Be careful you don’t end up like Barney Fife with the “mange curing” skin cream.
My father was given dilute HCL to drink when he was having some sort of digestive problem back around 1960. It doesn’t appear to be considered much of a hazard at low enough concentrations.
Stomach acid is HCl. We’ve all reverse-drank it at some time or another.
In my college chem class, I was working alongside a classmate under a fume hood, and somehow he flipped a droplet of 18M sulfuric acid so that it landed on my arm. I still have that scar.
Yeah, sulfuric and nitric are both significantly nastier than hydrochloric. Sulfuric is probably better known as “battery acid”; I don’t know if ordinary household users had any reason to have nitric.
Of course, hydrofluoric is much nastier than any of them, despite being only weakly acidic.
Well, concentrated sulfuric is extremely hydrophilic and will literally suck water out of any organic compound leaving carbon. Check YouTube for H2SO4 + sugar. Add some hydrogen peroxide, and you have a very interesting cocktail.
Concentrated hydrochloric is no problem getting on your skin. Rinse it off fairly quickly, and you’ll be fine. Concentrated sulfuric is a little more iffy, but on thick skin you stil have plenty of time to rinse it off before it becomes a problem. Nitric, OTOH, or even worse, hydrofluoric… I stay as far away from those as I can. Particularly hydrofluoric, that stuff is nasty.
The summer after my HS graduation, I worked in a factory. They had online flue gas analyses, but the gas had to be dried before it was fed into the analyzer. They dried the gas by bubbling it through concentrated sulfuric, and one of my tasks was to change the acid. I got the stuff on my fingers more than once, and my work clothes fared much worse than my fingers did…
And, in many dialects, only one phoneme different than hydrochloric acid.
You have to admire an acid that is smart enough to dissolve a barnacle shell you don’t want but leave the seashell you do want intact. That acid might be safe, but it’s much smarter than it is safe. 
Many domain registrars sell a service to anonymize your domain hosting. Mostly so spammers won’t use the ICANN database as a mailing list for every scam there is. The registrar puts themselves out there to ICANN as the registration contact(s) for your domain, and meanwhile if they do get legitimate domain-related contacts they can pass them to your real (private) contact info.
Yowza. Shades of the Chinese selling industrial waste as real products. See
for an example.
But at least you also had some dead muskrats. That’s gotta be of some benefit. 
From the site:
“For difficult-to-clean shells, purchase muriatic acid, tongs, a wire brush, a metal pick, and a glass container.”
and
" 1. If the shell still has growths or large white calcium buildup on it, softly scrub with a wire brush or use a metal pick. I use the small picks found inside dental kits and they work well."
I assume you missed this. Maybe a bit too quick to imply a normal seemingly perfectly honest hobbyist is lying?
The only significant information on the MSDS is that this is re-labelled Enviro-Syn HCR-7000-WL, a product from Fluid Energy Group.
Then Spectrum Sterilization isn’t actually “manufacturing” the stuff.
I wonder if they’re actually involved or it’s just another lie?
Made for cleaning pipes in oil wells. And a Canadian company, so that explains the ferrin gallon size.
It is a fracking fluid. Lots of Google hits for the stuff. Still don’t see one that says what is in it, though.
And here is a skin safety demonstration. But it isn’t brown. Which brings back the idea of it being used fracking fluid…
I wonder if FEG would like to hear about our scammy friend or if there’s anything they can do?
I did. I was also a bit facetious although i suck ath that level uf subtle umor. I apologize if you were misled.
I suggest that perhaps in another direction, removing a barnacle is not a matter of dissolving its shell which would clearly require the magic ability to tell “good shell” from “bad shell”. But rather it’s a matter of dissolving whatever bio-attachment stuff barnacles secrete to attach themselves to substrates. Which glue, fibrous stuff, or both, could easily be imagined as much more carbohydrates susceptible to acid than is calcium carbonate-based shell material itself.
I sent them an email asking if the brown liquid in the video looked like their product (and giving a summary of the discussion).
Interestingly, a guy I knew studied biochemistry and had this brilliant idea that for his PhD he would study the biological glue used by a local form of sea squirt - known as cunjevoi - to attach itself to rock. It is one of the strongest glues known. Unfortunately last I heard his PhD was failing because he couldn’t find any damn solvent that would dissolve the stuff, which made it impossible to study. I lost touch with him so I never heard how it ended but he had all but given up, last I heard.
I don’t know if barnacles use the same or similar glue, but I’m guessing that 3 seconds immersion in HCl (which is all that website recommends) is not going to remove them at all.
Are there that many people who want to clean seashells that there’s a market for a specialty cleaning product?
Beachcombing is big. Where I originally saw the question about the legitimacy of Safe HCl was on a Facebook group for South and North Carolina seashellers that has 72,000 members.