Why does aluminum foil have one shiny side and one with a matte finish?

https://bookofjoe2.blogspot.com/2025/10/why-does-aluminum-foil-have-one-shiny.html

by surprisetalk • 5 months ago

71 51 5 months ago

bookofjoe2.blogspot.com

dnemmers• 5 months ago

“The final rolling is therefore done on a sandwich of two sheets, face to face.”

slau2• 5 months ago

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

mjevans• 5 months ago

The foil is the 'meat' the rollers are the bread.

perilunar4• 5 months ago

An open sandwich can have two layers.

AnthonBerg• 5 months ago

jgwil2• 5 months ago

*Whoever wrote that. The person who wrote is the subject of that phrase, not the object.

qingcharles• 5 months ago

To quote the Blues Brothers, that's a "wish sandwich", when you have two slices of bread and you wish you had some meat.

CLPadvocate• 5 months ago

Yet many people persist in calling aluminum foil "tinfoil."
We chemists get annoyed at things like that.
Now, about aluminum foil.

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

dpe822• 5 months ago

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

st_goliath• 5 months ago

Well, the name Davy originally proposed was alumium.

I propose we switch to that instead, so everyone can be annoyed equally and in the same way.

thomassmith65• 5 months ago

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.

elric• 5 months ago

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.

gethly2• 5 months ago

Try to make them pronounce nuclear instead of nucelar :D

monocasa2• 5 months ago

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.

adrian_b• 5 months ago

The suffix "-io-", which becomes "-ium" in accusative/nominative neuter Latin nouns, is extremely ancient. It is inherited from the common Indo-European language.

This suffix is used to derive nouns or adjectives from other nouns, where the derived nouns are understood to have some kind of relationship with the base nouns.

A great number of the names of chemical elements use the Latin variant of this suffix, i.e. "-ium", to derive the name of the element either from the name of the substance from which it has been extracted, or from the name of some characteristic property of the element or from some mythological name or from some person or place that is intended to be honored by this choice.

The name of aluminium comes from the name of the aluminium sulfate in Latin, which was "alumin-".

So "aluminium" means "something that is not aluminium sulfate, but it is related to aluminium sulfate".

On the other hand, "aluminum", which lacks the derivation suffix, just means "aluminium sulfate" (which has become "alum" in English), but the noun has been converted from the 3rd Latin declension to the 2nd Latin declension. Such conversion between declensions were not unusual even for native Latin speakers.

So this is definitely a grammar mistake, which is annoying for those who understand the meaning of words, because it creates an exception that must be remembered, instead of applying the general rule.

In general the British and American scientists have always been much more lax in observing grammar rules than the continental Europeans. So there are also other chemical elements where the English names differ from the correct names. For instance the name of the chemical element "silicium" is derived from Latin "silic-" (flint), from which it is extracted, but in English it has been changed to "silicon", for the silly reason to make it rhyme with "carbon", despite the fact that most chemical properties of silicon resemble more those of boron or of phosphorus or of germanium, than those of carbon (because valence is only 1 of the 3 main properties that determine chemical behavior, electronegativity and ionic/atomic size are equally important). (Carbon is one of the few elements that were known in pure form already in the Ancient World, so its name is not derived from another noun.) ("Boron" has also been changed in English to make it rhyme with "carbon", which is equally baseless.)

johng• 5 months ago

I always heard the shiny side reflected heat better. So that side should face food you are trying to heat up in the oven.

Any truth to that I wonder?

ahhhhnoooo• 5 months ago

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.

hamstergene• 5 months ago

I can speak for myself: when I ask if the shiny side reflects the heat better, I don't mean to also ask if the difference is significant. It's really just curiosity, whether my school physics intuition holds up or lies to me, that's all.

So, "technically yes" is good enough answer for me.

bob1029• 5 months ago

The only heat that would be different would be radiated heat, which your food won't have a ton of

Your food won't radiate much heat, but your oven certainly does. Aluminum + broiler is like photolithography for food.

sawjet• 5 months ago

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

rocqua• 5 months ago

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

cwillu3• 5 months ago

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.

bmicraft• 5 months ago

Is it? I can see the broiler glowing, so at least a decent chunk is close to visible light.

DerArzt• 5 months ago

microwave or conventional oven

I worry for you if you're microwaving aluminum foil.

rich_sasha• 5 months ago

Which side is better at reflecting woke beams from space?

NewCzech• 5 months ago

People deeply understand the physics of tinfoil hats. A properly constructed tinfoil hat needs two layers, with the shiny sides facing in opposite directions. Only the shiny side reflects brain waves. You need to reflect in both directions: one direction keeps the government from using waves to put ideas in your head; the other is to keep the government from reading your mind.

kombookcha• 5 months ago

For you mindwarriors out there who like to go on the offence, leave a removable fold over your third eye so you can quickly flip it open and be ready to engage in PSI-combat on the astral plane or realspace as the situation requires.

Etheryte• 5 months ago

The study [0] linked at the bottom of the article has good insights on that, plus it's a marvelous read all around.

[0] https://web.archive.org/web/20060612212953/http://people.csa...

red75prime• 5 months ago

Aren't they from somewhat below waist level a parte posteriori?

botusaurus• 5 months ago

so if you skipped the final rolling it would be shiny on both sides?

is this being produced?

jmward01• 5 months ago

I believe 'heavy duty' foil is sold. I don't have any to check but my guess is both sides are shiny. In fact, I think I remember both sides being shiny the last time I used it...

ZeWaka• 5 months ago

It's 3.33x thicker, yes - we use it in foodservice. (0.8mm vs 0.24mm)

gethly2• 5 months ago

aluminium :D

undebuggable• 5 months ago

Shiny side is for wrapping the end of banana, the matte for the other end.

whynotmaybe• 5 months ago

And in French it's often called "papier alu" when there's no trace of paper at all.

bestouff• 5 months ago

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

Why does aluminum foil have one shiny side and one with a matte finish?

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