Making 1000 Year Eggs

So, as promised, I spent several hours yesterday making 1000 Year Eggs.  That is, I coated a dozen and a half duck eggs with caustic mud, rolled and pressed them in rice chaff, and set them aside to dry.  Later I placed them in a soil-lined ceramic crock and will let them sit for three to three-and-a-half months, before checking to see if I did it right.  I’m sure if they start to rot instead of chemically change, we will be aware of it.

To start off, the eggs in the mud looked like this:

Duck Eggs Caustic Mud
Duck Eggs Caustic Mud

Then one thoroughly (and evenly) coats them with the mud:

Coating the Eggs
Coating the Eggs

And lastly, after they are covered with rice chaff, they look like this:

Eggs Coated with Mud and Chaff
Eggs Coated with Mud and Chaff

And now we wait. . . three whole months for the chemical conversions to take place inside the egg. After the ingredients to make pidan are mixed, the following chemical reactions take place:

CaO + H2O -> Ca(OH)2
Ca(OH)2 + Na2CO3 -> 2NaOH + CaCO3
Na2O3 + H2O -> 2NaOH + O2
K2O + H2O -> 2KOH

*The Na2O3 and K2O are from the plant ash

Because of the porosity of the egg shell, NaOH is first adsorbed to the surface, and, owing to a change in the osmotic pressure, NaOH enters the egg through the pores and subsequently penetrates the semi-permeable membrane, coming into contact with the egg protein, causing it to become denaturized and hydrolysed into polypeptides and finally into amino acids.

The result is that 1000 Year Eggs are much higher in protein and much lower in carbohydrates than unpreserved duck eggs. Other nutritional elements such as amino acids and fatty acids are about equal between the two egg forms, although the preserved egg generally has a bit less of everything in it.

The recipe follows:

1000 Year Eggs

3 – 4 cups black tea brewed very strong + strained tea leaves
2/3 cup sea salt
3 cups wood ash
3 cups charcoal ash
1 ¾ cups quicklime

18 fresh duck eggs
2-3 pounds rice chaff
Latex gloves

I procured all of the ingredients from internet retailers except the wood and charcoal ash which our neighbors were generous enough to donate to the project in exchange for a chance to taste the bounty of the experiment. We also had the sea salt and tea on hand.


  1. Brew the tea. I used at least a cup of loose tea leaves for 8 cups of water (I did say strongly brewed, right?) Let the tea sit for at least an hour to get really strong. In the meantime, find a large, non-reactive vessel (like a plastic painter’s bucket or other very large and deep bowl) and put the salt, ashed and quicklime into the bowl. When the tea is done, add about 3 cups and stir well. Then strain the tea, preserving both the liquid and the solids and add the spent tea leaves to the mud mixture. If necessary, add more brewed tea until the mud is a thick, but not watery solution.
  2. Put on latex or other protective gloves. The mud is caustic and will cause skin discomfort.
  3. Place the first batch of eggs into the mud and coat them well. I let mine sit for about 15 minutes before moving on to the next step. Find a large, deep bowl and fill it with rice chaff. After the eggs have rested in the mud, take them up one at a time and make sure they are completely coated. I found that the mud was a bit sticky and almost serous and didn’t want to adhere to the surface of the shell. When the coating is more or less uniform, place the egg in the chaff. Wipe excess mud off of your gloves by scraping on the edge of the vessel holding the mud. Then take handfulls of chaff and cover the egg with it completely. Pick up the egg and put chaff on the reverse side if needed. Then lightly compress the egg in your hand to try to get the chaff to bond with the mud. Remember the egg is raw and don’t squeeze too hard. When the chaff fully coats the egg (add more chaff if necessary), set it on a plate and move onto the next egg.

When all of the intended eggs are coated with mud and chaff, clean up. I let my eggs sit overnight before burying them in soil and lime. I used soil from outside (not potting soil) to fill the crock to get some natural microorganisms in the mix. If you have a choice of soils around your yard, use one with a high clay content. Set crock in an out-of-the-way place outside and wait a few months. I placed my eggs in a decorative sort of crock and put the crock in the garden as an ornament. Water is crucial to the process and the crock needs to be open to the rain to get wet and dry in cycles.

The reaction that causes the preservation proceeds more rapidly in warmer weather than in colder weather, so I will be waiting the full 100 days before checking on the eggs. Then you can look forward to posts exploring the flavor of these, wonderful ancient delicacies. (Words and recipe by Laura Kelley; All Photos by Laura Kelley)


61 thoughts on “Making 1000 Year Eggs

    • Hi Mike:

      Stay tuned and I’ll let you know. Look for the harvesting of the eggs post around mid-May sometime. I’ve had them in China a few times and like them. The aroma can be a bit off putting – very strong ammonia smell, but the flavor is strong and un egg-like. Savory, a bit creamy, almost like a “stinky cheese”.

  1. Goodness, you are a brave woman. How remarkable to make them..Can’t wait to see the result. I’ve never had them before. And you even know what the chemistry of the magic is. Bravo.

    • Hi Deana:

      I have had it in mind to make them ever since I first tried them years ago. I’ve been researching and gathering info on them for years – and of course enjoying them whenever I can.
      Thanks for stopping by!

    • Hi Marisa:

      I take Chinese food origin stories with a drop of a hat. They are just stories, usually with no basis in anything resembling fact. For example, the story goes that tea was “discovered” when a leaf happened to float into an emperor’s cup of hot water. That ignores the fact that the Burmese were enjoying tea as both food and drink for centuries or millenia before the Chinese “discovered” it an began to mass produce it in great plantations in the south.

      That said, the story behind the eggs is that a Ming farmer in Hunan Province found duck eggs in a pool of lime water that had formed where he had mixed mortar for construction. He tried them and accidently discovered 1000-Year Eggs. This same man went about trial and error to replicate the process, and that is pretty much the traditional process that I used today. I wouldn’t put to much faith in that story. But that’s the best I have for now.

    • Hi Mike:

      Welcome to Silk Road Gourmet!

      You asked the smae question as Marisa did. Please see my answer to here for your answer as well. . . Come back soon!

  2. Brilliant! I tried tea eggs a few years back, not a particular success but a good exercise nonetheless. Certainly a less thorough process than yours, Laura which no doubt explains a lot!

    • Hi Miles:

      I like tea eggs made in very strong tea and allowed to sit for a long time so the tea really infuses into the egg and makes wonderful patterns throughout the substance of the egg. Try making the tea much stronger than you woudl drink or lettign them steep longer. . .that is if you want to try to make them again.

  3. Actually, it’s “century eggs” so 100-year old year eggs 🙂

    We get them quite easily in Singapore so there’s no need to make our own but they taste wickedly good

    Suggested serving – mash them up with minced pork and steam them with eggs to make a pidan custard

    We also have another dish where we add pidan, salted egg and normal eggs to sauteed spinach – wicked as well 🙂

    • Thanks for the suggestions. I have quite a few recipes and will probably post a few when the eggs are “cured”. I am leaning towards one of the pork recipes so I can call the post, “Green Eggs and Ham – Chinese Style” or something like that! Come back soon!

  4. Very cool. Almost the same way I did it. Where did you find rice bran? I used bamboo leaves, which one time worked, the second definitely didn’t, and I have no idea why.

    • Hi Ken:

      Still waiting for the outcome so I can write my, “Green Eggs and Ham” post with a 1000-year egg and pork stir fry! Hopefully they will turn out OK. As to the rice bran. I do a lot of shopping online since we are in a somewhat remote area and my time is extremely limited. I think it was someplace in the midwest US that shipped it to me. I just trolled around on the internet until I found it – a bit of a haul to find unprocessed bran, but it might have been a feed store for horses or other aggi animal types. Minimum order of 5 or 10 pounds.

      Actually, for you I checked the shipping label on the box and it is from – a homebrew and winemaking supplier in St. Louis.

  5. I am very interested in the 100 year old eggs….we spent 3 months in Beijing in 2008 and discovered them very late in the trip…we liked them a lot! have they been smelling ok so far?

    • All is well with the smell. They are buried in soil in a large crock. No odor or anything unusual about them. I will harvest them later on this year – perhaps in the summer. Thanks for writing!

  6. Eagerly awaiting the results of this recipe! Have you tasted 1000 year eggs before so you will be able to compare?

    • Hi Tanya:

      Will check on them later in the summer. In Uzbekistan now . . . And, yes I’ve had them before, so I know what to expect . . .

      Thanks for reading and commenting!

  7. I’m about to start my own batch of eggs with a food grade NaOH + Salt solution and came across this page. Amazing! I guess I can still use the NaOH for making pretzels. How does one get wood ash and charcoal ash if living in the city? Thanks!

    • Hi Cindy:

      I suggest buying a small portable grill and making the ash yourself or finding someone who already has one and using theirs. When I lived in NYC, people used to use them on balconies, legally or illegally. Water plays a big part in catalyzing the process, so make sure the eggs get moist after they are coated and dried. Good luck!

  8. What an exciting experiment.
    Century eggs taste great with pickled ginger (the kind served with sushi).

    • Ginger slices and a preserved ginger were on the table as condiments the first time I tried them in Xian – delicious. At some point I am going to use them in a pork stir fry and write about it. The title of the post will be, “Green Eggs and Ham”.

      Glad you stopped by and commented.

  9. I’ve been following this for months. When will you try the eggs. It’s August now…almost September. I love these eggs and used to eat them many years ago when they were made in China Town in SF. You would find the in large earthenware crocks. Now they come from China and are not at all the same. Besides that, there have been scandals with contamination

    • Hi Carla:

      The eggs have been taken in and by feel most of them turned out fine. There were only 2 that felt too loose to have been properly converted into 1000 year eggs The good ones have been washed and are sitting in the fridge for future use. I have pictures of the cleaning of the eggs and will post them soon, perhaps with a simple eggs with pickled ginger picture.

      The biggest reason for the delay was a leak that caused massive damage to the basement and first floor of our home. We had contractors in all of June and July to remediate the water damage and rebuild the rooms. Now that is taken care of, I can get back to some of the long-term projects, like the eggs.

      Stay tuned.

    • Hi Leslie:

      Sure. You can use chicken eggs, or any sort of egg. I’ve even seen this done with itty-bitty quail eggs. The important points are that the eggs must be fertilized (available online), and that they must be in a container exposed to rain and weather etc. Good luck!

  10. I’m Asian and I don’t even know how to make this type of egg lol thanks for the recipe. Just recently heard that China is tempting to speed up the process and they add other chemical into the ingredient that would be harmful to your health. That’s why i try to research the recipe to make my own.

    How you ever thought of letting it sit there for your next generation? Really making it 100 year old egg? It might actually worth something. Lol

    • Hi George:

      Welcome to Silk Road Gourmet. I know it seems odd – I get these really surprised looks from a lot of Asian folks when I mention having made 1000-Year eggs at home. Its not something they ever considered doing, and they are really shocked when they find out that an anglo has done it. Why is the unspoken question. . .

  11. Laura, I now have sources of duck eggs, wood ash, and charcoal ash, so I’m going to give this a try. I would like to know more about the aging, though. What kind of crock? The crocks I know of are for pickles. The eggs would end up sitting in mud, not drying out. I’m imagining a large terracotta flower pot but would like to know what you used. Stacked eggs, or single layer? Sun or shade? And when you say to bury them in soil and lime, do you mean add more quicklime to garden soil? Photos would be a big help with this step, which sounds both important and tricky. Thanks, Karen.

  12. Hi Karen:

    The eggs have to be FERTILIZED, or the process will not work. If you have sources for fertilized duck eggs then the game is on (fertilized chicken eggs, or fertilized eggs of any kind, will also work).

    After the eggs are coated with the mud mix and chaff they need to dry overnight or for a couple of days before putting them in the crock.

    I used a large ceramic crock bought at a garden center. It did have a hole in the bottom, but I covered it with some rocks then a few inches of outside soil (not sterilized potting soil). Then, I alternated layers of eggs and soil, covering each with at least an inch of soil in between layers of eggs. The last layer of soil should be 2-3 inches thick with another 2-3 inches to the top of the crock.

    I mixed a bit more lime into the soil. Perhaps 4-5 parts soil to 1 part lime. Our soil here is not very sweet, so for me this was an important step.

    If you are going to do this now, I would start it in the shade, but in a place where it will catch the rain. The more rain – the better. As it gets cooler, you may wish to move it to a sunnier spot. The process takes 3-4 months in warmish weather and longer if cool-to-cold. When the appropriate time has elapsed, take one egg only and check to see if it is fully transformed. If it is partially transformed, let the rest of the crock go for another month before trying another egg.

    Once potted, the less you do to the crock, the better.

    If you have more questions – please ask.

  13. Thank you for sharing,
    I had these egg with rice soups and peanuts. Omg so simple yet so wonderfully good.

    • Hi and thanks for stopping by! I’m glad you like the 1000-year egg posts! There are so many delicious recipes! These are just a few of my favorites.

  14. Hello There,

    when you say wood ash does it have to a specific kind of wood and charcoal ash is that the regular charcoal ash the Kingsford briquette’s and the lime I can use the home depot lime of specific type and place to get it?

    Thank You!


    • Hi Randall:

      I just asked our neighbors – who cook outside on wood or charcoal if I could have some ashes. I don’t think they gave me anything special. Ditto on the lime. The hardest ingredient to find were the rice hulls, but Midwest Brewing Company had them. Good luck!

  15. Just wanted to thank you for sharing this recipe. I wanted to make 1K eggs and searched throughout all internet before finally finding your great article.

    Now, the only question I have is weather I can skip a part of: wood ash, charcoal ash, cups quicklime?
    I know that there is a recipe to put eggs into the solution of salt and sodium hydroxide for 2-3 months, do you think that this will have the same effect? Do you think you might experiment in the future what works best and if there is any difference in taste?

    Thanks in advance!

    • Hi – thanks for visiting the site!

      I really don’t know if skipping or substituting ingredients will have the same effect. Without a detailed analysis, my knee-jerk response is to keep to the recipe and not cut corners. In looking at the chemical analysis, there seems to be a role for each of the traditional ingredients to play. Also, although lye (sodium hydroxide) is produced in the traditional production method, it is usually produced with a calcium compound that would mitigate its very caustic nature. Also, it is a bit tricky to work with – you risk dissolving the container if the concentration is too high or even a possible explosion if there is too much water left in the mud. Lastly, there could be residual lye left in the intended-to-be edible final product. I am a biologist, not a chemist, so not an expert. That said, I wouldn’t try to cut corners with lye, and have no plans to. Thanks for the question, though. I enjoyed it!

  16. Hi Laura,
    Thanks for sharing.. I am curious why the eggs have to be fertilised as that would practically rule out the hen eggs we purchase from the supermarkets. I thought what matters is the protein conversion of the egg white and not that of the embryo (My dad used to run a hatchery years back)..

    • Hi Song:

      I don’t KNOW the answer to this question, but I can speculate. First off, the yolk contains almost half of the protein of the egg and virtually all of the lipids. Fertilized eggs are higher in essential free amino acids (EFAA) and monounsaturated fatty acids (MUFA) contents but lower in cholesterol and polyunsaturated fatty acids (PUFA) than unfertilized counterparts. Fertilization decreases the lipid content. Fertilized egg proteins increase in hydrophobicity and decrease in electrostatic interaction. Beyond the fact that fertilized eggs are often favored in China culturally, I’m thinking that the decrease in lipids and electrostatic interaction coupled with the increase hydrophobicity allow the chemical conversion of the eggs (including the significant rise in pH) to proceed more quickly and completely. If you want to run a controlled experiment converting the two types of eggs to Century Eggs – please do – but please also report your results back here so we can better understand!

  17. I just cracked open a batch of century eggs. Yikes! They’re like explosive little pus pockets. One tap and the shell explodes (a little) and out pours a sulfurous goo. The yolk turned into a forest green disc.
    Dumb question. Should I have hard cooked them first? I left them in for an extra four weeks–is that what killed them?

    • Sorry it didn’t work out for you! No, you don’t cook them, they should be hard or rubbery when you take them out. The yolk sounds like it processed correctly, or at least partially so, the white didn’t. Did you use fertilized eggs?

  18. Lauramk:
    I processed 1 doz supermarket cage-free chicken eggs and 1 doz duck eggs from happy ducks. I used rice instead of rice chaff. Could that have been the problem? My soil was also dry….
    Anyway, I don’t have many failures so this is completely OK.
    Thanks for the reply,
    “jersey girl in portland’

    • Hi JG: Cage-free or “happy,” doesn’t mean they were fertilized. I’m still thinking that is the issue, but the soil should be damp-ish. How is the soil dry in Portland? Lots of rain there. Anyway – sorry it didn’t work for you.

  19. Thanks for the detailed recipe! Did you notice any heat produced when mixing up the mud? The first reaction in your list (CaO + H2O) is exothermic and there are videos on youtube of people blowing up stuff with it. Couldn’t one just start with slaked lime ( Ca(OH)2 ) to begin with?


    • Hi Bernhard:

      I think it is the degree (or size) of the reaction that matters. Nothing blew up in my container, I can assure you. We used to throw sodium bombs into the local reservoir as kids. This is not as interesting as that!

  20. hii Laura..

    Since you have taken so much time to study the process.. can you pls elaporate it more clearly what each ingredient does in the making of 1000 year egg ? century egg.

    i hav being meaning to make it.. but i heard ppl are using food grade lye.. that puts me off..
    i don’t like to eat chemical that directly that i have to put eggs in lye..
    now that i saw you use natural way.. i would love to know more.

    Although i am chinese myself.. i use to eat century egg when i was young.. adore it when eat with plain poridge.. eat just like that is yucky to me.. i like the dark translucent layer which was once egg white….. the yolk is good with poridge..

    I asked before i am in Germany now.. i can’t get rice chaff and some other natural ingredient you use…
    and those chinese tea leaves are full of pesticide which i reluctant to use. ..

    so i hope you can elaporate more of each ingredient do.. so i may find substitute for it.. to a more healthy ingredient and availability..

    if you make a video of it in you tube of the whole length process and the outcome it will be wonderful..

    thanks again.
    nicely done.


  21. Hey, I read your blog and I am very much impressed with your eggs. I am Planning to make my own using your method.
    I Have rice ducks laying eggs every day, at least 10 eggs every morning, I made salted eggs and was very successful.
    Anyway, I think I can get the materials except for the tea. I live in a province here in the Philippines and tea is scarce, can I use commercial tea, you know, those made by Lipton on a tea bag. what can I use if those are not good enough?

    • Hi John: I’m a little wary of saying yes to using commercial tea, because of the processing it goes thru. Perhaps order dried tea leaves from abroad via the internet? Best of luck!

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