Repeating Rifle writes:
This time, after washing away the color, I went back out and handled the
tomato plants some more. Hand washing brought out the yellow color again.

Is this typical of tomatoes? What is the substance involved?

Nature frequently provides its own "antidote". Squash a rotten (i.e.,
waste overripe) tomato and lather your hands thoroughly with the mess.
The yellow stain comes off your hands then without the need for much soap
when you rinse.

I seem to recall nature providing an antidote for mulberry stain, and
for stinging nettles, too. I think you squash some of the red fruit (i.e.,
the unripe ones) to remove from your hands the stain that the black
mulberries cause.
--
John Savage (my news address is not valid for email)