This is a card made with some lemon juice heated till it turned color.
I swiped some lemon juice on white paper with an old toothbrush,
but you can use a paintbrush or a sponge, any means to apply.
After swiping some juice on my paper I heated it until it began to turn dark.
The longer you heat it, the darker it gets.
I stamped the image by Hero Arts amd matted it then layered that over some wispy paper with
a die-cut flourish as an embellishment.