Sparex No 2 101

Jewelry Discussion
61 
If you are going to use PH down (sodium bisulfate), for your
pickle, keep in mind that this is a swimming pool chemical. It
regulates the PH in the water for pools and spas. So... the bottom
line is you need to dilute it, not neutralize it; no other
chemicals needed except more H2O.

begging to differ there Beth, Sdium bisulphate is a chemical the
exact same as sparex. if you would neutralize sparex ( and you
should for the environment) you should also neutralize pHdown. It is
simply a far cheaper way to buy sparex #2…none of the other H20
theorem matters or has a thing to do with the bottom line which is a
chemical is a chemical is a chemical…and pickle needs neutralizing
in the jewelry studio unless using it for plating.

RER

62 
take that pseudo-medical half-truth with a large grain of kosher
salt-

This thread’s pretty incredible, I think. Ya take your Sparex or
similar, Ya take your water, Ya mix em together… Nice thing
is, ever since the days of Rutherford and Lavoisier, we can have
science, or chemistry fact:

If there’s any such thing as pulmonary arrest as a reaction to
sulfuric acid, it’s news to me - a link to that would be
helpful Now drowning to death and gasping due to pulmonary
edema, which is certainly an effect that is known, that’s different.

Dilute sulfuric acid does not dissolve copper, period. Hot
concentrated acid does, but that’s another story. If it did, you
would shortly not have a vessel, now would you?

Since the designed purpose of a jeweler’s pickle solution is to
remove boron glass from soldering, and sodium bisulfate is 100%
effective at that,we can say that it is, indeed, 100% efffective. I
also have used sulfuric acid pickle, and it is quicker and more
efficient, it’s true, but the danger of mixing and storing acid is
far outweighed by that, which is why the industry lives on Sparex.

Sulfuric acid does not form sulfides, and never will without a chem
lab. Sulfuric acid (H2SO4) forms sulfates, sulfuous acid (H2SO3)
forms sulfites, and sulfur or it’s compounds, such as hydrogen
sulfide forms sulfides.

Will all this in mind, if you have sulfuric acid in a copper vessel
and it dissolved the vessel, you will shortly have a solution of
copper sulphate, and it will be brilliant ultramarine blue, quite
poisonous, by the way, and completely useless as the acid will be
depleted.

It could quite well be that there is some bi-metallic action
happening with pickle in a copper pot, but since pickle in a glass
pot is 100% effective at it’s designed job, I’m not sure that it
matters unless there’s some certain circumstance where it applies.

I am sorry if this is blunt, but please check facts before posting.
Misabout chemistry is dangerous and quite easily
researched before hand. There is much chemical lore in our trade,
but it’s quite simple to check the facts, if one is inclined to.

63

G’day;

Speaking of neutralizing Sodium bisulphate, are there any toxic
gases produced when neutralizing Sodium bisulphate with baking
soda in the kitchen sink or should I be doing this outside?

The gas produced in neutralising sodium bisulphate is carbon
dioxide; the same gas that gives Cola, lemonade, beer, etc the ‘fizz’
Not toxic or poisonous in normal concentrations. Don’t worry about
it. There’s plenty in the atmosphere anyway; all plants use it as a
food!–

Cheers for now,
JohnB of NZ

64

G’day;

Doing it in copper vessel, acid is used up reacting with copper and
the result is copper sulphide and water*

The reaction between hot strong sulphuric acid and copper produces
sulphur dioxide, which is a nasty choking gas, and not copper
sulphide but copper sulphate. There is little point in using a
copper vessel. A glass Pyrex or Chance beaker or flask is excellent.
There is little point in boiling the acid as warm sulphuric acid or
’pH down’ works well at about 40C to remove sulphide stains from
silver or low carat gold. (copper sulphide stain in this case)
Silver, gold, platinum or other of the ‘noble’ or precious metals
will not react with sulphuric acid or the sulphate ion.–

Cheers for now,
JohnB of NZ

65 
The gas produced in neutralising sodium bisulphate is carbon
dioxide; the same gas that gives Cola, lemonade, beer, etc their
'fizz'

Hi, John, good to know you’re still listening in! I hope you and
Jean are both well and will have a great new year,

Noel

66 
If there's any such thing as pulmonary arrest as a reaction to
sulfuric acid, it's news to me.

If your comment means that breathing in acid vapors do not have
consequences, than you should take your own advice and check the
facts. Also consider that having any chemical liquid open will result
in evaporation and vapors will carry minute particles of the liquid (
acid in our case ) with them, so if you are in the room with the open
container containing the hot liquid, you are breathing it in.

The hotter the liquid, the more pronounced the effect. Pulmonary
arrest implies immediate reaction to a contact. That is not what I
wrote.

Prolonged contact with acid leads to neurological damage which can
lead to severe damage to lungs and pulmonary arrest as a consequence.
Beside if smoking is dangerous, what do you think pickle vapors doing
to your lungs?

Dilute sulfuric acid does not dissolve copper, period. Hot
concentrated acid does, but that’s another story. If it did, you
would shortly not have a vessel, now would you?

What needs to be understood here is the action of boiling a
jewellery in a copper vessel containing dilute sulphuric acid is not
the same as conducting reaction between copper and dilute sulphuric
acid.

I will help you to understand this process.

First what must be realized is that text book reactions assume pure
components which do not exist in real world. Second is the
concentration of the solution is changes as boiling progresses.

With this in mind let’s examine what happens in the pot. The purpose
of pickling is not only to remove melted flux but also to remove
oxides. Working with gold alloys creates copper oxide since most of
practical gold alloys contain copper. Copper oxide react with dilute
sulphuric acid readily.

Cu2O + H2SO4 = Cu + CuSO4 + H2O

In words the result is copper, copper sulphate, and water. So the
process like this. We put jewellery in a copper pot, add dilute acid
and boil it under the hood. Flux is dissolved together with copper
oxides, pure copper is deposited on the bottom of the pot and copper
sulphate stays in solution.

Remaining acid stays a pot since since, like you stated, it does not
reacts with copper, but I would add to this practically, since there
is no such things as total inertness.

Immediately after boiling the concentration of the acid increases
due to water evaporation and some consumption of deposited copper
takes place, but since sulphuric acid is hydroscopic, the
concentration will fall in time. Eventually solution turns blue and
needs to be replaced.

but the danger of mixing and storing acid is far outweighed by that,
which is why the industry lives on Sparex.

Here is the link to sodium bisulfite MSDS

http://physchem.ox.ac.uk/MSDS/SO/sodium_bisulfite.html

Anybody who thinks that it is safer than sulphuric acid should read
it. Pickle based on sulphuric acid you keep cold and bring it to boil
only when needed, Sparex must be kept hot in a busy shop. It works
cold but takes too long. So even if we assume it is 100% effective,
which is not, the exposure to hot vapors throughout the day is far
more dangerous than having cold container of dilute sulphuric acid.
As
far as handling the acid, it is not that complicated.

I am sorry if this is blunt, but please check facts before
posting. Misabout chemistry is dangerous and quite
easily researched before hand. There is much chemical lore in our
trade, but it's quite simple to check the facts, if one is inclined
to.

I like blunt. I am not much into mincing the words myself, so it is
always good to remember that what appears as miscould be
our haste in judging the and failure to understand the
process for what it is.

Frankly, when I started in this business, one could not even find a
bench without a small copper pot hanging on the side of it, used for
pickling. Everybody used his own. My first exercise in working with
metal was making a scoop for filing and the second was making a
pickle
pot out of copper. So I am really surprised that you are not aware of
this procedure.

Leonid Surpin.

67 
There is little point in boiling the acid as warm sulphuric acid
or 'pH down' works well at about 40C to remove sulphide stains

In my shop, parts are made, polished and assembled. Working with
polished components requires that only minimum amount of solder is
used. Cleanup is not always possible, and frankly what is the point
or polishing if excess of solder needs to be filed afterwards. But if
one uses only minimum amount of solder, the solder does not bridges
the gap if temperature of the sides of the joint is unequal. Solder
only flows on the hotter side. It happens from time to time.

This effect is not apparent in normal practice because in majority
of situation more solder is used than necessary. There are other
reasons why joint may appear to soldered, but in reality it is not.
It is soldered with glass which formed when flux melted and there may
be partial metallic bondage here and there, but such a joint cannot
carry any structural load. If this is the case, boiling it in acid
would reveal the flaw. It works because when jewellery is boiled,
due to thermal expansion the joint becomes larger and acid can attack
the flux filling the joint. Warm pickle will not do the trick, at
least not in the reasonable amount of time.

Otherwise, I have seen when setting would survive 3 rounds of
polishing with steamer and ultrasonic treatment, but once the ring is
sold, it invariably fails on the clients finger. Boiling jewellery in
pickle and examining under magnification afterwards would prevent it
from happening.

Leonid Surpin.

68 
Boiling process also drives small particle of the acid in the air
and that gets in the lungs. Doing it in copper vessel, acid is used
up reacting with copper and the result is copper sulphide and
water.

Hmmm, interesting. I happen to have a pure copper lid on my pickle
crock, because it was lidless and I had an old copper bowl I had
made that fit it. This copper lid gets a beautiful rich green patina
inside it, which I occasionally scrub off. Perhaps the copper is
helping the air quality in my studio, by catching the particles and
forming the sulphide? Leonid? Helen?

M’lou Brubaker
Minnesota, USA
http://www.craftswomen.com/M’louBrubaker

69

As John pointed out yesterday, I can’t see why copper sulphide would
be produced at all! Sulphuric acid in solution produces H+ (acidic)
ions and SO4- (sulphate) ions. The copper in the vessel will react
with the sulphate ions to give the blue solution of copper sulphate.
It may well be that a high concentration of copper sulphate crystals
on your lid take on a greeny turquoise colour.

Copper sulphide is grey-blue to black but I can’t see where you’d
get sulphide from. You WILL get copper sulphate which is the
beautiful turquoisey blue colour.

Helen

70

At a risk of been repetitive, I would have to point out again that
reaction is not between the copper and the acid. But to make a larger
observation.

One philosopher, his name escapes me now, once said. Paraphrasing -
There are two kind of people. One kind observing a relative crossing
the road, which has been buried last week would say to himself and
the others.

“Look at this guy. He should be dead, but here he is walking among
us”. The other kind would promptly schedule an appointment with a
psychiatrist. The moral of this tale is, it is always advisable to
search for a reason for not understanding something within oneself
before assuming that “a dead relative came back to life”.

Leonid Surpin.

71

good method for saving electricity…a few microwave minutes a week
vs. leaving it plugged i and on auto always as some do…makes sense
for very small scale production and small work areas…one hint- try
and find a container with a non-metallic lid for storage though…the
iron oxide can contaminate the pickle after a fairly brief while as
it develops around the rim of the jar readily in humid areas…

rer

72

Hi James, my understanding is that the only thing coming out of a pickle pot or I guess a jar in the microwave is steam - pure water vapor. Just like heating mineralized water to produce pure, distilled water. I thought that the only time it was hazardous was dropping a hot piece in vaporizes the acid along with the water. Am I totally uninformed?

73

I use my pickle cold most of the time now because I find there is considerable corrosion of my tools when I use hot pickle. Could be all in my mind, but there it tis.
Aurora

Hi James, my understanding is that the only thing coming out of a
pickle pot or I guess a jar in the microwave is steam - pure water
vapor. Just like heating mineralized water to produce pure,
distilled water. I thought that the only time it was hazardous was
dropping a hot piece in vaporizes the acid along with the water.
Am I totally uninformed?