[NaOH]

How concentrate is it? How corrosive to materials and skin is it?

[nj_bartel]

37% (as concentrated as you can make HCl in water under standard conditions).  Generally, very.

[skyjumper]

32% (The Muriatic acid from Aubuchan Hardware (http://paint-and-supplies.hardwarestore.com/50-270-concrete-cleaners/muriatic-acid-605183.aspx?utm_source=google&utm_medium=cpc&utm_term=605183&utm_campaign=googlebase) says it is 20 baume and wikipedia says 32% HCl is 20 baume.

As for the other question, anything above 25% is classified as corrosive

[Borek]

Define corrosive quantitatively.

[khemikuhlz]

Ace Hardware, many paint stores, Lowes, and some others sell Muriatic acid at 31.45%
The remaining percentage is comprised of inert ingredients or so it says.
What and how inert the ingredients are is what I'd like to know.

And I would say that a definition of corrosive depends as much on the material to be (or not to be) corroded as it does on the corroding (or not corroding as it were) substance. 

[billnotgatez]

is there not a MSDS standard definition of corrosive

[skyjumper]

the "inert" ingredient is water

[khemikuhlz]

Are you sure about that?
How can we be sure that the inert ingredient is water?

[skyjumper]

I suppose they could have added some kind of a buffer as well...

[Borek]

What kind of a buffer, and what for? To keep pH constant? In concentrated strong acid?

Are you sure about that?
How can we be sure that the inert ingredient is water?

There are not many other options. And when you think about economics - there are NO other options.

Doesn't mean acid is not contaminated with small amounts of other substances, but that's another problem.

[billnotgatez]

The container of sulfuric acid drain unclogger I saw said buffered - never did find out what that meant.

Maybe they put stuff in to foil other uses - sort of like denature ethanol.

[khemikuhlz]

Those wascally wabbits...

Could these acids be distilled in a closed system to purify?

[skyjumper]

I saw a video on getting reagent grade Hcl from store bought... Leme find it

http://www.youtube.com/user/TheHomeScientist?blend=2&ob=1#p/u/17/jv1Ms6Subg4