Tiny cracks can actually be a big deal when they're forming inside parts of your car or, say, a metal shell that's flying into space. University of Illinois research, led by Professors Nancy Sottos and Scott White, has lead to a polymer coating that could be an important early warning system, making it easier to find trouble spots before something really bad happens. When cracks form in the polymer, micro-beads also crack open, causing a chemical reaction that visibly highlights the damage with color. The capsules are pH sensitive, meaning any damage will cause a strong color change, from yellow to red, with no additional chemicals needed. Deeper, more serious, scratches and damage will create stronger hues of red as more capsules break open.