Creating stronger materials may be as simple as adding melanin, the molecule that lends skin its pigment and protects animals from ultraviolet rays.

In recent experiments, scientists found a small addition of melanin made polyurethane much stronger. Researchers described their findings in the journal Biomacromolecules.

Polyurethane mostly comes in the form of high-resistance foam, used most commonly for seating and insulation. But the material is used to enhance a variety of products, from epoxies to clothes.

Materials scientists have traded a range of additives and fillers in an attempt to bolster polyurethane, but gains have been modest and often isolated to singular physical qualities -- improving either tensile strength or toughness, but not both.

A material's tensile strength is its resistance to breaking under tension. Toughness describes a material's ability to absorb energy without breaking.

Experiments showed polyurethane samples containing just 2 percent melanin -- sourced from the ink sacs of cuttlefish -- were tougher and more resistant to tension than control materials.