T-Shirt Tomfoolery

[Bob in a quantum-state-of-faith]

Flourine compounds are used in metallurgical processes, and I have myself operated trains that had tanker wagons loaded with hydroflouric acid (unknown concentration, though). I wonder what they were lined with, but I was not inclined to have a look. 

Once, back in the day, I had in my hand a bottle of high molar Hydrofluoric acid.   It was unopened, and had likely been manufactured in the late 50's.  This was in the spring of 1976, and the bottle in question had been inherited to our high school from another, older school that had been closed.   

I was, at the time, the chemistry teacher's assistant for that hour, and was unpacking the boxes of inherited stuff.

Mr Barnard, my teacher, in a very calm voice, cautioned me to take great care with that antique bottle-- as it was made entirely of acid proof wax!   And, if the label was genuine and at all accurate?  There was sufficient 'chemical power' to dissolve my hand....  I carefully placed the bottle (it was an opaque green color) on the counter top....

Mr Barnard was like that-- he did not permit himself to become flustered, and possibly make matters worse...

Now that modern chemistry has discovered high-density polyethylene and high-density polypropylene?  Those antique all-wax bottles are a thing of the past-- pretty much no chemical attacks either of the poly's I mentioned.   About the only thing that does, is ozone or ultra-violet light, and that takes 10's of years or more...

So I quite imagine the liners for your tanks were either of those poly-plastics.  They've long since proved more than resistant to acids of all types.

I suppose there may be an oil- or benzene- based solvent that could slowly degrade the stuff-- but nothing common.  I know: I've looked for a solvent-weld chemical to fix polyethylene/polypropylene stuff (high or low density) and nothing fazes it.

Except heat, of course.    Then it flows like the wax it so closely resembles (chemically).



Which brings me to another question:  what lined the chemical cars prior to the widespread use of polyethylene/polypropylene?  Wax...?

[Swatopluk]

I essence, yes. Paraffine would be the term used. Maybe combined with some stabilizer.

Btw, some mad pranksters haunt(ed) the Berlin subway system with HF pens. In the past windows were scratched with diamond pens, these guys use fountain pens (or something like that) with HF. That is 'easier' and leaves a surface that is harmful to touch for quite some time. Apart from being toxic, fluoride inhibits healing.

---

Cyanides are used for galvanic baths because they yield the smoothest deposition of coatings. They are also used in goldmining for the purpose of separation of the gold from other components (I leave it to you, whether that is an improvement over mercury).

[Bob in a quantum-state-of-faith]

... Btw, some mad pranksters haunt(ed) the Berlin subway system with HF pens. ...

A while back, those were "all the rage" as an anti-theft item for cars.  The idea, was to inscribe your vehicle's VIN into all it's glass, as there were any number of auto theft and dismantling rings about-- fully 1/3 of the value of a stolen car (parts-wise) was it's glass.  If it was marked with a VIN, it was useless (or so the strategy went).

So, jumping into that particular bandwagon, some companies began marketing HF pens to do just that:  mark the 'un-markable'.   The pens did exactly what they were sold to do, but they also did much, much more, little of it positive.

Soon enough, the practice was quietly discouraged:  it wasn't effective anyhow.   The thieves would simply discard the marked glass-- after all, they had "invested" nothing in acquiring the auto in the first place...

[Swatopluk]

In one South American country (forgotten which) it was once* mandatory to have the licence number engraved in the windshield for that purpose.

*definitely before 1970