Homebrew PCBs

At 9:59 am ((PST)) Sat Jan 27, 2007, Randy Ledyard wrote:
> > [mailto:Homebrew_PCBs@yahoogroups.com]On Behalf Of Lez
> > I have used their driveway cleaner before, my neighbor came out
> > complaining about the smell, I was stood in the middle of a 10ft
> > diameter well wet area and could not smell a thing, I thought he was
> > 'in need of medication' till the wife came out and complained too, I
> > guess I just could not smell the stuff, rotten eggs I think he said,
> > does that sound familiar?

Rotten eggs = hydrogen sulphide, common as a laboratory reagent
and dangerous because it's toxic and it anaesthetizes the sense of
smell - so those most at risk don't realize they are being poisoned.

>That sounds like it must have been Sulfuric Acid-based (H2SO4), and you
>somehow generated Hydrogen Sulfide (H2S) - which gives off the "rotten-egg"
>smell

H2S was probably liberated by the acid from some rotted organic
residues , possibly in a drain - it doesn't prove what the acid was.
(BTW, not hazardous unless you stick your head down the drain.)

>And that is _NOT_ the acid you want....

Not what Lez was asking for, but it would do the job, as would
battery top-up acid if it were cheaply available.

Also sulphamic acid - a beige crystalline powder like light brown
sugar, often sold for kettle descaling, with an activity similar to
sulphuric acid and the convenience of a non-hygroscopic powder.
However, branded retail packaging makes that uneconomic.


Regards, LenW