This is my first time using this site and i'm excited to get answers to roadblocks that have prevented me from finishing my writing in the past. However, you may have to excuse some mistakes I make along the way, internet communication isn't exactly my forte.

For starters, I've been trying to develop a character whose skin is not only immune to burning via acid, but also has a seemingly infinite supply of acid withing herself which she secretes all over her body uncontrollably. My questions are as follows:

  • What type of acid should she secrete? I know hydrochloric acid is in our stomachs but that's not strong enough, it needs to be able to burn through skin and metal (kinda like alien, I guess). Some light research introduced to me hydrofluoric acid and fluoroantimonic acid, but I don't know enough about acids.

  • Where does she store the acid inside her body and how does she get it out? It's possible she could store it in her stomach and it could come out her pores but I'm open to plenty of other ideas, because mine doesn't make a whole lot of sense.

  • Finally, what could she wear to protect the things she comes in contact with? At first I was thinking thick rubber but then I came across Teflon, a material that apparently stops acid, but again I really have no idea.

I hope my questions are easy enough to answer. If you can think of any other problems with my character you would like to answer, then feel free. Your help is much appreciated.


  • 3
    $\begingroup$ Two questions. 1) Are you fixed on the idea of it being an acid. There are many other nasty kinds of compounds which don't fit the definition of an "acid". Many of them would be informally called "an acid" by a layman, but are not actually acidic by the chemistry definition. 2) How hung up are you on "any type of metal?" There are many acid-resistant metals, and they'll substantially limit your acid choices. $\endgroup$
    – Cort Ammon
    Aug 30, 2018 at 1:58
  • 3
    $\begingroup$ This sounds like a comic book character. Just go with fluoroantimonic acid (the most powerful acid known to man!) and worry about where she stores it as much as we worry about how Superman flies or where Iron Man stores rocket fuel. $\endgroup$
    – RonJohn
    Aug 30, 2018 at 2:40
  • 1
    $\begingroup$ @RonJohn But technically, Iron man (MCU) uses a imaginary technology called repulsors that convert energy into thrust to fly, powered by the Arc reactor in his chest. Who needs science when you can make up imaginary technology that does that you want? $\endgroup$
    – Shadowzee
    Aug 30, 2018 at 6:18
  • $\begingroup$ The title or your question and the questions contained in its body do not match. I am inclined to see this question, as it is now, too broad. Can you narrow it down and make it more specific? $\endgroup$
    – L.Dutch
    Aug 30, 2018 at 7:03
  • $\begingroup$ @Shadowzee point taken. So I replace it with "*or why Iron Man's feet didn't burn off the first time he tried it, or why he doesn't die of heat stroke inside the suit." $\endgroup$
    – RonJohn
    Aug 30, 2018 at 12:32

2 Answers 2


Teflon is your best bet for what could make her skin acid proof, but honestly hydrochloric acid is your best bet, unless you wanted her to violently react with water, which is what most of the stronger acids do. Be advised though, that without aqua Regina you will almost certainly be unable to corrode gold, and possible platinum as well. But Aqua Regina doesn't dissolve other commoner metals, so you'd need a combo.

Trifluoromethanesulfonic acid seems like a good candidate as well, seeing how its so strong.

  • 1
    $\begingroup$ Aqua regia, royal water, not "regina". Regia means royal (nom. sg. fem.), from rex, reg-is, king. Regina means queen, literally she-king. $\endgroup$
    – AlexP
    Aug 30, 2018 at 16:25

Disclosure: I'm a Chemist, not a biologist.

One of the harder parts of acids is that a lot of them are too harsh for biology, so it's challenging to have an organism use them offensively without hurting itself. You can basically rule out every -fluoric acid, they're way too strong for biology to still function.

The -chloric acid approach is reasonable - Hydrochloric Acid is common in humans at a low strength (<0.8 Molar) or (< 0.8 grams/Liter). Assuming you can purify it biologically with inorganic salts somehow (or some handwavology) , you'll be able to dissolve some metals pretty well at 6-7Molar. HCl gets azeotropic at around 13 Molar, so you likely won't be able to get beyond that. Furthermore, you can make aqua regia: a mixture of Hydrochloric Acid and Nitric Acid (HNO3) which is what I use to chemically purge Nickle from contaminated surfaces in lab research. It's so nasty that we use it only in a ventilation hood with a splash/blast shield, no exposed skin, and never more than 100mL. It'll get the corrosive job done. The body can store it in the stomach just fine (assuming you have stronger mucus to contain it), and pipe it out to pores with dedicated vasculature.

While Teflon is an effective anti-acid polymer, it has to be coated on most surfaces, and its got a LOT of fluorine in it. You breathe in teflon while it's being applied, it will kill you. The mutant is better off wearing protective rubber gloves to contain its corrosives. For its own protection: another solution would be to have your mutant constantly secrete a oily non-polar mucus that would both hydrate its skin and protect it from the strong acids it has. Most mucus is alkaline anyways, so you have a biological basis for it.


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