Poison Ivy question.?

My dad seems to think that MEK (methyl ethyl ketone) will stop his poison ivy itch. I am of the opinion that mineral spirits will work better for getting rid of the urushiol itch. Or are we both wrong. Our thinking is that urushiol is an oil, and even though it has already bonded to his skin, should not the MEK or spirits "cut" it off and stop the itch.