✍️ Didier Fallières – March 30, 2022 – 2 min read
Update on Rhus Dermatitis Post : February 24, 2025.
Rhus dermatitis
In light of the growing interest in traditional Japanese Kintsugi, it is crucial to remind everyone of the fundamental rules for using urushi lacquer.
Recently, I have received several reports from Kintsugi practitioners who did not adhere to the protective measures when handling Ki-urushi lacquer. Unfortunately, they developed Rhus dermatitis, a well-known allergic reaction, with symptoms that can sometimes be severe (photos provided).
What is ki-urushi?
Urushi, used particularly in kintsugi, is a natural resin extracted from the Toxicodendron vernicifluum tree, also known as the “lacquer tree.” Used for centuries in Japanese craftsmanship, this resin is essential in making urushi lacquer, which is used to embellish and protect various objects : boxes, furniture, kitchen utensils, and ceramics restored using kintsugi.
Urushi refers to raw lacquer, applied in successive layers on wood, metal, or ceramic. Its hardening process, which can take several weeks, requires a specific environment, as urushi polymerizes in the presence of moisture rather than oxygen. Once dried, it provides a shiny, durable, and resilient surface.
Composition of Urushi Lacquer
1. Main Components
• Urushiol (30-75%) : The primary active ingredient, responsible for the adhesive and hardening properties.
• Water (20-60%) : Necessary for the polymerization process.
• Proteins and enzymes (5-7%) : Facilitate polymerization in the presence of moisture.
• Gum and polysaccharides Improve the elasticity and strength of the lacquer.
Urushiol and Rhus Dermatitis: Causes and Symptoms
What is urushiol?
Urushiol is a mixture of phenolic compounds found in the sap of Toxicodendron vernicifluum, as well as in other plants from the Anacardiaceae family, such as :
Poison Ivy
Cashew tree
Lacquer tree (Toxicodendron vernicifluum)
How does it cause an allergic reaction?
When it comes into contact with the skin, urushiol quickly penetrates and triggers a delayed immune response (type IV hypersensitivity), causing:
Redness and skin inflammation
Blisters and burning sensations
Persistent irritation
Intense itching
⚠️ Warning : Even urushi vapors can be harmful to sensitive individuals.
It is essential to always wear gloves, protective clothing, and a mask, and to work in a well-ventilated environment to prevent these issues. Urushi lacquer is a fascinating material, but it must be handled with care !
Essential precautions when using urushi lacquer:
- Wearing gloves and protective clothing (long sleeves, apron, mask)
- Using a mask (especially when sanding the sabi urushi)
- Working in a well-ventilated area
-Regularly changing gloves during prolonged work
- Thorough cleaning of tools and surfaces after use
- Safe disposal of used rags, wipes, and containers
⚠️ Even after hardening, urushi can remain hazardous when sanding. It is essential to wear a filtering mask to avoid inhaling the particles.
Essential safety rules when using urushi lacquer:
- Wearing gloves and protective clothing (long sleeves, apron, mask)
- Using a mask (especially when sanding the sabi)
- Working in a well-ventilated area
- Regularly changing gloves during prolonged work
- Thoroughly cleaning tools and surfaces after use
- Safe disposal of used rags, wipes, and containers
What to do in case of exposure to urushiol:
- First aid :
- Immediately wash the exposed skin with cold water and soap
- Do not scratch the irritated areas to avoid worsening the condition
- Consult a doctor or dermatologist in case of severe reaction
Some people develop partial or full immunity over time after regular contact with small amounts of urushi. However, this tolerance should never replace basic precautions !
Conclusion
Urushi lacquer is a fascinating and valuable material, but it requires careful handling. By following safety rules, you can practice Kintsugi with peace of mind, without risk to your health.
#Urushi #Kintsugi #JapaneseLacquer #RhusDermatitis #Urushiol #JapaneseCraftsmanship #UrushiBox #UrushiProtection
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