Readers reply: Is there a liquid wetter than water?

Is there a liquid wetter than water? Kathy Wight, Portsmouth

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Readers reply The word wet comes from the Old English wæt and is ultimately related to the word water. Wet was originally used in its literal sense of "not dry", but it took on many metaphorical extensions over the centuries. By the middle of the 15th century, wet meant to get drunk. By the late 17th century, wet surfaced as a noun in the phrase "take a wet", or have a drink. By the early 1700s, a wet person was a drunk one. Consequently, I would say beer is wetter than water – and the more beer you drink, the wetter it becomes. just_a_thought

Water itself can be split into categories that behave differently, certainly in the amount of damaged caused by wetting. Salt water for instance is considered more damaging and thus is described as having a higher "wetting potential". Sea spray or ocean surge has a higher wetting potential than heavy rain damage. Of course, pollutants will also affect wetting potential, but polluted water, unlike fresh or salt water, is not seen as being water in a natural state – however common it might be in our industrial landscape. woodworm20

The horizontal rain in the west of Ireland is the wettest substance on Earth. That stuff gets your bones wet.

You could argue that most common liquids are wetter than water. Wetting is usually measured by the extent to which a liquid spreads across a surface. Most liquids, especially those with a low surface tension, such as ethanol (alcohol) or even soapy water, spread out more readily over the same surfaces, so (at least in this sense) could be said to be wetter than water. Richard Thompson

I think water is unsurpassed in terms of sogginess, ie the ability to keep something wet for ages. There are liquids that are able to permeate materials better than water, but they usually evaporate quickly, leaving a dry material. Water soaks into things and stays there.

The balance between adhesive and cohesive forces determines the degree of wetting . Cohesive forces, such as hydrogen bonds, hold water molecules to each other and create a surface tension. With strong cohesive forces, water tends to stay as spherical droplets to minimise contact with a surface. Adhesive forces attract the water to the surface of another material and encourage it to spread. If the adhesive forces are stronger than the cohesive ones, then a surface will become wet. Other liquids – such as alcohol – are better than water at wetting. Adding detergents can improve water's wetting ability by lowering the cohesive forces.

Strictly speaking, water isn't wet – it makes other things wet (this is believed to be due to its high moisture content).

If by "wet" you mean "having a tendency to cover a surface with a film of the same liquid" (which is what most people mean when they say something is wet), superfluid liquid helium probably holds the supreme position. With zero viscosity, it will spread over any surface it comes into contact with. That includes escaping over the sides of any container you put it in.

Tea without a biscuit.

Water containing a surfactant .

Adding a bit of detergent to water makes it wet oily surfaces better. But if you want a liquid that just charges through most barriers, then the organic solvent tetrahydrofuran (THF) is pretty impressive. I once worked with the related solvent tetrahydrothiophene (THT) wearing the wrong gloves (most gloves can't protect against these solvents) and absorbed a considerable amount into my hand. THT is not especially toxic, but unlike THF it has a lingering odour far worse than a skunk. Do not get it on your hands ...