Thanks for that input @KenCitron - we have 3 ultrasonic cleaners here, for various purposes… I will investigate. Failing suitability of those 3, I guess that’s another thing to put on my ‘splurge’ list 
!
This would probably explain why I am getting ‘thick’ walls (see my post Calibration Part III)… I definitely notice slippery surfaces and the need to always post-cure the parts to avoid tackiness; in addition, I find the surfaces often need a gentle rubbing with gloved finger to make sure there are no tiny particles on the surface - a soft toothbrush leaves scars (perhaps a very soft artist’s brush is the way to go), and even strong agitation in the IPA bath doesn’t get these all off, so I guess the bath is simply not removing all raw resin either.
@KenCitron : do you print large, thin parts, where warping seems to be most common? As soon as I get to complex parts with 2-3mm or thicker walls, I don’t have a problem… but print a panel at under 3mm and bingo, I get warpage, even if I keep the IPA bath short, like 3-4 minutes of shaking and then that’s it.