Jim, I suspect that the scratch and vinegar treatment acts mechanically the
same as the sandpaper/pot scrubber and strong alkaline soap. The surfactant
effect of soap and vinegar probably act similarly. Urushiol, the active
allergen, is a mixture of nonvolatile hydrocarbons (oil) and is probably
emulsified or saponified by the alkalinity or acidity of soap or acetic
acid. May be magical chemistry buffering or neutralization but I doubt it.
As another off-topic note, some people respond to laquerware from the sap of
the Asiatic Lacquer Tree, another member of the Rhus family.
Doc
"Doc,
I sent this to Tanis privately when, it seems I should have sent it to
the group:
Tanis,
When I get poison Ivy, I dip my fingers into vinegar, then using those
vinegary fingers, I scratch the blisters open. Follow that by rubbing in
some more vinegar and the rash begins healing immediately.