead. Jewelers then must tediously file and polish the solder away to clean up the piece. It's not fun.

Finessing the Fuse

Experts think the gifted Etruscans used a much more elegant method called fusion bonding. What's notable here is the base metal and granules contain the same gold alloy.

The jeweler lightly brushes a diluted flux onto the base to temporarily hold the granules where they want them. Then, the whole piece goes into a furnace without oxygen. When the temperature hits the alloy's melting point, the base and granules magically fuse right where they touch.

And because the lack of oxygen prevents oxidization, the flux burns off without a trace. This method leaves an immaculate connection with no messy solder or puddles!

Colloidal "Glue"

Other historians think the Etruscans perfected colloidal soldering instead. This method calls for painting a mixture of plant gum and copper salts onto the base gold as glue. The gum temporarily affixes the granules in place.

Firing up the furnace burns away the organic gum and releases the copper into the junctures between granules and base. When the temperature hits 890°C, the copper enables incredibly durable bonds to form.

The advantage here is it takes less heat, so the delicate beads don't risk melting before the bond sets. Either way, Etruscan jewelers had mad skills!