For cleanup, as you state, it is an oil so soaps that are good at cutting oil seem to work well: Dawn, Go-Jo, etc. I would stay away from any shop type soaps that have pumice or similar sandy scrubbing components as abrading your skin isn’t advisable when it’s covered in poisonous oil. Along those same lines, use cold water to wash yourself, even if you’re taking a full shower. Hot water opens your pores and aids in allowing the oil to penetrate your skin. Washing with a non-abrasive Go-Jo in cold water works best for me. After you’ve washed the oil off, you can go back to hot water washing and showering.
Wash all clothing and surfaces that may have been exposed. They will retain the oil for quite some time so you can be re-exposed every time you touch them. Worst case I ever had was due to getting it all over the armrest in my truck. Kept getting worse for over a month until I figured it out and shampooed the armrest. If I thought it was inside my gloves I would replace them.
What to do about the flared up areas... Do not scratch. Scratching just further damages your skin and extends healing time. Apply cortisone and/or astringent such as witch hazel to minimize itching and oozing. If you tend to scratch in your sleep or are short on self control, cover it. Wait it out. I haven’t found anything that truly shortens recovery other than thoroughly cleaning myself, cleaning all potentially contaminated items, and not scratching.
If it’s REALLY bad, a doctor can give you a cortisone shot that will dry it up, but it will dry up everything, including your sinuses, nose, mouth, and gut (as in some bad constipation). Personally, I’d rather itch and poop on schedule.
Interested to see if anyone else has a better way of shortening the recovery.
Never heard of tehcnu, sounds like some sort of car wax to me.