Ancient Chinese art used a toxic lacquer made from a relative of poison ivy

On Christmas Day, I watched a documentary about the terra cotta warriors — thousands of clay soldiers built as funerary objects for the tomb of Qin Shi Huang, China's first emperor. One crazy fact I learned: Unlike the type of lacquer we call shellac today (which comes from crushed beetles), ancient Chinese artists used a lacquer derived from the sap of the lacquer tree, a relative of poison ivy. Anybody tasked with the job of applying that lacquer can end up with a serious allergic reaction. Another fun fact: We've still never seen the inside of Qin Shi Huang's tomb. Partly, this is a bureaucratic issue. But the larger problem is the mercury-laden soil on top, possibly contaminated by Qin Shi Huang's tomb, itself, which was supposed to contain a scale model of his empire, complete with rivers and oceans flowing with (you guessed it) mercury.


    1. Yes, cashew shells do contain an allergenic oil similar to the urushiol in poison ivy and such, and it is an issue for handlers. Now you know why you never see cashews for sale in the shell, unlike basically all other nuts.

    2. Also a relative of mangoes, which also have the oil in their leaves and saps, as well as the peel of the fruit.  If you’re sensitized to poison ivy, you can possibly cross react with the peel.  Whenever I see poison ivy in the wild, I feel disappointed off that there’s not a mango tree growing there instead.

      1. Over the years I’ve developed / discovered an allergy to mangoes, cashew, and pistachio — in that order — and the reaction has gotten worse. They all have urushio, which is in poison oak as well as poison ivy.

        1. Hmm. The last time that I ate pistachios, I got hives. I haven’t had any problems with mangoes or cashews so far.

  1. The sap is still used today in Lacquerware – people who work with it are supposed to develop a tolerance for it, like turkeys and deer do to poison ivy, which they eat.

    1. Interesting but needs to be confirmed.  I was told my a dermatologist that actually previous exposure to allergen such as urushiol increases the body sensitivity to later exposure and aggravates the symptoms: I apparently have been a text book case of it.

      1. I believe it’s dosage dependent, an exposure to a high dose can promote sensitization and a reaction, whereas a low steadily increasing dose can lead to tolerance, like they use for allergy shots.

      2. It might be that for people without a specific allergy to these oils will eventually gain a tolerance. Those of us with an allergy will get worse with continued exposure. I know that’s roughly how it works with bees, and as some one who’s dangerously allergic to urushiol I can certainly say I’m not getting any less dangerously allergic.

        As an interesting side note I’ve been warned not to handle Asian lacquer work for fear that I might react to even the dry stuff.

  2. Aha! One of Robert van Gulik’s Judge Dee historical mysteries has lacquer poisoning as a key plot point. At the scene of the crime someone has touched a newly lacquered table before it was dry, and has some nasty swelling or blistering to conceal.

  3. I remember reading something about a form of ladquer used in Japan that may or may not be the same thing, and that it’s handled pretty much exclusively by a small number of families who apparently don’t have the allergic reaction to it (which is probably how they got the job in the first place)

    1. There’s a series of videos on youtube showing the making of lacquerware – even if the maker isn’t allergic, his entire technique is very obviously designed to prevent any and all contact with the urushiol lacquer.

  4. So, when  high-doses of a heavy metal or other poison are found in pet foods or toys, it’s just an ancient Chinese tradition.

    1. The reservoir in my hometown was on the site of a Colonial era hat factory.  What could possibly go wrong?

  5. I would just like to say that when my time comes, I would like to build a model of my imaginary palatial estate and place it on my tomb as well. The landscape fountains will be flowing with mercury and the house will be insulated with asbestos.

  6. I’d like to say that shellac and lacquer are two distinct coatings with different properties that means shellac did not replace lacquer. Not a big deal, but the difference is very useful to finishers because they have different solvents and can be alternated in layers to produce decorative finishes. Shellac is used as a barrier layer also because it will not dissolve in the presence of hydrocarbons. Maybe I have provided you with a painless way to fulfill your quota of learning something everyday.

    1. beat me too it! and although a lot of traditional, ancient lacquers were derived from tree resins (just like turpentine), shellac isn’t the bug’s shell (although theres gonna be bug shells in there), but a natural resin they excrete after sucking the sap out of trees. it’s also a completely naturally occuring polymer! especially considering that the only solvent it needs to break it down is alcohol (unless you are using methanol you are looking at a very non toxic, natural substance) ! when most people say lacquer today they are usually either refering to nitro-cellulose (another cool thing in its own right!) or polyuerothanes (but between you and me  theres a reason why polyuerothane is usually just called clear coat, and not lacquer: it sucks in comparison)

  7. Partly, this is a bureaucratic issue. But the larger problem is the mercury-laden soil…

    This seems an odd way to put it. As the linked article says, the main problem is less the dangers and more concern about damaging the artifacts, the way the Terracotta soldiers lost their paint right away. That’s almost the opposite of the usual red tape, since it’s a rare example of planning for the long term.

    1. Good point chenille, thanks for the reminder. I remember that when the researchers first opened and gazed upon the terracotta soldiers, they were painted in lifelike and vivid colours and within a crazy-short time, the paint interacted with the newly introduced air and disintegrated as they watched. Since then, the scientists have been very, very careful about how new discoveries are approached and handled. The researchers were able to use forensic chemistry to make computer models that approximated what they saw when they first opened the chamber, but, you know, like the song says, “…ain’t nothing like…”

      I just skimmed the WikiP article and while it mentions how the figures were originally brightly colored, It doesn’t really say anything about the near instant degradation of of the figures upon contact with new air — but I’m certain I’ve seen this from a couple of sources – just cannot remember where.

      Wait…wait…I just did a bit of looking, I’m wondering if I misremembered about the color instantly flaking. Maybe I was thinking of some other relics ’cause I do remember reading about the instant degradation somewhere.

      Anyway, here’s the link, I’ve read the first two or so pages, looks like a good article:

      and another,

  8. Fun fact: the word for the stuff in poison ivy that makes you itch is “urushiol.” “Urushi” is the Japanese word for the lacquer tree, or for lacquer.

  9. I thought shellac was made from the excretions of beetles, not the beetles themselves. Wikipedia suggests that the bugs are sort of a “bycatch” in the collection process.

  10.  People have varying degrees of sensitivity to poison ivy. Much of my family has a general immunity to urushiol oil, though my brother gained an allergy after excessive exposure. He has since regained his immunity though, after many years.

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