18K Gold Made With…Plastic???

Scientists have kind of done what alchemists have been trying to do for centuries. Science has found a way to make 18 karat gold using a mix of protein fibers and polymer latex instead of the usual recipe of gold and base metals.

First let’s dive into why we have 18k, 14k, and other versions of gold in jewelry. Pure gold is way too soft for everyday wear so it’s mixed up with metals such as silver, copper, nickel and even zinc to help give it that backbone. Karatage (K) is denoted by a number and the K means purity or how much of the gold is in a piece of jewelry. 24K is the purest form of gold.



“This gold has the material properties of a plastic,” says material scientist Raffaele Mezzenga, from ETH Zurich in Switzerland. This substance is a gold foam and it has the same toughness, strength and heat resistance as regular 18K gold. The major difference is that this plastic gold contains tiny invisible air pockets that make it lighter-due to the uses of plastics instead of metal.

The final density of this plastic gold is just 1.7 g/cm3 which is less than the weight of actual 18K gold.


The Recipe To Make Plastic Gold


To make this gold they mixed gold nanocrystals, protein fibers, and a polymer latex with water and salt to create a gel. Then they replaced the water with alcohol and put it into a high-pressure CO2 chamber so that the alcohol could react with carbon dioxide and create a gossamer-like aerogel.

After that, apply heat so this aerogel can be molded into whatever you want it to be. You need the heat to be 221 degrees Fahrenheit which is well lower than the heat needed to melt pure 24k gold (1,947 degrees Fahrenheit.)

“This new 18-carat gold can fill a niche which is currently unoccupied in the realm of industrially relevant gold blends and open the way to unexplored applications,” write the researchers in their paper. This isn’t the first time Mezzenga and his team created gold. They also created a super-light gold from milk protein. It was light enough to float on top of a cup of coffee!! However, it’s properties made it difficult to get it into places where gold needed.


My 2.5 Cents


I honestly don’t know how I feel about this. On one hand, this would help make gold jewelry affordable and reduce plastic waste in some areas. On another hand, it really devalues a piece of jewelry. Sure it could be marketed as “green” gold jewelry-green meaning that it’s using plastic and when you use plastic in gold like this then it won’t pollute our environments like plastic ware or even water bottles.

One cool thing is that the researchers found out that they could change the colors of the new plastic gold. They were able to do this by mixing in smaller particles of gold into the aerogel solution. Below, from left to right we have a foam of amyloid protein filaments without the gold. In the middle we have the gold aerogel made gold microparticles and on the right is gold aerogel made with gold nanoparticles.

Researches did say that the plastic gold can be used for jewelry, watches, chemical catalysis, electronics applications, and even radiation shielding so I do believe this is a really cool breakthrough especially when it comes to technology. Perhaps SpaceX could use this substance. I honestly prefer actual gold to the idea of plastic gold, but I would be willing to make a piece of jewelry from this material just to say I’ve done it. Perhaps we have seen the evolution of gold?

All images by ETH Zurich