It's funny. The one time I used the stuff, I was wearing nothing more than my garage / yard work / wrenching clothes. Made me cough a bit too.
So if spraying on aluminum, what's "too long"? The directions state to leave it on for 15min before spraying down with water. Would 15min be "too long" for aluminum?
Most people do the same thing; it's "Totally Safe" until it's not.
Anything caustic is dangerous; you get it in your eye, it's a permanent problem.
Following the directions is usually safe, but PPE is a good idea for any strong cleaner; heck, for example, Formula 409 is specifically designed to dissolve dead human skin, as that's 90% of what dirt and dust around the house actually is. :O
I use a much stronger alkali (Sodium Hydroxide) to clean condenser coils, so it should be fine for that
You just need to be careful using strong products for the wrong use.
Mag wheel cleaner that has Hydrofluoric acid works great on getting organic material off aluminum, but it's dangerous as fuck, and the bottle just says basically "don't get this on you".
I used that to clean all my aluminum parts on my engine. Made the driveway nice and clean too. (concrete neutralizes the acid, so it's ok for the environment.)
For removable covers and such, soda blasting works great, and paint sticks like crazy; just make sure to wash it off carefully after.
My mom cleared the house a couple of times with chlorine fumes before I noticed the stainless sink was rusted; she was pouring drain cleaner into the drain, then following it up with bleach.
When I replaced the Iron drains with PVC, they were iron foil.
(Drains were leaking for some reason...)
This releases clouds of noxious Chlorine gas, so don't do that. (Any acid with bleach will do this.)
Chlorine will rust almost any metal.
Any strong acid or base will cause bimetallic corrosion, like salt, but much faster.
For example, Baking soda will eat holes in aluminum, but it's safe to bathe in, and drink for a tummyache, so...
Chemistry is a good class to take.
As far as PPE; Hydrofluoric acid or Roundup will not cause any problem at all if you get it on your skin until Much later,when it eats your bones or kills your heart (HF), or kills you with Lymphoma (Roundup); We're pretty sure that's what killed my Grandma and Mom (roundup).
They never used even gloves, because it was "Safe".
Just because it doesn't kill you today doesn't mean it's OK; be careful.
I use a lot of chemicals in ways not intended; so I am aware of the dangers involved.
Safety goggles that will prevent a splash are Really Necessary for any strong chemical like this; a running hose will not wash this out of your eyes fast enough to prevent you from serious eye damage.
Especially Acids and strong bases (Alkali).
Drain cleaner (H2SO4), coil cleaner (NaOH), Mag wheel cleaner (HF and HClO4), and driveway cleaner (HCl) are the strongest things out there.
And think of the kids... They have no concept of danger.
"Look how this freaks out when I pour them together!"
And never get uncured Urethane on your skin; it sensitizes the first time, (like poison ivy) then later a small exposure can cause you to breakout all over with Hives; kinda like poison ivy on steroids, lol.
Breathing uncured urethane spray or uncured sanded dust will kill lung tissue on contact, so I wear a respirator working with it. Urethanes are Cyanide based.
A coworker broke out multiple times before I finally felt sorry for him, and clued him in. He was an idiot, and somewhat deserved it, so I waited a few times, lol. I can't imagine how much that must have itched.