Wednesday, June 1, 2011

Tips on How to Use Boiled Eggs for Metal Patination

By on Wednesday, June 01, 2011 21 Comments

Image by Irene Helm
There are a number of ways to patinate metal (see my past post on 8 Ways to Patina Jewelry).

Some of the ways are stinky - LOS or liver of sulfur (potassium sulfide) and ammonia are two examples  - and also need to be used with care.

Hydrogen sulfide which has the characteristic smell of rotten eggs, is released during the use of liver of sulfur. It's poisonous in large amounts, so good ventilation is vital especially if you oxidize metals a lot.

LOS should be stored well away from any acid.  Pickle (acid) solutions used to clean metals after the soldering are a prime example.  Very dangerous levels of hydrogen sulfide will be created if the LOS is allowed to react with acid solutions.

So if all the above really scares you, rest assured there is a cheap, easy and safe way to patinate your metals. Just use boiled eggs!  Eggs are rich in sulfur-containing amino acids which are the building blocks of proteins.  The aroma of cooked eggs is quite complex but one of the contributing gases emitted is a small amount of hydrogen sulfide. Rotten eggs smell that way because greater amounts of hydrogen sulfide gas are released with bacterial decomposition.

Check out the boiled egg technique tutorial by Irene Helms. It's really neat because she uses just 1 boiled egg in a plastic bag.  It's so much more convenient than putting everything in a jar because she could easily turn over the bag several times to ensure even oxidization.  It took her only 15 minutes to oxidize some silver bails.

However, if you google the technique, there are variable results with this technique. Some, like Irene, say the yolk works better but one person I came across swears by the egg white. Then there are those who can't make it work even after days.

So it's time to put on my scientific hat, er, coat and conduct a  few experiments to sort out some of the discrepancies.

Experimental protocol :
I boiled 5 large eggs by placing them in a pan covered with water. When the water reached boiling, I closed the lid, turned off the heat and let it sit for 20 mins. I rinsed the eggs a few times with cold water.  One egg was boiled the night before and left overnight on the kitchen counter.

The next morning,  the other 4 were boiled and then quickly cooled in cold water. All 5 eggs were halved with a knife, shell and all. The "day-old" and one "fresh" egg were placed in plastic zip lock bags. 2 "fresh" eggs were placed in a lidded glass container and on a saucer respectively. The egg white and yolk were separated for the 5th egg and each component was placed in plastic bags. The eggs were mashed up further using my fingers. 2  round copper beads were used per container - one directly on the egg itself.

The copper beads were closely observed for an hour.  Why an hour?  If there are going to be any useful changes, it should have effectively done so well within the hour. Besides I wasn't keen on having rotting eggs for too long!

What I learned is included in the following :


Use Uncoated Metal
This technique will obviously not work for coated metal because the metal is not exposed to the hydrogen sulfide.

Metals to use
The method will work for copper, bronze, brass and sterling silver as the latter contains 92.5% silver/7.5% copper. But it will probably take a long time to oxidize fine silver (99. 9% silver) so don't do it!  Save the fine silver for shiny designs.

Rough Metal surface
Generally a shiny surface will take longer to oxidize than a rough one.  It's too smooth for the process to easily get started. This is the reason why many artisans like to tumble their finished pieces. Not only does it work harden the piece, small surface imperfections are removed so it will take longer to tarnish.

I did not roughen the copper balls I used. Therefore it took longer to "turn" them dark than Irene's textured silver bails.

Hard-boiled Not Soft-boiled Eggs
It's not just that soft boiled eggs would be a runny mess. The longer the cooking time, the stronger the aroma. That's because the egg protein denatures and coagulates with heat and time, releasing its sulfur content in the form of hydrogen sulfide. That means more gas is available for the oxidizing process. Stick your nose to a hard boiled egg next time you cook one and you'll smell what I mean! 

It did not make that much difference using a freshly cooked egg and one that was cooked about 12 hours before hand. The oxidation was visible through the plastic bags within minutes for both. It was slightly faster for a freshly cooked egg in the first 5 minutes. The pictures below show the greyish areas on all the beads. The dark areas are more pronounced for the lower beads which were those placed directly on the mashed eggs and thus closer to the gas release.

Break Up the Egg
Breaking or mashing up the egg into smaller pieces means the boiled egg's surface area is increased, and so is the amount of gas released.

Use a Container
The beads on an open plate failed to oxidize at all because the relatively small amount of gas given off after cooking was not trapped and soon dispersed into the room atmosphere.  They looked exactly like the shiny control (untreated) beads!

Irene's use of a plastic bag is inspired because the space for the gas inside is small so it will fill quicker. But even a larger container will still work as shown by the oxidized beads below. Her method though is good for turning over pieces without opening the container. The gas naturally escapes if you keep opening the container to look!

 If you look at the lower bead shown in the picture above, it was the most oxidized of all the beads. The glass container  had a slight edge on the plastic bag method because the static cling around the beads probably excluded access to the gas.  I had to frequently move the beads in the plastic bags to counteract the static cling. If you are going to use plastic bags, try coating them inside with a small amount of baby powder before using themIt'll prevent the sides of the plastic bags from sticking together.

Whole Egg Or Whites, Not Yolks
This tutorial on Wikihow advocates the use of a rack to hold the metal pieces above the egg yolk.  The position makes sense as the gas will rise up. However, I suspect the reason why it took a day or so for this method to work is the use of only the yolk.

Sulfur is indeed yellow in color so many people mistakenly think the yolks are sulfur rich. Egg yolks are that sunny hue not because of sulfur but organic pigments called carotenoids. The sulfur present in eggs exist not as the free element but as disulphide bonds linking amino acids. These weak bonds break up during cooking.

According to Harold McGee (see reference below), most of the hydrogen sulfide forms in the egg white. So was he right? Yep. The pictures below are proof. The egg yolk only beads had almost no sign of oxidation unlike the egg white ones after 1 hour.

So use either the whole egg or just the white McGee also says older eggs will generate more hydrogen sulfide. Also, if you have a lot of metal to oxidize, one egg may not be enough.

Would you eat the egg afterwards?  I let you be the judge! Here is the egg white after I removed the copper bead :

Patination Safety Considerations 
Harold McGee (2004) On Food and Cooking: The Science and Lore of the Kitchen Excerpt
Wikipedia : Egg Yolk

More Tips and Tricks :
Original Post by THE BEADING GEM
Jewelry Making Tips - Jewelry Business Tips 



  1. Thanks for doing the research! I've been wondering abt them eggs:-)

  2. Thanks Pearl for sharing your scientific expertise. Bet you had fun doing this!!

    I am always happy to hear about a safer way to do things.

  3. Ha! Superb resource, thanks for all the work, Pearl! I must run to the grocery store...

  4. Wonderful Pearl, loved this post. Funny how delicious an egg can look when it's been neatly cut in half and the hard boiled yolk blended with mayo, mustard, relish, salt, pepper and paprika to make attractive Deviled eggs and how terribly UN-appetizing they look when they've been smooshed to pieces in a plastic baggie. Of course the copper beads thrown into the mix did little to make them appear more palatable. :D

    But in all seriousness there have been times when I've wanted to add some tarnish or patina to beads for a more "vintage" look but just never wanted to invest in hazardous chemicals like LOS. So now I know. Thanks. :)

  5. Your delicious aside about deviled eggs sure made me hungry! I love them as I do egg salad sandwiches. Yes, those copper beads were the bling!

    Patination with LOS is very fast though and fine to use so long as one knows how to use it safely.

  6. I've never done it so thanks for doing the research! And um no, no eating that egg for me thanks!

  7. What a great post! Thank you so much for doing the research and clearing up some myths.

  8. Awesome info Pearl! I was thinking of using this method after I just discovered my hardly used Liver of Sulfur wasn't working anymore. Since I don't do it that often, and I always have eggs, this seems like a more economical way of going about aging my metals.

  9. Yes, unfortunately LOS goes "off" with time. So it is worth considering boiled eggs for the occasional patination.

  10. Great! When I apprenticed with a silversmith, she had me oxidize using a commercial acid wash. Freestyle, while she told me that if I spilled it I would destroy her studio before we could don HazMat suits.

    I like eggs.

  11. That's a funny story but she is right about being careful with acid!

  12. Can I oxidize gold with this method? If don't, how can I do it, please?


  13. No, you cannot do this with gold. The reason gold is so highly prized as a jewelry metal is because it is stays the same luscious yellow color without oxidizing when exposed to air or water. You can use very strong acids to chemically dissolve gold but that is not the route for jewelry makers!

    If you want the look of oxidized "gold", I recommend you work with jeweler's bronze (85% copper 15% zinc) which looks like gold but can be patinated.

  14. Could I let an egg "rot" (so to speak) to achieve more intense results? Maybe leave the egg outside for a day or two in the hot weather.

  15. Thank you so much for this post! I bought a beautiful bee ring from Etsy and had to get it resized. When I picked it up, all of the patina had been taken off :( you couldn't see the details on the bee at all any more. I read that egg yolk would work, so I hard boiled an egg and left the ring with it in a baggie in the fridge for a week! Of course that didn't work. So I cooked another egg after seeing your post, and mashed up half in a glass jar while the egg was still hot, dropped in the ring, put the lid on the jar, and an hour later... All black! I shined up a few parts and now it's perfect again. Thank you, thank you!!

  16. Samantha, thanks for sharing how you repatinated the ring again! So glad to know when someone learns from my posts and puts it into practice!!

    The hot egg probably hastened the patination too.

  17. Patination- There are many recipes for colouring 925 Silver (found in
    books in most libraries)Fine silver does not oxidise easily,it is mainly the copper content,.75% that takes the colour, thus to keep your silver white quench repeatedly in your 1/10Sulfuric acid.
    Many garden fertilisers contain high levels of sulphur and other agents that will give you interesting affects.Experiment!!
    Hint by Phoebe, professional designer/maker.

  18. Is there any way to make a rainbow tone without using LOS?

    1. Yes. That would be heat patination. Works very well with copper. See this example -