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Chemicals!


#1

As a beginner, I am intrigued by all the wonderful surface treatments
I am seeing on silver. I want to experiment with reticulation and
photo etching. While roaming the internet to get an idea of what these
projects are going to cost me, I became bewildered by the variety of
acids out there. Every chemical/lab supply house has several
different strengths of most acids, ranging from what appears to be
pure acid down to 10% solutions and everything in between. I have
three texts that include these techniques. They all say to mix X-parts
of acid with X-parts of water. But, none of them deal with the
strength of the acid starting out. You could get a wide range of
results!!!

So…what strengths/types of sulfuric and nitric acids do you use in
these processes?

Storage and safety tips would also be appreciated.

One last question…do you have recommendations for a good source?
I’m on the East coast - D.C. area. I haven’t hit the bricks looking
for a local chemical supply yet. The last time I did that - looking
for large quantities of lye for a home soap-making business - I was
treated like the Village Idiot. Or Master Criminal, depending on the
supplier. You’d have thought I was asking for a kilo of cocaine.

Thanks for sharing!

Suzette Crim


#2

Suzette, regarding your questions on how to obtain the chemicals to
use in your jewelry processes, there are some safety concerns for your
own personal health. Some chemicals are inappropriate in a home
studio, or at the very least, should only be used with a good deal of
caution. Whenever possible, use the safest alternative possible. The
reason chemical supply companies are wary of selling chemicals to the
general public is because so many people use them to make bombs and
other incendiary type of devices, and ultimitately, they can get into
big trouble for having sold the chemicals. Here’s some tips:

Contact a chemical company that is familiar with supplying jewelers,
such as Bryant Labs. You might ask other jewelers in your area where
they get their supplies for the particular processes you’re interested
in doing, so that you have a local source and avoid the exorbitant
shipping fees. Next, send an introductory letter to the supplier,
stating what business you’re in, what chemicals you’re interested in,
about how much you intend to use, how it will be used specifically,
how it will be stored and disposed. Provide supporting documentation
of your business, such as tax number, licenses, yellow page ads, etc.,
so they know you’re not just some quack off the streets.

Before deciding you really need any chemical, do your research. Look
up the MSDS (Material Data Safety Sheets) online and decide if you
really want to accept the risks, and if there are any involved
disposal methods. Some chemicals cost more to dispose of than the cost
of the initial purchase. Next find someone who is familiar with using
the chemicals you want to use on a routine basis, and really pump them
for on handling, storage and disposal. Will it react with
other things? Can you store it with other chemicals safely? How do you
neutralize it in case there’s an accident? How will it react with the
processes you’re using it for? Will there be special handling
equipment, such as positive ventilation, positive oxygen flow, special
clothing?

You mentioned wanting to etch silver. Ferric nitrate is slower, but a
lot less hazardous than nitric acid by itself. Or etch onto brass with
ferric chloride, and cast or rollerprint from that.

You’re asking for a lot of broad ranging We can help you
better if you ask one specific question at a time as you have a need for it.


#3
     Every chemical/lab supply house has several (acids) But, none
of them deal with the strength of the acid starting out. You could
get a wide range of results!!! So...what strengths/types of sulfuric
and nitric acids do you use in these processes? 

G’day Suzette; The strong acids such as sulphuric, nitric, and
hydrochloric are actually saturated solutions of gases in water.
Sulphuric acid is made by dissolving sulphur trioxide gas in water
until it won’t dissolve any more. It is then called concentrated
acid, and is sold as a standard strength. The same goes for
hydrochloric acid; this is a solution of hydrogen chloride gas (made
by boiling conc., sulphuric acid with sodium chloride) in water until
saturated and is 35.5%. Nitric acid is made by boiling a nitrate
(sodium or potassium which are mined in hot dry countries) with
concentrated sulphuric acid and distilling off the concentrated nitric
acid. Thus, these three acids are all of standard strength and
composition. So ten percent sulphuric acid is made by pouring say,
100 mls of concentrated acid into about 700 mls of water with constant
stirring, then, when it has cooled, adding more water until you have
1000 mls of 10% acid. Admittedly if you do the same to make up
hydrochloric acid, it won’t be 10% as the conc. acid is only 35.5% So
you’d have to do a simple calculation to come up with the right
amount. However, for most practical purposes, precise strengths of
diluted acids are not important. I can only hope this has not added to
further confusion!

    Storage and safety tips would also be appreciated. 

All the three acids above (often called ‘the mineral acids’ are best
stored in glass bottles, although some are sold in plastic bottles
these days. Do not use common corks as stoppers; they won’t last
long. Even rubber stoppers soon deteriorate with nitric acid. They
all used to be sold and used from glass stoppered bottles, especially
in labs (one of my first jobs at 14 was to fill all the bottles in a
teaching lab) But these days many different kinds of plastic are
used. Store them in a cool place out of direct sunlight.

     I haven't hit the bricks looking for a local chemical supply
yet.  The last time I did that - looking for large quantities of lye
for a home soap-making business - I was treated like the Village
Idiot.  

Many supermarkets sell ‘lye’ either as it’s usual name of caustic
soda, or (in America) as Drano. Our larger hardware stores sell
hydrochloric acid, (used in soldering galvanized iron) and caustic
soda (used for cleaning drains, soap making, etc). Garages sell
battery acid, which is sulphuric acid around the 10 - 12% strength
area. Cheers, –

John Burgess; @John_Burgess2 of Mapua Nelson NZ


#4

Suzette, maybe your questions have already been answered adequately,
but here’re my opinions. I share your frustration regarding chemical
mixing directions which do not specify the strengths of the products
to be mixed. In the case of nitric acid (of which I am very fond), I
use the industrial grade, which is cheaper than the purer reagent
grade. I pay about $5 for a half-gallon of the stuff, which lasts me
a very long time (because I’m only a part-timer at jewelry-making). I
dilute that nitric acid 50:50 with water (“acid into water”) and use
it for bright-dipping (removing the red copper oxide left over from
soldering or annealing). When it’s fresh, it works VERY fast [stand
back when using it the first few times–it may give off a little brown
nitrous oxide, which is nasty], and over time it just gets slower and
slower and darker and darker (blue). But always stay there and watch
the action of the acid (it varies with temperature). I once stepped
away to do something else, forgot my piece temporarily, and when I
remembered, it had etched all the way through in places! (Of course,
being too cheap to throw anything away, I thought it looked kind of
cool that way and soldered the remnants to a backing plate–it looked
much better than my original idea. My best designs have come from
various mistakes I’ve made…). I finally purchased a little
kitchen timer to set for a minute or two, if I just can’t spend the
time watching my piece being bright-dipped for a few minutes when the
acid is weaker. When the acid gets too weak for bright-dipping, I
sometimes use it for etching. For disposing of really tired nitric
acid, check some jewelry books. Do not just pour it down the drain! I
bright-dip in a Pyrex pie plate which I keep covered with a glass
cover. I NEVER allow unaccompanied children (or, for that matter,
adults!) in that area of the basement where I work. The glass bottle
of nitric acid I keep on the floor [not on a shelf], under a table
where there’s no traffic, inside a bigger plastic container, inside a
cardboard box. It’s important when working with any acid to not be in
a hurry. In 20 years, I have never had any problems with nitric acid.
I like the option of the hydrogen peroxide-Sparex mixture, and I
recommend it to my students. But its disadvantage is that the
hydrogen peroxide decomposes in a few hours. Nitric acid is stable
for years. Since you live near D.C., look in the Yellow Pages for
chemical supply houses. Take your business card with you, so that
it’s clear that you need acid for business purposes (not malevolence).
HTH!

Judy Bjorkman
@JLBjorkman