Bad moments in dyeing

My friend Marti works with dyes all the time and usually batches her fabrics under an electric blanket, as do countless dyers around the world.  That's one of the time-tested methods of keeping the dyes warm enough while they react with the fabric.

But she had never come up with this result before:

The swooping curves follow the electrical wires in the blanket, and the dye was apparently so sensitive to heat that it struck the instant the blanket heated up.

Not at all what she had in mind.