If I remember correctly it’s the copper dissolved in the etchant that’s toxic if you dump it more so than the ferric chloride itself. Seems like that would be true regardless of the etchant.
Ferric chloride will stain and potentially damage steel plumbing fixtures and pipes as well.
True…dumping acid down the drain is rarely a good idea. My understanding though is the dissolved copper is highly toxic to the aquatic wildlife that ultimately end up swimming in the stuff dumped down the drain.
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Umm… Salt, water, and a D cel battery work just fine to etch a lot of things, no acid needed…
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I really like using CuCl. There is a good explanation of how to get started on this Instructable (view at your own risk; lots of marketing ahead). I have some and could share it with you if you get the right plastic container for acid. I forget the plastic type but can look when I get home. The beauty of this method is that you never throw it out. You can regenerate the etchant by bubbling air through the solution with a fish tank pump; it changes colors so you know when you are done. You only need muriatic acid (a.k.a. hydrochloric acid, HCl, or pool acid, I have some of that too for my pool that I could share), hydrogen peroxide, and copper. I choose to dissolve copper wire to get started because I don’t etch that many boards but you can also just start etching boards to create the etchant. The only downside is that you really want a fume hood when “regenerating”. It takes hours and produces some fumes. Regeneration is only needed after quite a few boards. The last trait of this method is that over time, as copper is dissolved, the solution needs to be diluted with more HCl and water. Good news is it is like a friendship cake; easy to divide the solution and share. Maybe a partnership with the Science Committee would make sense if others want to use this method.
Yeah, copper sulfate is no good for aquatic life (or humans for that matter).
Copper(II) sulfate can be disposed of by adding iron, forming Ferrous(II) sulphate and elemental (inorganic) copper. The result can be solidified with some kitty litter and disposed of in the trash.
http://www.gcsescience.com/r5-metal-displacement-reactions.htm
I’ve used that method with good results as well. Much less expensive than buying the usual PCB etchant. There’s even muriatic acid in the chemical cabinet at DMS.
An interesting fact is that copper sulfate sprays are commonly used in organic farming as a fungicide!
Recycling!
Hmmm. Not so sure I’d spray this on my tomatoes 
Can anyone tell me from what type of place I would purchase ferric chloride?
Fry’s and Tanners have it as well.
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Hi All
I need to start doing some (brass) photo-etching of my own for fine-scale model building. I intend to use the Micro-Mark Pro-Etch Photo Etch System https://www.micromark.com/Micro-Mark-Pro-Etch-Photo-Etch-System_2.
My question: what type of CAD or Illustrator software do we have available at DMS that can be used for fine detail flat pattern layouts?
We have:
- the Adobe Creative Suite (Photoshop and Illustrator)
- Inkscape
- Autodesk/AutoCad (I think)
- DraftSight (facility modeling, but supports CAD
plus some various 3D modeling tools such as Fusion 360 and SolidWorks. When I create photo-etching patterns I tend to design in vector paths and then stroke/fill once I have the vectors completely done. I can get very precise results that way. Of course, the problem with using the Adobe Suite is that it isn’t a CAD program so you have to manually size/scale everything.
What software do you have to print your pattern onto your transparencies?
Thank you for the reply, John!
I need to rely on the Adobe, Inkscape, Autodesk and DraftSight at the DMS: I do not have my own software.
My understanding is that most modelers have the artwork professionally printed? I do not know what software is needed to transfer the art to the transparencies.
I am a model railroader. I have some brass diesel and steam locomotives that I am wanting to super-detail thru the creation of new brass photo-etchings. Much of the detail is double-sided, usually 1-2 layers of etch including cut-thuand kerfs so that pieces can be bent and formed.
Can we speak on the phone or meet up at the DMS?
Fusion 360 is free to hobbists. Take classes at DMS and can use at home.
I successfully use the Adobe products. You should be able to also. You can save the resulting image to a high resolution jpg and print it onto the transparency using any software that will print a jpg. I don’t recall whether the kit contained transparencies - if it did, they were inkjet transparencies and I only own a laser printer. FWIW, inkjet will usually give you darker black.
I seem to recall printing mine at (Office Depot?) but wasn’t entirely thrilled with the result. The blacks weren’t as opaque as I would have liked. I printed them commercially only because I had little to etch and it was cheaper to print a couple transparencies than to buy a box of laser transparencies.
Be prepared to do some experimenting to get what you’re looking for. Use the precision of a chemist and keep detailed notes regarding times, temperatures, exposures, etc. Also keep in mind that the thinnest line you can etch all the way through the material is half the thickness of the material itself. So if your material is 0.010" thick, the thinnest line you can etch completely through is also 0.005". (OK, in reality it’s probably a hair more, like maybe 0.006" …) This is well within the capability of even home printers.
Remember to put registration marks on your artwork so you can line up the transparencies for both sides of the etching.
Also, try to avoid large black areas on your artwork because that will deplete your etchant faster. (Black is what gets etched away). Use a “cut through line” and let the rest of what you don’t want just fall into the bottom of your etchant tank. Here’s an example:
EDIT: Go to the dollar store and buy yourself a cheap bucket and a funnel or two that you can use with chemicals. Fill the bucket with really hot water and let your ferric chloride bottle sit in there until you are ready to use it. Warm etchant etches much faster. You will also use the bucket for rinsing.
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You can print highly opaque transparencies at home using inkjet transparency sheets and UV blocking ink.
You can get these supplies along with refillable ink cartridges at multiple online sources, where they’re usually sold for making screen printing negatives for photo stencils. I personally like using inkowl.com for our printer at home.
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Thanks for posting the picture example, John!
It looks like you made up 4 negatives for 2-levels of etching. The first being the cut thru and the 2nd being a controlled depth for detail. On the 2nd pass, how do you go about re-aligning the metal with the transparencies? Did you also etch registration marks onto the metal?