# Adventures in Etching



## Ed McDonnell (Dec 29, 2012)

I was cleaning up the shop today to try and get a "clean" start on the new year.  Part way through my cleaning I discovered a box of equipment / supplies I had accumulated last summer when I was planning to explore metal etching.  That discovery ended the clean up effort and launched me on a mission  to etch metal.  Ultimately I plan to attempt a cloisonne / champleve / gullioche hybrid.  But baby steps first.  I need to actually prove I can eat controlled cavities / holes in metal with acid.

As I was taking a break from designing my masterpiece on the computer, I stumbled across the following information on etching with a "renewable" alternative to ferric chloride.  It would be great to not have to deal with disposal of toxic waste.  Thought it might be of interest to others here:

Etching with Air Regenerated Acid Cupric Chloride

I don't recall Brad having mentioned this alternative in his experiments.  Then again, there are a more and more things I don't recall with each passing day.  So, I'll apologize in advance if this is old news.   I intend to do a side by side comparison of copper and iron chloride etching and see for myself (unless somebody replies to this post with a definitive "don't bother, it won't work").  I'll report back on any positive results that may be realized.

Ed


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## trapper (Dec 30, 2012)

My worry is the chloride....... it indicates chlorine gas to me which i understand is, lets say not nice. Brads the guy to advise but i strongly suggest good ventilation and maybe fume extraction


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## Ed McDonnell (Dec 30, 2012)

Hi Trapper - I had noticed the chorine gas, but I wasn't overly concerned.  But only because I'll be doing everything outdoors.  One of the advantages of living  where I live is that it's pretty nice outside most of the year.  And the trade winds are almost always blowing which provides natural ventilation.

Besides the chlorine gas, I'm not comfortable with bubbling acid indoors where any mist that escapes could settle on tools that I would prefer not to expose to acid.  So there's more than one reason for me to do this outside.

I figure it can't be much worse than working with the chlorine that I add to the pool each day.  Having once gotten a whiff of chlorine when the breeze unexpectedly shifted while pouring it out, it definitely is not something you want a lot of around you.  I'll probably wear an appropriate chemical mask (and goggles) when I am working with any of the etching stuff.

Ed


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## BradG (Dec 31, 2012)

Found Cupric have you :wink:

Well first things first, the chlorine gas isnt an issue to be concerned over with Ferric. Afterall, Ferric Chloride contains chlorine.. hence the chloride in its name. It becomes an issue with both of these chemicals when a current is passed through them in an electrolyte bath for instance, which will then create chlorine gas as a byproduct. This is why we do NOT use salt water as a conductor in an alectrolyte bath, as that is sodium _Chloride_. Chlorine gas is generated when replenishing cupric however

One point to clear up here, is that what you are looking at is an acid - and quite a potent one too... albeit it sounds like you are familiar with hydrochloric acid with working with pools.. you dont want this stuff in your eyes, eye protection gloves and apron are a must.... though needless to say its not a dangerous chemical to work with , when taking the relevant safty precautions.

Ferric chloride on the other hand is not an acid, it is a corrosive. It does not atomise and dissipate around the workshop like you are envisioning indoors corroding all your beloved tools and machinery... the cupric however, will. a fume extraction hood, or as you say outdoors. though wind shift should also be considered. (Reminds me of an old friend of mine which was brewing tear gas in his back garden and the wind shifted :smile-big:he learned a valuable lesson the hard way)

You are dealing with an acid which can be carried in the air, which will irritate any mucus membranes, respiratory tracts and eyes. This is afterall, what chlorine gas would also do, as when it makes contact with water, it reverts back into acid.

Seems like a good experiment to me  Will be good to see how you get along with it. There is no reason whatsoever as to why it wouldnt work, though may just take a little more time to etch.

Be sure to familiarise yourself with an MSDS before doing so
http://nj.gov/health/eoh/rtkweb/documents/fs/0532.pdf


Copied and pasted:

*A Note on Air Regenerated Cupric Chloride Etching: **A Safe Alternative?*


Some print studios have recently adopted cupric chloride etching systems in favor of ferric based ones. The cupric chloride etching process originates in the electronic industry where expensive safety and containment equipment is utilized to conduct this process safely. But the benefits of this method are in its very economical use of chemicals (some of these are recycled during etching), not in enhanced safety. The method involves the use of large amounts of hydrochloric acid, chlorine, and chlorine gases in its operation, so it should be classed as acid etching not metal salt etching. Even the electronics industry is currently debating whether the significant hazards of chlorine gas exposure inherent in the process are worth the risk. 

Chemistry of the Cupric Chloride Etch: "...However, the practical difficulties of using Chlorine for replenishment, not just the actual safety issues, but more importantly, the perceived problems, in the heavily legislated, risk-averse, environment of today, make the use of Chlorine not very common, even in the largest facilities. It should be noted here, that much of the perceived safety of alternate replenishers is just that, perceived. Any replenishing system in use today, if the controls do not function correctly, can generate significant quantities of Chlorine gas. Chlorine gas can, of course, be very dangerous to any form of life, even to chemical process engineers." 


"A safer substitute for etching copper plates is ferric chloride (iron perchloride). This forms acidic solutions so should be handled accordingly, but does not have the dangers of handling concentrated acids. Ferric chloride solution might cause minor skin irritation from prolonged contact.
(c) Copyright Michael McCann, Center for Safety in the Arts 1992"


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## Ed McDonnell (Dec 31, 2012)

Hi Brad - Thanks for the info Brad.  Your point on wind shifting is well taken.  I wouldn't want to end up etching the BBQ grill or anything else on the patio.   I may move further out into the yard when I give it a go.

I keep a jug of acid for adjusting the pool PH.  Many years ago, I made the mistake of storing the sealed jug in my shed with my gardening tools / equipment.  A week later everything metal in the shed had a nice thick coat of rust.  Full safety gear for me.  

I have two resons for using the ferric chloride in the backyard:

1) I live about 12 miles from the Ocean.  Even at that distance, the salt mist in the air corrodes the metal fixtures on the east facing side of the house.  I don't want to take a chance on any trace of ferric chloride finding it's way out of the vat and onto anything else in the shop.  

2) Between all the tools, equipment and in process projects that are stuffed into and scattered about the shop, I couldn't find a sufficiently large clear flat surface to set up the etching gear. :redface:  So, a table in the backyard it is.

Ed


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## BradG (Dec 31, 2012)

parklandturner said:


> Hi Brad - Thanks for the info Brad. Your point on wind shifting is well taken. I wouldn't want to end up etching the BBQ grill or anything else on the patio. I may move further out into the yard when I give it a go.
> 
> I keep a jug of acid for adjusting the pool PH. Many years ago, I made the mistake of storing the sealed jug in my shed with my gardening tools / equipment. A week later everything metal in the shed had a nice thick coat of rust. Full safety gear for me.
> 
> ...


 
If you are going for acid based etchants then i would really be recommending outdoors too  As youve said gives you more room to play anyway.. Though I sense you may have fallen for a common misconception which i hear very often, as i live at the beach too. (about half a mile from the ocean)

The air around our homes is not salt rich from the sea and leaves us no more worse off to rust than anywhere else in the country. sort of. By this what i mean, is that many people think that water from the sea evaporates, condenses on their metal items, and rusts. What they forget is that when water is evaoprated from the sea or anything for that matter, any impurities, including salt is left behind.. only carrying pure clean water. This doesnt account for the fact that you DO get salt water spray carried from the sea in the wind over long distances which gives us all this extra rust in seaside towns :biggrin: :rain::rain::rain:

Though it does emphasise the point, that by having a vat of a corrosive liquid (not acidic, as acidic create corrosive gasses, not air) by the corrisive liquid simply evaporating into your shop, wont cause any of your things to rust . you would need strong winds in your shop to carry a spray off the surface of your tanks to coat your machines to cause an issue


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## Ed McDonnell (Dec 31, 2012)

Hi Brad - With the ferric chloride set up, it's not evaporation that concerns me.  It's the use of a stream of air bubbles to agitate the mixture while etching.  I wasn't very clear on that. 

I don't have a magnetic stirrer and was planning on using an air stone hooked up to an air pump to keep things moving about in the in the etching tank.  That seemed likely to put some ferric chloride into the air.  If etching is something I end up doing regularly, I'll likely invest in better equipment that would alleviate most of my concerns about etching (with ferric chloride) indoors.  

I really want to have a go at it today, but I seem only able to steal the odd moment away from family / holiday stuff today.  Maybe tomorrow.

Ed


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## BradG (Dec 31, 2012)

as and when you have time :wink:

I look forward to seeing your results


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## frank123 (Dec 31, 2012)

BradG said:


> parklandturner said:
> 
> 
> > Hi Brad - Thanks for the info Brad. Your point on wind shifting is well taken. I wouldn't want to end up etching the BBQ grill or anything else on the patio. I may move further out into the yard when I give it a go.
> ...



One consideration:  Interacting breaking waves and wind produce aerosols of sea water that is not evaporated before carrying the salt minerals into the air as fine particulates.


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## BradG (Dec 31, 2012)

frank123 said:


> BradG said:
> 
> 
> > parklandturner said:
> ...


 

im presuming you didnt see the line i typed which read :


> This doesnt account for the fact that you DO get salt water spray carried from the sea in the wind over long distances which gives us all this extra rust in seaside towns


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