Dip shirt in liquid with boiling point lower than water. Re-wet as necessary.

Or weave sealed cells of a phase-change material with high thermal mass that melts at around 33 degC into your fabric, and freeze the garment before wearing it. This makes possible a thick, heavy jacket that you can wear to keep cool.

Are you suggesting that someone should wear a wet shirt so that they can stay warm? Or wear an ice cube to stay cool? I guess I'm missing the joke?

The intention, I imagine, was that the wet shirt keeps you cool by evaporative cooling.

Yes, exactly.

I suppose the vapor pressure could be lower than that for water, if there were effectively none in the air already. That would only be more effective than sweat on very humid days. You would be wetting your wet bulb with two different liquids.

The trick is to find one better than water that is also non-toxic, non-flammable, non-carcinogenic, and non-polluting. It would almost be easier to just remove all that water from the surrounding humid air, so that sweating works to cool you down again....

The phase-change material between liquid and solid would work better, but still requires a separate cooling technology to "recharge" it. And phase-change material still works better in building walls than in clothing. So you're right back to keeping your whole building cool, rather than a specific person.

You could also strap a personal radiator to your back, but no one wants to work on the tropical plantation in the first place, much less do it inside spacesuit-like apparel.

> Dip shirt in liquid with boiling point lower than water. Re-wet as necessary.

Can you recommend one suitable for regular use?

Ethyl alcohol is cheap, highly available; people are already familiar with its particular flammability and toxicity issues and are comfortable handling it.

You would not only get very drunk from that, you could damage your skin and/or catch fire, if there is a source of ignition.

There are a few liquids that would work. One example is the refrigerant HCFC-124. However, all of these liquids are chlorofluorocarbons, and cause much more damage to the atmosphere than any amount of A/C usage. Pretty much all volatile organic compounds fall into at least one of three categories: flammable, toxic, highly potent greenhouse gas.

Don't forget carcinogenic, teratogenic, corrosive, unbearably stinky, and insect pheromone.

For instance, you wouldn't want to smell like a ton of bananas all the time, or drive honeybees into a frenzy every time you pass by.

I'm comfortable pouring diluted alcohol in a glass and drinking it, not with soaking my clothes in it and covering large areas of my body in a continual bath of flammable liquid that also dries out my skin.