Steam burns are extremely serious. The reasons behind this phenomenon are very simple. For starters, steam is a gas, and can quickly seep through cracks or gaps in a persons clothing and immediately access the skin. Secondly, as soon as the steam hits the skin, it automatically “wets” the surface, providing a large surface area that is covered by the hot steam. This allows the gaseous water to condense very rapidly, pumping all of its heat into the skin in just a few seconds. Finally, water has an unusually high “latent heat of vaporization”. Imagine taking a tea kettle and pouring in cold water, placing the kettle over the burner. Say it takes about five minutes for the water to come to a full boil. Well, it takes seven times more energy to go from boiling water to steam, as it takes to go from cold water to boiling water. So, imagine the amount of heat you needed to boil a pan of water (five minutes of strong heating), and then multiply that amount by seven, and that’s how much heat you’ll need to add to completely evaporate the liquid water into steam.
In chemistry, equations normally work in both directions. So, this large amount of “latent heat” that you had to add to completely vaporize the boiling water comes back when the steam is condensed into water. So all of that huge amount of heat is transferred to someones skin when they receive a steam burn, and it’s transferred over a large patch of skin at a very fast rate. These factors combine to make steam burns extremely serious, and researchers are looking for ways to protect high-risk workers (commercial laundries, steamfitters, etc) from these dangerous burns. One method being investigating for its potential application in this area is the production of hydrophobic coatings for clothing.
A hydrophobic surface is one which – as the name implies – does not get along well with water molecules. A classic example is a car windshield. When it rains, water splatters against the windshield and the raindrops spread out, flattening against the surface and coating a large amount of glass with a sheen of water. This happens because the chemical structure of the glass consists of lots of silicon-oxygen bonds, which get along well with water (they’re hydrophilic, or water loving) and so the water droplets are comfortable spreading out a little bit and soaking over the surface. However, if that same windshield is treated with a solution of Rain-X (a commercial silicon product that makes the glass surface hydrophobic), water droplets which fall on the windshield don’t spread out. Instead, they ball up into tight spheres and are quickly whisked off the surface of the glass. Often times, a freshly treated windshield doesn’t even need windshield wipers – the water skims right off, like a ducks back (another example of a hydrophobic surface).
Putting a hydrophobic on clothing is one example of how a person could be protected from a steam burn. There are two factors at play: the shape of water droplets that are motionless on the surface (called static water), and also dynamic water, which is droplets that are sprayed onto the surface. Compounds such as Teflon work well for repelling static water but fail to deliver for dynamic water, which of course is a large component of steam. Therefore, researchers in the UK have settled upon a modification of this method: combining Teflon with carbon nanotubes. They have published their results in the Journal of Materials Chemistry. The carbon nanotubes are microscopic hollow tubes of pure carbon, and they serve to increase the roughness of the fabric surface. This added roughness traps tiny air bubbles in microscopic pores, all over the surface of the fabric, and as a result the Teflon coating can more easily repel high dynamic water pressures. The air trapped in the pores helps to lift off the water molecules and shed them from the surface.
It would take a large leap of faith for anyone to deliberately step into a steam geyser, carbon nanotubes in their jumpsuit or not. However, this modification was shown to have positive results, and the water repelling nature of the surface was enhanced. It remains to be seen if this process can be commercialized, or if more innovation is needed before workers become completely comfortable working around dangerously hot water.