I've so far handled only concentrated fuming nitric, sulfuric & hydrochloric acids from the inorganic side. Even during an accidental spill on the hand I did say only the $\ce{HNO3}$ affects the skin by turning it yellow and the top layer sometimes peels off.

But in the organic acid side I've had once experience in the past long long ago with formic acid and it was pretty nasty. A really pungent smell and if it gets on the hand then immediately the top layer of skin will peel off. Worse than there inorganic ones. Is 99.8% acetic acid this strong?

I'm about to prepare some homemade stop bath solution for Black and White film development. I'm going to prepare a 10% acetic acid solution. Just wanted to know though I will wear nitrile gloves, in case a few drops come on the skin how bad will it be? I can't seem to find any video or much info of it's effect on YouTube or anywhere either? Just want to take all precautions.

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    $\begingroup$ It's not so bad as formic, afaik. Pure acetic acid is glacial, though. $\endgroup$ – Mithoron Feb 18 at 20:17
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    $\begingroup$ Glacial acetic acid will cause a nasty burn. It might not be as bad as formic acid, but it took most of the skin off my right hand. $\endgroup$ – MaxW Feb 18 at 20:33
  • $\begingroup$ @MaxW Yikes! Thanks for the info. I never though acetic acid would be that bad. Well again the oner I've is glacial. I read some people mention it's flammable too. Does it catch fire when near a flame? IS that what people mean or is it because it reacts with metals to produce H2 gas? $\endgroup$ – The_Vintage_Collector Feb 18 at 22:07
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    $\begingroup$ Safety data sheets for chemicals exist for a reason. Read what the sheet says about glacial acetic acid (and worry about the vapour as well as the liquid: it is pungent and dangerous if you breathe it). $\endgroup$ – matt_black Feb 19 at 11:17
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    $\begingroup$ @The_Vintage_Collector If you're going to be playing with chemicals you really need to educate yourself on basic lab safety. One critical part of that is learn about safety data sheets (SDSs) - every chemical that can be bought or sold must have one and you must get into the habit of reading the SDS before you even think about opening a chemical you are not familiar with. It tells you everything that is known and not known about a chemical's properties, hazards, and safe handling requirements. Don't trust internet people - read the SDS. $\endgroup$ – J... Feb 19 at 18:34

Yes it is corrosive to skin. The Safety Data Sheet identifies it as Category 1A for skin corrosion, which means:

A substance that, according to animal data acquired from a scientifically validated method, produces irreversible damage to the skin after an exposure of three minutes or less, and within one hour of observation, in at least one of three animals.

Don't let the "organic" part fool you. In terms of handling hazards glacial acetic acid rivals concentrated hydrochloric acid, and actually beats it in skin corrosion classification.

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    $\begingroup$ I hurt my hand about 1971. Long before any sort of protective gloves were common. What I was doing was setting up the reagents for the experiment where acetic acid and ethanol form an ester. Being an idiot I thought glacial acetic acid was just like vinegar. $\endgroup$ – MaxW Feb 19 at 4:50
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    $\begingroup$ Oscar Lanzi & @MaxW This is what happened with me when I was like 15 years old when I handled Formic acid. I managed to prepare the solution and used some special gloves used to handle acids and other corrosive liquids when handling them. $\endgroup$ – The_Vintage_Collector Feb 19 at 13:50

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