But on a recent winter afternoon Yasin's younger sibling was himself toiling over a vat of indigo dye in which the water hasn't been changed in a generation.
Unlike oil, the dye has the same density as the surrounding water, does not coagulate or form slicks, and is not subject to chemical breakdown by bacteria or other forces.
To solve this problem, the researchers at the Max Planck Institute developed a technique using a fluorescent dye to make the spinal cord transparent, replacing the water that is normally there.