# Why does muriatic acid turn your skin brown **URL:** \ **Category:** Factual Questions\ **Created:** [March 18, 2015, 3:08pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295 "2015-03-18T15:08:27Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [March 18, 2015, 3:08pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/1 "2015-03-18T15:08:27Z")
As I was reading [this thread](http://boards.straightdope.com/sdmb/showthread.php?t=751944)and someone mentioned muriatic acid, I took a trip down memory lane. After my freshman year in college, I worked in the maintenance department for a water treatment plant. The plant had a big lime silo. One time, the box where the lime comes out of the silo got all caked up. I was told to go to the store, buy some muriatic acid and use it to get all the lime gunk off. I was working with another guy. He didn’t wear gloves and so I didn’t either. The acid worked great. The next day (or sometime later, I don’t remember clearly) some of the skin on my hands turned brown from where the acid touched them\*. It never hurt. I never felt a thing. Why does it do this? What makes it brown? How much damage was done to my skin? \*The other guy was black so I don’t even know if he noticed this effect. ---
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [March 19, 2015, 1:26pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/2 "2015-03-19T13:26:37Z")
Wow, I did not expect silence on this one. No one else has had similar experiences? Maybe the combination of the lime and acid was the source of the brown. ---
**Author:** ![Dorjan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dorjan/32/12440_2.png) [@Dorjan](https://boards.straightdope.com/u/Dorjan)\ **Post date:** [March 19, 2015, 2:02pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/3 "2015-03-19T14:02:38Z")
It’s a chemical burn. They don’t always hurt, or show up right away. Color and effects vary widely depending on the substance involved. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [March 19, 2015, 2:26pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/4 "2015-03-19T14:26:36Z")
I was curious about this also. All I know is that hydrochloric acid is relatively weak and attacks tissue slowly. It sounds more like a stain than a burn. ---
**Author:** ![Kenm](https://avatars.discourse-cdn.com/v4/letter/k/bc79bd/32.png) [@Kenm](https://boards.straightdope.com/u/Kenm)\ **Post date:** [March 19, 2015, 2:31pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/5 "2015-03-19T14:31:52Z")
Muriatic acid is [**less pure hydrochloric acid**](https://www.google.co.uk/search?as_q=%22muriatic+acid%22+%22hydrochloric+acid%22&as_epq=&as_oq=&as_eq=&as_nlo=&as_nhi=&lr=&cr=&as_qdr=all&as_sitesearch=&as_occt=any&safe=images&tbs=&as_filetype=&as_rights=), so I ran a search using that name and found, among many other hits, this [**this article**](http://www.ncbi.nlm.nih.gov/pubmed/19269213) about a man discovered in a tank of the stuff. > [@](#): > > These findings suggest that chemical burn by hydrochloric acid results in a change of skin color due to chemical reaction so that the appearance of the chemical burn is more severe than the degree assigned by histological examination. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [March 19, 2015, 2:36pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/6 "2015-03-19T14:36:02Z")
the chemical burn killing some skin. other acids can do similar. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 19, 2015, 2:50pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/7 "2015-03-19T14:50:35Z")
I’ve gotten HCl on me plenty of times and never experienced this. Maybe it oxidized some metal and the salts stained the skin. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [March 19, 2015, 5:02pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/8 "2015-03-19T17:02:28Z")
I’m with \*\*Ruken \*\* on this one, I’ve never seen it happen. Nitric acid, that leaves brown stains, I used to get them all the time doing digestions for metals analysis. Never thought about the mechanism. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [March 19, 2015, 8:00pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/9 "2015-03-19T20:00:10Z")
All right, I looked it up. According to Wikipedia nitric acid leaves stains because Xanthoproteic acid is formed when the acid contacts epithelial cells and is indicative of inadequate safety precautions when handling nitric acid. I remember them as being brown, but Wiki says yellow. Anyway, stains from nitric I remember, but not hydrochloric. ---
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [March 19, 2015, 9:59pm UTC](https://boards.straightdope.com/t/why-does-muriatic-acid-turn-your-skin-brown/715295/10 "2015-03-19T21:59:39Z")
Thanks for the responses guys. I am not exactly sure. I know it wasn’t Nitric acid because I wouldn’t have a flying clue where to even get that. Maybe it was something in the lime that did it.