Why is there no effective alternative to metal salts in antiperspirants?

[jona173]

Metal salts, especially aluminum compounds are used in antiperspirants to prevent sweating. I found out aluminum chloride hexahydrate, which is found in most antiperspirants, undergoes an acid-base reaction with water which causes the proteins to denaturate, thus these proteins are precipitated out as a gel blocking the sweat glands. Additionally, aluminum is able to bind water molecules.

However, I would like to understand the biological and chemical processes in more detail as I am not quite sure why there is no effective alternative to metal salts to prevent sweating. There are many compounds that could undergo an acid-base reaction with water. There are also different metal salts which are able to bind several layers of water.

My specific questions are:

• Which biological and chemical processes underlie the effect of antiperspirants that make metal salts so effective?
• Why are aluminum salts used most commonly?

[studiot]

What other salts are there besides metal salts?

Would you prefer Ammonia?

[Strange]

1 minute ago, studiot said:

What other salts are there besides metal salts?

I think the question is about alternatives to salts.

[jona173]

10 minutes ago, Strange said:

I think the question is about alternatives to salts.

You're correct. 

I want to know which chemical and biological processes occur that make (metal) salts the most effective way to prevent sweating, especially aluminum. 

Edited May 24, 2019 by jona173

[Ken Fabian]

I don't have any idea why they work - but after years of skin rashes in my armpits I switched to using a few drops of white vinegar instead of antiperspirants. Technically speaking it isn't one; it doesn't suppress perspiration, but does prevent unpleasant odors. I surmise that is by suppressing the bacteria responsible.

[jona173]

2 minutes ago, Ken Fabian said:

I don't have any idea why they work - but after years of skin rashes in my armpits I switched to using a few drops of white vinegar instead of antiperspirants. Technically speaking it isn't one; it doesn't suppress perspiration, but does prevent unpleasant odors. I surmise that is by suppressing the bacteria responsible.

Vinegar makes the armpits too acidic for the bacteria on your skin. It has the same effect as a deodorant then. 

[Strange]

Lemon or grapefruit juice might smell nicer than vinegar!

[Ken Fabian]

12 minutes ago, Strange said:

Lemon or grapefruit juice might smell nicer than vinegar!

The vinegar smell dissipates very quickly, but probably lemon juice would work as well. But why would anyone have grapefruit on hand?

[Strange]

30 minutes ago, Ken Fabian said:

But why would anyone have grapefruit on hand?

Because they are delicious?

To stay on topic, citrus fruit might be more effective for longer because acetic acid is volatile (which is why the smell dissipates)

[Ken Fabian]

3 hours ago, Strange said:

Because they are delicious?

I suppose some people think grapefruit are delicious but I am tempted to call you strange for that! Not that I eat lemons, except mixed with other things - perhaps mixed with other things I would like grapefruit too.

3 hours ago, Strange said:

citrus fruit might be more effective for longer because acetic acid is volatile (which is why the smell dissipates)

Only needed perhaps twice a week, so effectiveness is not an issue. More surmising here, that enough bacteria are killed from the acidity to have a lasting affect.

4 hours ago, jona173 said:

• Which biological and chemical processes underlie the effect of antiperspirants that make metal salts so effective?
• Why are aluminum salts used most commonly?

Jona173 - I suspect finding appropriate chemicals was more trial and error than any understanding of the chemistry and physiology of how antiperspirants work. I hadn't realised they cause sweat ducts to be physically blocked. I would have thought sweat would push past a gel blockage. Whether the sweating itself is impeded by the higher pressure or it is reabsorbed by the sweat duct is a question that comes to my mind next - and those would be different for eccrine sweat glands and apocrine. And I wonder whether that is a potential trigger for skin irritation.

Edited May 25, 2019 by Ken Fabian