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Etching on silver 101


#1

Hi,

My name is manuel and I am about to start doing etching on silver.
Can someone tell me if ferric nitrate gives better results than
nitric acid?? and do either or both should be diluted with water or
not?? Is bakind sodarecomended for both as a neutralizer?

I will appreciate the advice and recomendation?

Thanks
Manuel


#2

Hi,

I don’t think ferric nitrate works, coz silver is more stable then
iron. Nitric acid will do the work, but you need to be careful when
dealing with nitric acid, it is quite corrosive. Baking soda could
neutralise the overdose acid, but it would cause some decipitation
of silver carbonate. It is better to just collect the solution after
the etching and then add some iron, you can recuperate the silver
etched.


#3

While ferric Nitrate works more slowly, Nitric is the ideal acid for
etching silver and other metals. Check each bath with the test
wherein the sample metal testing will show rising bubbles from the
floor of the bath. This action determines the proper mix. The 2/3
water and 1/3 acid is the proper mix for best results. Baking soda
will neutralize the used acid mordant


#4
Can someone tell me if ferric nitrate gives better results than
nitric acid?? 

You get less undercutting with ferric nitrate, so a smoother, though
somewhat slower, etch.

and do either or both should be diluted with water or not?? 

Well, certainly your nitric acid needs to be diluted. I like about
10 to 15 percent concentration. Pure/concentrated nitric acid is not
only much more dangerous to work with, but actually doesn’t etch as
well.

Ferric Nitrate, pure, is a solid crystalline salt. So wondering
whether to dilute it is the wrong question. Instead, ask what
concentration solution, how much chemical to how much water, you
should use. And for that, I don’t actually have an answer. But
someone will…

Is bakind sodarecomended for both as a neutralizer? 

Yes, if you need a neutralizer. After etching, a simple thorough
water rinse removes the etching acid. You may not need a neutralizer
at all if you don’t want. But it’s never a bad idea to have some
around for spills. Any other alkaline material (like soap, detergent,
your ultrasonic cleaning solution, etc, for example) will also
neutralize traces of acid.


#5

Hello Manuel,

This is something Ive been meaning to experiment with myself… Ive
opted for Ferric Nitrate but havent yet tried it out, I believe it
to be a much slower process but gives far more accurate results. Ive
used Nitric Acid in the past for which gives a faster etch but does
tend to undercut. Anyway, the formulas for both are below.

1 part nitric acid to 3 parts water.

1 part ferric nitrate to 4 parts water.

Both can be neutralized with Bicarbonate of Soda.

Let us know how you get on.
Regards
Emma


#6

Hi Manuel,

If you search the Orchid Archives, something I urge everyone to do
for tips, cause its pretty durn amazing, and there are quite a few
posts on etching silver.

A mordant (acid) is a mordant; nitric acid is a quick etch requiring
a good exhaust system, eye and body protection. It works very well,
but one must weigh the consequences of storage, usage, safety and
disposal. It is for these reasons that I use ferric nitrate.

Ferric nitrate is a slower etch. The same safety precautions should
be noted, but if ferric nitrate spills on your body or your
surroundings, it is much safer to deal with spills.

In both cases, which ever one you choose, always add acid to water.

Nitric acid comes in a liquid form. I have not used it, so it might
be through your Orchid archives search, you might use it full
strength. I think I did in college but we had a weak solution that
didnt seem to work well.

Ferric nitrate comes in crystal form. I suggest purchasing yours
from Artchemicals.com and is a very good company whose mission is to
serve artists.

For ferric nitrate I use 1 cup of ferric nitrate crystals to 3 cups
of water. You want the solution to look like strong tea. After using,
decant the spent solution into a plastic bottle with a screw top.
This can be any juice bottle or water bottle, it doesnt matter.
Disposal should be through your towns hazardous waste and the bottle
marked with a date.

For setup, there are some good tips in the archives. I would give
them to you here, but then you wouldnt use the archive database that
Hanuman has set up for us which makes Orchid unique. If you still are
having problems, finding them, then email me offline and I will point
you in the right direction. Ive written extensively on etching, so
start with my name and use ferric nitrate in the search. Noel
Yovovitch is another person who has etched metal and has a lot of
good info for you.

With kind regards,

Karen Christians
Cleverwerx


#7
Well, certainly your nitric acid needs to be diluted. I like about
10 to 15 percent concentration. Instead, ask what concentration
solution, how much chemical to how much water, you should use. And
for that, I don't actually have an answer. But someone will... 

I’ll say it again. There is a very simple formula for arriving at a
desired concentration of any solution and I’ve posted it a few
times. PLEASE don’t be put off by the length of this post. It’s
simple mathematics which is very easy to understand and once it’s
understood that you can use it for any solution you need, you’ll want
to note it down somewhere - preferably in your workshop where it’s
easily accessible - laminated on the wall perhaps.

Final concentration X final volume = original concentration X
original volume (I may have quoted it the other way round before now,
but it doesn’t matter, one side of the equation equals the other so
it works both ways).

From what I can gather, individuals can purchase nitric acid up to a
concentration of 38%. Peter says that he likes 10-15%. So we can very
simply calculate how much water our nitric acid (38%) should be added
to.

We know our original concentration is 38% (in our example -
substitute whatever concentration you have purchased), and we know we
want to achieve a final concentration of 10%, so that’s not a
problem. However, with the volumes in our equation, we need to decide
one of the volumes so that we only have one unknown. It doesn’t
matter which one - it works for both. If we decide that we want to
add 20ml (0.2 litres) of 38% nitric acid, then we know the original
volume and it will be our FINAL volume which will become our unknown
(the answer to the equation).

I’ll abbreviate so it doesn’t go too far across the page. Final
concentration will be fin conc., final volume will be fin vol.,
original concentration will be orig conc., and original volume will
be orig vol. I’ll use the letter “Y” as our unknown (in this case to
represent the final volume). Our desired 10% solution will be
presented as 0.10 (ie 10 hundredths), our 38% as 0.38. It is simpler
to represent percentages thus, rather than having fractions such as
38/100 in our equation - obviously that works just the same but it
can get confusing. 20 ml will be presented as 0.20 (ie 0.20 litres)
and so on. Always be consistent with units, ie don’t mix ml with
litres within an equation.

fin conc. x fin vol. = orig conc. x orig. vol

0.10 x Y = 0.38 x 0.20

so, rearranging:

Y = (0.38 x 0.20) / 0.10

Y = 0.076 / 0.10

Y = 0.76 litres (76 ml)

IMPORTANT NOTE: 76 ml is the total final volume. This INCLUDES the
20 ml added acid, so you need to subtract that from 76 to find out
how much water is needed. 76 ml - 20 ml = 56 ml. Therefore, you would
need to add your 20 ml of 38% nitric acid to 56 ml water to achieve
your 10% solution.

If you want to use the equation the other way around and arrive at
say a final volume of 500 ml (0.5 litres), then Y (our unknown) will
now become our original volume (ie how much 38% nitric acid to add to
water).

fin conc. x fin vol. = orig conc. x orig. vol

0.10 x 0.50 = 0.38 x Y

so, rearranging:

Y = (0.10 x 0.5) / 0.38

Y = 0.05 / 0.38

Y = 0.13 litres (13 ml)

Again, IMPORTANT NOTE: Your 500 ml final volume is the total volume,
therefore you need to subtract 13 ml from 500 ml to determine how
much water you need to add the 13 ml of acid to. 500 ml - 13 ml = 487
ml water.

I hope this helps. It really is simple once you get your head around
what figures to substitute into the equation. Hubby says I should
post a blog about it rather than keep posting emails every time
someone asks the question. I may just do that. Then when the question
comes up again, I can post a link to my blog. But in the meantime,
this will do the job.

Any questions, drop me an email.

Helen
UK
http://www.hillsgems.co.uk
http://helensgems.ganoksin.com/blogs/


#8

Anyway, the formulas for both are below.
1 part nitric acid to 3 parts water.
1 part ferric nitrate to 4 parts water.

I’ll repeat another point I’ve made before, even though I got some
flack for being so pedantic. It depends what concentration you are
using as to what ratio to use. You can’t simply state use 1 part
this to 3 parts that, without giving a concentration for the acid (or
whatever your solute is). See my other post of today for a more in-
depth way of calculating how to mix nitric acid (and other
solutions).

I am NOT being critical of the poster quoted above, just stating
that it’s more complex than suggested.

Helen
UK
http://www.hillsgems.co.uk
http://helensgems.ganoksin.com/blogs/


#9

SORRY! I’ve just realised that I made a glaring mistake in my
lengthy post with regard to how to calculate the amount of water
needed to dilute nitric acid!!!

In my first calculation, I said that 20 ml was 0.2 litres! Of course
it isn’t. It’s 0.02 litres. It does, however, still work out
correctly when I’ve interpreted the answer afterwards, ie 76 ml
total volume - 20 ml acid = 56 ml water (a rather small amount to
work with so it could do with scaling up, substituting a different
starting figure into the equation to find the amount of water
needed). I’ve then made a similar mistake in the second calculation,
saying that 0.13 litres is 13 ml - which is clearly wrong. It is 130
ml. If you don’t make the same daft mistake I did, then you’ll get it
right every time.

So, I’ll post it again, but corrected as follows:

Final concentration X final volume = original concentration X
original volume (I may have quoted it the other way round before
now, but it doesn't matter, one side of the equation equals the
other so it works both ways). 

From what I can gather, individuals can purchase nitric acid up
to a concentration of 38%. Peter says that he likes 10-15%. So we
can very simply calculate how much water our nitric acid (38%)
should be added to. 

We know our original concentration is 38% (in our example -
substitute whatever concentration you have purchased), and we
know we want to achieve a final concentration of 10%, so that's
not a problem. However, with the volumes in our equation, we need
to decide one of the volumes so that we only have one unknown. It
doesn't matter which one - it works for both. If we decide that
we want to add 20ml (0.02 litres) of 38% nitric acid, then we
know the original volume and it will be our FINAL volume which
will become our unknown (the answer to the equation). 

I'll abbreviate so it doesn't go too far across the page. Final
concentration will be fin conc., final volume will be fin vol.,
original concentration will be orig conc., and original volume
will be orig vol. I'll use the letter "Y" as our unknown (in this
case to represent the final volume). Our desired 10% solution
will be presented as 0.10 (ie 10 hundredths), our 38% as 0.38. It
is simpler to represent percentages thus, rather than having
fractions such as 38/100 in our equation - obviously that works
just the same but it can get confusing. 20 ml will be presented
as 0.02 (ie 0.02 litres) and so on. Always be consistent with
units, ie don't mix ml with litres within an equation. 

fin conc. x fin vol. = orig conc. x orig. vol 

0.10 x Y = 0.38 x 0.02 

so, rearranging: 

Y = (0.38 x 0.02) / 0.10 

Y = 0.0076 / 0.10 

Y = 0.076 litres (76 ml) 

IMPORTANT NOTE: 76 ml is the total final volume. This INCLUDES
the 20 ml added acid, so you need to subtract that from 76 to
find out how much water is needed. 76 ml - 20 ml = 56 ml.
Therefore, you would need to add your 20 ml of 38% nitric acid to
56 ml water to achieve your 10% solution. This is only a small
amount so you may want to scale it up somewhat. 



If you want to use the equation the other way around and arrive
at say a final volume of 500 ml (0.5 litres), then Y (our
unknown) will now become our original volume (ie how much 38%
nitric acid to add to water). 

fin conc. x fin vol. = orig conc. x orig. vol 

0.10 x 0.50 = 0.38 x Y 

so, rearranging: 

Y = (0.10 x 0.5) / 0.38 

Y = 0.05 / 0.38 

Y = 0.13 litres (130 ml) 

Again, IMPORTANT NOTE: Your 500 ml final volume is the total
volume, therefore you need to subtract 130 ml from 500 ml to
determine how much water you need to add the 130 ml of acid to.
500 ml - 130 ml = 370 ml water. Remember, always add acid to
water - NOT the other way round. 

I hope this helps and I'm REALLY sorry for any confusion caused.
It really is simple once you get your head around what figures to
substitute into the equation. Hubby says I should post a blog
about it rather than keep posting emails every time someone asks
the question. I may just do that. Then when the question comes up
again, I can post a link to my blog. But in the meantime, this
will do the job. 

Any questions, drop me an email. 

Helen
UK
http://www.hillsgems.co.uk
http://helensgems.ganoksin.com/blogs/


#10
For ferric nitrate I use 1 cup of ferric nitrate crystals to 3
cups of water. You want the solution to look like strong tea. After
using, decant the spent solution into a plastic bottle with a screw
top. This can be any juice bottle or water bottle, it doesnt
matter. Disposal should be through your towns hazardous waste and
the bottle marked with a date. 

An important addition to Karen’s otherwise complete description.
About that “any old bottle” thing… At the very least, be sure it’s
a bottle that does NOT have a metal cap. Some juice bottles have
metal caps. Even if covered in a plastic, or the like, this is
dangerous. The Ferric Nitrate is much more aggressive than the
original fruit juice, and if it works through that plastic and
starts eating the metal cap, it can generate gas pressure in the
bottle. Eventually either the acid eats a hole in the cap, releasing
the pressure, or the bottle bursts, or something in between… Use a
bottle with a plastic cap. Best would be a plastic bottle actually
intended for strong acids. From lab supply companies, and sometimes
various surplus outlets, you can get nalgene or similar bottles of
polypropylene or nylon, sturdy caps and all, that are strong, acid
proof (or near enough to it), and thus reasonably safe. A flimsy
little disposable water bottle which might burst open if dropped by
accident, is not as safe, even if it’s cheap. And that juice bottle
with a metal cap (Snapple, for example, packages their juices and
teas like that) is asking for trouble.

Peter


#11

Peter is absolutely correct that one must put nitric acid in a proper
container, with a proper cap. I actually had my nitric acid cause
deterioration of the cap–which surprised me as it was the special
kind of cap that is made for strong acids. I noticed, just in time,
before any damage was done, that the cap had split, presumably from
the pressure. I contacted our chemical supply place and got another
cap. The clerk told me that even with the special caps, it is good to
check the bottle of nitric acid regularly, as it is strong stuff, and
should be stored correctly.

Since that time I have been using ferric nitrate—mainly because I
use PnP as my resist, and it does not seem to hold up the the nitric
acid. Also, Nitric Acid is nasty stuff to work with.

Alma


#12
And that juice bottle with a metal cap (Snapple, for example,
packages their juices and teas like that) is asking for trouble. 

#1, good advice from Peter, but I’ll add something even more urgent
and important. The best thing to do is to use laboratory glassware
for chemicals. If you must use household jars and what have you (as
we all do), get a sharpie and write “NO FOOD” on it at least. Don’t
assume… An even better example is our pickle pot, which is a mini
crock pot. It doesn’t have writing on it because it’s on my bench,
but when I change it for a new one I put the pot in the garbage and
break it with a hammer so no one will ever use it as a crock pot…
Do the same with food bottles that had chemicals in them - could
save a life or more likely a case of poisoning…

#2 Thanks, Helen for the quickie dilution method. I have some 70%
nitric I’ve been putting off diluting and I know the other two ways:
molar/molal, which is more than I need, and the good 'ol 1 part to 3
parts, which is a bit less than I need. Thanks a lot!!!


#13

Use any plastic bottle and top that has stored CocaCola. I figure
any plastic that can store sweet malted battery acid will take spent
ferric nitrate, LOL.

-k


#14
Thanks, Helen for the quickie dilution method. I have some 70%
nitric I've been putting off diluting and I know the other two
ways: molar/molal, which is more than I need, and the good 'ol 1
part to 3 parts, which is a bit less than I need. Thanks a lot!!! 

My pleasure John.

Somebody did, however, email me a couple of days ago saying that I
was right with regard to the dilution, but that in his experience
the acid bath got weaker with use. I replied saying of course it did
as it’s a one way chemical reaction in which the reactants are used
up. It later occurred to me that maybe there was some confusion, and
that perhaps he thought my “final concentration” referred to the acid
concentration after a period of time and some use. It does not. It
refers to the acid concentration immediately after dilution, before
any use.

So, to try and make it simpler:

Final concentration x final volume = original concentration x
original volume

where “final concentration” is the concentration of the acid AFTER
dilution with water (what you are aiming for), “final volume” is the
volume of the acid (or whatever) solution AFTER dilution with water
(it includes the volume of acid added (original volume) AND the
volume of added water. “Original concentration” is the strength of
the acid (or whatever) you purchased, and the “original volume” is
the amount of that acid you add when diluting it to arrive at your
desired concentration. So, the amount of water to add is the
DIFFERENCE between the “final volume” and the “original volume”.

I hope that’s clearer than it was - and a little more truncated.

Helen
UK
http://www.hillsgems.co.uk
http://helensgems.ganoksin.com/blogs/