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Etching with ammonium persulphate


#1

Hi everyone at Orchid @ Ganoksin

Could someone advise me if Ammonium Persulphate is a good chemical
to use for etching on copper and brass?

If yes how to go about it?

If no, what other chemicals would be recommended?

Thanx,
Eva


#2

Hi Eva,

I use Ferric chloride for etching on brass, it is a traditional
home-use circuit board etchant.

Best,
Melissa


#3

Don’t know how it will work on brass but it does work on copper.
Keep in mind it is a strong oxidizer and can react with other
materials to cause a fire so be careful with storage and handling of
it.

Jim
James Binnion
James Binnion Metal Arts


#4

An electronics hobbyist friend of mine recently was raving about
muriatic acid (hydrochloric acid) and hydrogen peroxide, both store
variety, not hte highly concentrated stuff. it is mixed, and used as
an etchant for copper. Although of course it is corrosive, it is not
as toxic as ferric chloride.


#5
An electronics hobbyist friend of mine recently was raving about
muriatic acid (hydrochloric acid) and hydrogen peroxide, both
store variety, not hte highly concentrated stuff. it is mixed, and
used as an etchant for copper. Although of course it is corrosive,
it is not as toxic as ferric chloride. 

What makes you think that muriatic acid is less toxic or hazardous
than ferric chloride, just because you can buy it at the local
hardware store? Muriatic acid is technical grade hydrochloric acid,
this means it has some contaminants in it making it less pure than
the reagent grades of the acid. It is terribly corrosive and the
vapors are extremely hazardous. You can do severe damage to your skin
eyes and lungs in a heartbeat if you do not treat this stuff with
great respect and the proper safety precautions. On the other hand
ferric chloride is the hydrochloric acid salt of iron. It is made by
dissolving iron in hydrochloric acid, while it is also corrosive it
is no where near as dangerous or toxic to handle as muriatic acid. If
you splash a little ferric chloride solution on you you will probably
only notice the stain it leaves on your skin, if you get some of that
muriatic acid on your skin you will know about it immediately as it
will severely burn the skin.

The main reason the electronics hobbyist are using something other
than ferric chloride is it has gotten hard to find at local hobby
electronics stores due to hazmat storage issues and mail order
suppliers must add very high hazmat shipping fees. A quart of ferric
chloride could end up costing $60-$70 with these fees added in.

And BTW one of the main contaminants in muriatic acid is iron which
means it contains ferric chloride.

James Binnion
James Binnion Metal Arts


#6
The main reason the electronics hobbyist are using something other
than ferric chloride is it has gotten hard to find at local hobby
electronics stores due to hazmat storage issues and mail order
suppliers must add very high hazmat shipping fees. 

Actually, you can buy it by the gallon from print makers supply
shops (Try Graphic Chemical and Ink in IL) and they told me that it
does not require hazardous shipping.

Elaine
http://www.CreativeTextureTools.com


#7

I was researching the conversion of Hydrochloric to Ferric recently.
I was digesting pure iron in 34 percent solution for a week with
frequent agitation and mild heat. The result was not anything
suitable for etching. I ended up with Iron chloride II as a sediment
in the bottom of the vessel. I was after the sediment, but I wondered
why the fluid did not have the characteristic color of the Ferric
Chloride when I was done? The acid was pretty much dead cetainly not
any good as an etchant. After some quik searches It seems that
Hydrogen peroxide needs to be added to complete the (violent)
conversion. I don’t need any Ferric chloride etchant so I have not
tried it. I just sifted out the sediment to be added to a browning
formula I have been playing with.

The addition of Hydrogen peroxide to acids was a new one to me, but
apparently if there are any metals such as copper or iron disolved
in the Hydrochloric a new fresh acid will be formed (i.e. FC) when
you add the Peroxide. There are byproducts from this in the form of
nasty gases though so I have read.

BTW, if anyone needs Ferric Chloride for etching it can be had in
dry granular form off ebay quite cheap. I picked up 32 ounces of dry
Amonium persulphate from Frys electronic store for $16. I find it
useful for etching certain things.

Radio shacks still have FC occasionally, but when their out of it
they always claim its discontinued. If you keep checking it
eventually shows up again. Its very sporadic and their reasons for
not having it are just as random. Best as I can tell from 25 years
of looking in radio shacks is that they get random shipments that are
sometimes years apart. When they run out of whats on hand it is
"discontinued" until they happen to get some more… Regards,

Patrick Hastings
Taganearts.com


#8

I just ordered the Iron Perchloride Crystals crystals for making a
ferric chloride solution from Graphic Chemical. I ordered 10 pounds
of crystals, and I shipping was around $10, so there definitely
wasn’t hazmat shipping charges.

Jason


#9
Actually, you can buy it by the gallon from print makers supply
shops (Try Graphic Chemical and Ink in IL) and they told me that
it does not require hazardous shipping. 

The last gallon I bought (earlier this year) did have hazmat
charges. I certainly am no expert in government regulations so I have
no idea on the correct shipping regulations.

James Binnion
James Binnion Metal Arts


#10
What makes you think that muriatic acid is less toxic or hazardous
than ferric chloride, just because you can buy it at the local
hardware store? Muriatic acid is technical grade hydrochloric
acid, this means it has some contaminants in it making it less
pure than the reagent grades of the acid. It is terribly corrosive
and the vapors are extremely hazardous. 

Well, Isaid it was less toxic, not less hazardous. I was referring
to the iron content,which can cause permanent liver and other organ
damage, and according to many sources can be absorbed through skin.
Long term exposure in small amounts could be particularly insidious.
It’s also fairy corrosive, though not as corrosive as muriatic.
Also, the muriaticnacid sold in hardware stores is generally 40% or
less concentration, so not the same as for example as 100% pure
(fuming) hydrochloric acid. BTW, I’m well aware that you can buy all
sorts of dangerous things at a hardware store. You can also buy
ferric chloride at Radio Shack.


#11
I just ordered the Iron Perchloride Crystals crystals for making a
ferric chloride solution from Graphic Chemical. I ordered 10
pounds of crystals, and I shipping was around $10, so there
definitely wasn't hazmat shipping charges. 

That is because it is dry. There is a big difference between shipping
liquids and dry chemicals in the way they are regulated. I meant to
bring this up in an earlier post. If you are comfortable with mixing
your own then you can easily buy ferric chloride in its dry form and
just add it to water. Tho get consistent results you will want to mix
it for a particular specific gravity not by weight of crystals and
volume of water. To do this you will need a hydrometer. But if you
are willing to experiment a bit you can just mix by weight and volume
and then adjust to get the right speed and quality of etch. I have a
some of the premixed circuit board etching solution that I adjust by
adding powdered ferric chloride when it slows down.

James Binnion
James Binnion Metal Arts


#12
I just ordered the Iron Perchloride Crystals crystals for making a
ferric chloride solution from Graphic Chemical. I ordered 10
pounds of crystals, and I shipping was around $10, so there
definitely wasn't hazmat shipping charges. 

I went to their website and looked at the material they are selling.
First I am fairly certain it is mislabeled, it is Iron Chloride or
Ferric Chloride not Iron Perchloride. I do not believe that there is
an Iron Perchloride and certainly it is not a current usage for
describing FeCL3. Second they note right in the text that it is sent
as a hazardous material that is what ORM-D means. The reason you do
not pay an additional hazardous material charge is that it is being
sent as a consumer item. The ORM-D
(http://en.wikipedia.org/wiki/ORM-D) classification means it is in a
form and or size that is acceptable for shipping under this
classification. This classification allows shipment of hazardous
consumer items that are deemed to be small enough in volume that
they will not present a major problem if there is a spill or accident
during shipping.

James Binnion
James Binnion Metal Arts


#13
Well, I said it was less toxic, not less hazardous. I was
referring to the iron content,which can cause permanent liver and
other organ damage, and according to many sources can be absorbed
through skin. 

Yes you can be poisoned by too much iron but it is a major component
of your blood. Like anything else it is all about how much you are
exposed to. In our use the likelihood of getting anywhere near toxic
levels is nil, unless you do something really stupid like drink it.

Long term exposure in small amounts could be particularly
insidious. 

Could be? based on what, again you have a large amount of iron in
your body so adding small amounts over a prolonged period of time it
is going to do what?

It's also fairy corrosive, though not as corrosive as muriatic. 

That is the whole point isn’t it, you are corroding away the metal
when you etch it.

Also, the muriaticnacid sold in hardware stores is generally 40%
or less concentration, so not the same as for example as 100% pure
(fuming) hydrochloric acid. 

There is not a 100% hydrochloric acid in liquid form, hydrochloric
acid is a mixture of hydrogen chloride (a gas) and water. It is very
difficult to buy HCL in higher concentration than 36-40 % even when
purchased from chemical supply vendors. That is because it is very
hard to keep the gas in equilibrium with the water and it just
evaporates away rapidly.

The only difference between hardware store muriatic acid and what
you pay big bucks for as reagent grade HCL from the chemical supply
is the amount of tramp materials in it like iron and other metals.
The concentrations of hydrogen chloride are basically the same.

James Binnion
James Binnion Metal Arts


#14
Well, Isaid it was less toxic, not less hazardous. I was referring
to the iron content,which can cause permanent liver and other
organ damage, and according to many sources can be absorbed through
skin. 

Just how toxic “iron”, specifically as a chloride might be,
especially in small amounts is a matter of degree and amount. After
all, iron is an essential nutrient/mineral within limits. Most
people need at least around ten milligrams of iron in their diet
daily, and the main acidic componant of stomach acid is dilute
hydrochloric acid (plus lots of other stuff)… Now, the normal
dietary forms of iron are NOT ferric chloride, so it may not compare
at all. But iron isn’t a universally toxic thing. There are various
iron supplements sold to older people or to treat anemia, and a
shortage of iron in the body can be just as bad as too much. Almost
any material in excess can be toxic, even plain water. And iron
overload, if too much is in the diet or body are toxic as you
mention. (And I don’t know how the absorbtion of ferric chloride
would differ from the normal dietary forms of iron) But at least
small amounts are essential and needed in the diet and by the body,
and the body has fairly rigourous means of preserving and controlling
it’s iron resources. Clearly, heavy exposure or actual ingestion of
ferric chloride is not at all suggested or a good thing, and as with
any caustic or corrosive or fuming chemical we use, proper
precautions are essential. But I’d think that the very slight
exposure you might get from normal, careful use of ferric chloride as
an etchant, should not pose an unusual risk of iron toxicity. All
bets are off, of course, if you handle this or any chemical
carelessly. But I’d be more concerned with merely the
acidic/corrosive properties of ferric chloride, especially fumes into
the lungs, rather than iron toxicity. The similar risks with
hydrochloric acid or muriatic acids would seem to be even more of the
same, at least judging by the detectable fumes each of them seem to
emit when used. I find the acids themselves much more annoying and
irritating than ferric chloride, which would suggest to me that they
are the greater risk to my lungs and health if improperly used…

Peter


#15

Ferric Chloride is the same thing as Iron Perchloride. You can
search by either name on chemical supplier websites such as
Sigma-Aldrich. There are evidently a lot of synonyms for FeCl3.

It is a hazardous chemical, which means you can’t ship by air, but
you don’t pay any additional hazmat shipping charges for ground
shipment. That is the important part to me. I really hate paying $30
in shipping for a $10 bottle of chemicals. I used to buy it locally
by the gallon at a electronics supply house, but they closed down a
few years ago. It was more expensive, but available for awhile at
Radio Shack, but it was pretty hit or miss. The price also went up
significantly since the last time I bought it there so it became
more cost effective to order online.

Jason


#16
In our use the likelihood of getting anywhere near toxiclevels is
nil, unless you do something really stupid like drink it. 

If you are careless and get it on your skin/clothes regularly when
using it over a long period of time (due perhaps to thinking it is
not toxic) I don’t know that that is true.Also if you have a liver
that is in any way compromised (not as uncommon as you might htink)
you would do well to avoid it.

Could be? based on what, again you have a large amount of iron in
your body so adding small amounts over a prolonged period of time
it is going to do what? 

Well yes but most of that iron is very securely bound up in the
hemoglobin, it’s not exactly the same.For that matter, your body
also has a fair amount of hydrochloric acid in it, in the form of
gastric juices.If you get that in your lungs it can kill you.

Anyway, my main original point was just that I thought the ferric
chloride was more “toxic”. I dont believe HCL is toxic per se.It is
corrosive to be sure, and dangerous, absolutely.The fact that it is
an integral part of your digestive system says to me that it is not
toxic (i.e poisonous).

Either ferric chloride or HCL can be safely us= ed, and either can
kill you


#17

Yes, I’m not sure you can directly compare toxicity of the chloride
form, as absorbed directly through the skin or lungs into the blood,
to the less direct oral route. Clearly, though it is toxic, it’s not
a problem with reasonable handling precautions. FWIW, I looked up
the ld50 (dose that would kill 50% of subjects it is administered to)
at for example

http://www.jtbaker.com/msds/

and found the following HCL (rat), oral ingestion: ld50 = 900
mg/kgFerric chloride (anhydrous, rabbit), oral ingestion ld50 = 316
mg/kg I couldn’t find the ld50 for the same animal, so I dont know
if rats are much more or less sensitive as rabbits ( I assume they
are reasonably similar). Of course the FC etchants we use are mixed
with water, but even so, a strong solution of FC could be more toxic
than the HCL


#18
Ferric Chloride is the same thing as Iron Perchloride. You can
search by either name on chemical supplier websites such as
Sigma-Aldrich. There are evidently a lot of synonyms for FeCl3. 

Yes you are right, it looks like that is an old name for it.

James Binnion
James Binnion Metal Arts


#19
Yes, I'm not sure you can directly compare toxicity of the
chloride form, as absorbed directly through the skin or lungs into
the blood, to the less direct oral route. Clearly, though it is
toxic, it's not a problem with reasonable handling precautions. 

The major user for ferric chloride by volume in the US is in water
treatment facilities. It is added to drinking water as a flocculant
to remove suspended particulate matter. It is also used in waste
water treatment for the same purposes.

James Binnion
James Binnion Metal Arts


#20
Anyway, my main original point was just that I thought the ferric
chloride was more "toxic". I dont believe HCL is toxic per se.It
is corrosive to be sure, and dangerous, absolutely.The fact that
it is an integral part of your digestive system says to me that it
is not toxic (i.e poisonous). 

I looked up the definition of “toxic” according to the MSDS
Hyperglossary. That definition does not distinguish between corrosive
and “poisonous” properties of chemicals, it’'s just based on the
ld50. So, according to that definition, both HCL and FC are toxic.
It’s a bit of semantics, since we are all in agreement that they are
both dangerous substances.