AN ARTIFICIAL version of the buttery coating that protects and nurtures a fetus’s developing skin could find a use outside the womb, in speeding up wound healing and treating eczema.

Natural vernix caseosa contains a mixture of fatty compounds that waterproof the fetus. Crucially, it also contains dead cells called corneocytes, which store large amounts of water and ensure that the fetus does not get dehydrated. Vernix may also act as a barrier to infections.

To mimic this versatile substance, Joke Bouwstra and Robert Rissman at Leiden University in the Netherlands mixed a range of fatty compounds including lanolin, fatty …