Never used walnut dye on clothing, (not intentionally anyway) :idunno:
I did my traps every year before the season. I would throw them into a #2 washtub and put in a handful of walnuts.
The green ones, (that fell before they were ready)or the outer green hull that falls from the nut as the nut does its final ripening, are best to use. I always picked up as much of that outer hull as they fell that I could find. That has the strongest dye in it!
Put it all together in a the wash tub and bring it too a rolling boil. It would dye the traps a dark brown or almost black, but the real reason I started doing it was I found out it would keep the trap from rusting even when used underwater in a water set! It has to do with the tanic acids reaction to the metal in the walnut hull.
As for clothing any spill or intentional dip is pretty much permanent but the act of boiling a garment will probably lead to shrinkage! :rotf: