Pigs don't sweat much, so they wallow in the mud to cool off their bodies. So how did the English language expression "sweating like a pig" develop? It's actually a reference to pig iron, which is form of iron smelting:
Link | Photo via Flickr user The Pug Father used under Creative Commons license
When pig iron is originally created from iron ore, the smelter needs to heat the ore to extreme temperatures, and then move the liquid metal into the mold. Until the liquid cools, it can't be safely moved, as the extremely hot metal is liable to spill, burning whatever it comes in contact with.
How does the smelter know when the metal is cool enough to transport? When the "pigs" "sweat." As the metal cools, the air around it reaches the dew point, causing droplets to form on the metal's surface.
Link | Photo via Flickr user The Pug Father used under Creative Commons license
Your entries are usually right on, and this one might be...but I have my doubts.
Anything can condensate moisture from the air, and if a chunk of iron was cool enough (cooler than the air around it) moisture from the air would condensate on it....but no more so than any of the surrounding objects would. The hot pig iron would have to sit a long time and then be observed early in the morning in order for moisture (dew) to form on it. (obviously cool enough to touch)
So why isn't the expression instead "sweating like a stone", or "sweating like a blade of grass in the morning dew", or "sweating like your car windshield-- (parked outside overnight)"?
Sorry to be critical because your blog entries are usually very good, but I think that this one is weak, and needed at least some critical analysis...despite what a Google search might show. It might be that the phrase came from iron...but then again, it doesn't make sense if it did.
Bill
I don't think that chickens sweat that much...
http://grahams-random-ramblings.blogspot.com/2007/08/what-does-sweating-like-pig-mean.html
I don't think that chicken sweats as much as you think it does.
Thanks for your response.
I am a trivia blog fan and amateur fact checker, I look at several blogs each day...but I have to admit that your entries on Neatorama are the best... To all the readers of this, I'm not a shill, I do not know Mr. Farrier and never will, but he is the best, in my opinion. ...giving credit where credit is due.
As for the "sweating like a pig" thing, I'll admit that I cannot find any substantial evidence to negate the blog post. My opinion though is that it's just an illogical saying...for what it's worth.
Bill