From: REMOVE_THISdwilkins@means.net (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Re: Hydrochloric and Muriatic Acid
Date: Tue, 02 Nov 1999 17:55:59 GMT

On Mon, 1 Nov 1999 22:54:09 -0600, "Bob Hanson"
<rhanson@computron.net> wrote:

>You can still get "Muriatic Acid" in just about any hardware store.  I keep
>some in the garage to use around the house.  It is just dilute (about 15%)
>Hydrochloric acid.  The "killed acid" is a process that used to be used but
>I doubt that it is still used to produce the flux.  Bob Hanson


I used to think (long ago) that it was "just dilute hydrochloric
acid".  I am a chemist (retired) and use it to clean lots of stuff.
The most recent bottle I picked up at the local hardware store turned
out to be 20 degree Baume which if I remember correctly is about
31.5%. Now the concentrated hydrochloric acid that we had in the lab
was about 36% HCl so this stuff is far from being dilute HCl.

I knew as soon as I opened the cap that it was pretty strong because
the fumes were obvious. 15% acid won't fume like that.

My suggestion is to read the label before doing dilutions because all
muriatic acids are not created equal.

AFAIK zinc chloride is still produced by dissolving either zinc oxide
or zinc metal in hydrochloric acid. A 10% solution of zinc chloride
(in water) will be slightly acid. I wouldn't be surprised if the flux
is still prepared this way.

<stuff snipped>

From: REMOVE_THISdwilkins@means.net (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Re: Phosphoric acid questions
Date: Wed, 14 Jun 2000 13:42:18 GMT

On Tue, 13 Jun 2000 21:46:23 -0700, Eastburn <oldtree@pacbell.net>
wrote:

>,;Right!
>,;
>,;HCL is the lab grade stuff.
>,;Muratic Acid is the pool grade / utility acid.
>,;Muratic Acid is low grade HCL.  Not poor - just might have some
>,;extra mineral in it less refinement.

Muriatic acid is not necessarily a low grade HCl. Years ago it usually
was off color (yellow) due to some iron contamination sometimes green
also due to iron contamination. Currently the stuff I get at the
hardware store is water white which suggests that it has been
distilled. It usually runs 20-30% HCl. Lab grade concentrated HCL runs
36-37 % HCl.

>,;It is dangerous stuff - HCL loves to eat flesh, clothes,
>,;and is dangerous around Al.  It can almost explode with the
>,;gas liberation with AL.

I don't consider it dangerous.

HCl does not eat flesh. It is one of the strong concentrated acids in
the lab which does not cause us to run for the sink if we get it on
our hands. It does sting if it gets in to cuts or scratches but if you
get it on the skin you can walk casually to the water source and
rinse. After rinsing you will have no skin damage unless you were a
damned fool and left it on the skin for hours. You would need to be a
glutton for punishment to do that as it does itch enough to let you
know it is there.

HCl does not eat clothes. Yes it can damage some fabrics but in most
cases a water rinse will eliminate any problem. One notable exception
was nylon stockings. A young female technician dropped a 2.5 liter
bottle of concentrated nitric acid and it splashed up at least to her
knees. She panicked and started screaming and jumping up and down. I
grabbed her and dumped her in the sink and drenched her with water.
The nylons disintegrated and it looked like skin coming off. She came
out of it looking like a drowned rat without stockings up as far as I
could see but with no acid burns.

HCl would also have removed the nylons but I would have been more
casual about the rinse and more careful about where I used my hands to
wash the acid off.

HCl is not dangerous around aluminum. In fact it is difficult to get
the reaction going because of the adherent oxide layer on aluminum. It
does not explode. Once the reaction gets going it can get vigorous
enough to bubble up out of the container but it isn't going to explode
spontaneously.

>,;Remember - Chlorine gas is liberated from either.  Also Hydrogen.

Chlorine gas is not liberated from HCl unless you have a rather strong
oxidizing agent present. Hydrogen gas is not released unless you have
a reducing agent.

Other than those minor changes you got it pretty much correct.

Newsgroups: rec.crafts.metalworking
Subject: Re: Phosphoric acid questions
From: Ole-Hjalmar Kristensen <ohk@clustra.com>
Date: Thu, 15 Jun 2000 08:41:24 GMT

REMOVE_THISdwilkins@means.net (Don Wilkins) writes:

<stuff deleted>


> Chlorine gas is not liberated from HCl unless you have a rather strong
> oxidizing agent present. Hydrogen gas is not released unless you have
> a reducing agent.
>
> Other than those minor changes you got it pretty much correct.
>

Which reminds me of the interesting mix of hydrochloric acid, hydrogen
peroxide, and water we used to etch prited circuit boards. It would do
the job in less than a minute. Scary stuff.

--
"Plus I remember being impressed with Ada because you could write an
 infinite loop without a faked up condition.  The idea being that in Ada
 the typical infinite loop would normally be terminated by detonation."
                                             -Larry Wall

Ole-Hj. Kristensen

From: REMOVE_THISdwilkins@means.net (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Re: Cleaning copper
Date: Wed, 30 Aug 2000 08:31:23 -0500

On 29 Aug 2000 10:41:52 GMT, cheisolly@aol.comspamnix (Che is Olly)
wrote:

>,;You could dip it in Muriatic acid then rinse with cold water. Acid cut with
>,;water by 50% should clean that.
>,;The cable end could be held in the acid water solution
>,;for a few minutes then rinsed. Repeating as necessary.
>,;Of course gloves and goggles are recomended.
>,;The acid should be poured into the water instead of vice versa. Good Luck
>,;remove "spamnix" for correct address

Probably good advice because of the problem with concentrated sulfuric
acid and water but for the record. You can pour either way with
hydrochloric acid. The heat of solution is not enough to cause
boiling.

Regarding the use of hydrochloric acid for cleaning copper.

The oxides of copper are quite soluble in hydrochloric acid. You end
up with a what we called a "salmon" color. Copper metal will not
dissolve in HCl so it is a safe way to clean with a solution which is
easy to rinse.

There is a hook (as usual) IF there is dissolved oxygen in the acid
then copper metal will go into solution. This not a problem for a
quick clean but if you leave the copper in the acid for a long period
of time you will dissolve copper and it will be particularly
noticeable at the acid air interface where the oxygen concentration is
highest.