Every Cashew has a Silver Lining
You are correct about the potency of the urushiol oils in the cashew nut shell. The web is full of laments from past victims who, like my experience with the stinging nettle several decades ago, only need to be bitten once to know never to try it again.
I too had been stung by cashew urushiol oil but, believe it or not, I willingly paid (by credit card) for that privilege.
Let me elaborate.
I am a Kiwi and was on a flight to Kuala Lumpur some years back when I saw an advertisement in the airline magazine about a skin treatment. It talked about the ability of a cashew extract to burn off blemishes on skin. Always game for something new, a few days after landing in KL I made a bee line to the clinic. There I was met by white-cloaked ladies who convinced me that some cosmetic flaws on parts of my body could be easily cleaned up with one or two treatments with this cashew nut oil.
One of these ladies simply used a cotton bud to dab the oil lightly on my unwanted derma protuberances. And as all the victims of accidental urushiol oil ingestion will attest, this potion had a sting to it. The clinic however must have formulated the strength of the oil to a level which was just tolerable.
Within a few days the skin blemishes had started to dry up and soon fell off.
I only had a small part of my skin treated as I didn’t trust the efficacy of the technology at that time and it was rather expensive. It did prove that the cashew can possibly have a place in helping to rescue dermatological disasters but my belief is that it works no better than administering any irritant onto your skin. The skin reacts by self-immolation and then eventually drops off.
The moral of the story is that every cloud has a silver lining. The lining of the cashew nut certainly helps some people to earn a lot of silver.