A Wetsuit for All Seasons

The U.S. Navy is working on a unique way to keep its divers warm — a layer of foam containing bits of wax inside tiny plastic beads, each just a tenth the width of a human hair. These bits of wax melt and freeze as the temperature changes. While the diver is putting on the drysuit, the wax absorbs warmth from the diver’s body and melts. Then, when the diver slips into the icy waters, the wax freezes, radiating latent heat back to the diver.

To provide optimal warmth to the diver, the wax must melt at a temperature below that of bare skin — about 92° F. Similarly, the wax must freeze at temperatures as high as 65° F. to provide enough heat to the diver.

So far, the warming effect lasts for about the first half an hour or so of the dive. However, the Navy hopes to improve on that by packing more of the wax into the diving suit liner or weaving the beads into layers of synthetic fabric instead of foam. Another way to extend the warming capacity could be using a combination of waxes that freeze at different temperatures, so that heat is released gradually as the temperature drops.

The beads, which look like fine dust, can be placed inside fabric fibers by mixing them with the liquid polymers used to make artificial fibers.

Catherine Zandonella, New Scientist