Why does aluminum foil have one shiny side and one with a matte finish? (bookofjoe2.blogspot.com)

Whomever wrote that clearly has never made or eaten a sandwich. Without something in between the two layers, it’s hardly a sandwich.

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Sir Humphry Davy first isolated the stuff and he called it aluminum, so that's good enough for me.

It isn't clear if that is a dig at Americans having their own spelling of aluminum/aluminium, or ignorance that Americans have their own spelling.

> Actually, most chemists are profoundly annoyed at the Americans' inability to spell aluminium properly...

That's just patently false. Anyone who's had any sort of education in chemistry/physics is aware of the history of the word and doesn't give a damn.

Try to make them pronounce nuclear instead of nucelar :D

Humphrey Davy, the British chemist who performed early work to isolate the element, and who initially named it, called it 'aluminum'. Americans mostly followed him, but the British changed later at the complaints of the French, Swedish, and Germans that it used essentially English roots rather than Latin ones. Which, considering that we now have elements named such things as Tennessine, seems to be a bit of an argument that doesn't quite apply anymore.

No. Aluminum foil has the same material properties with respect to convection and conduction of heat no matter which side faces out. The only heat that would be different would be radiated heat, which your food won't have a ton of, and even then, the dull side is still quite reflective. It's maybe one of those "technically" correct statements that the shiny side reflects more heat, but for the application of cooking, the impact is effectively zero. The retention of steam is going to be such a larger factor the side you use will effectively make no difference.

The shiny and dull sides look like perfect mirrors in IR wavelengths.

I recall similar advice around mylar heat blankets. Perhaps those got mixed up?

The feature size of the matte vs shiny sides are much smaller than the wavelength of the bulk of the radiated light in either a microwave or conventional oven.

Like an e-ink (or e-paper) screen