 First attempt at etching mask
Following on to my Adventures in Etching thread, here's where I stand at the moment.
I decided to use photosensitive film to create the etching mask. I spent a day creating an incredibly intricate design and then decided something simpler was probably a better bet for a first attempt. So, another day to create a simpler, but still suitably challenging design with all the elements efficiently laid out and connected to allow for etching without losing any parts in the bath. I printed my artwork out on inkjet film. Next I adhered the photo film to the brass (2" x 2" x 0.005"). The artwork on the inkjet film went on top of the photo film (which was adhered to the brass) and the whole package was set out in the sun until it turned what I judged to be a suitable color of blue (about a minute in 2:00pm sun). Next the exposed brass / photo film combo went into a sodium hydroxide solution to dissolve the unhardened unexposed parts of the mask (what shows brass in the pictures). The part on the left was my very first attempt. It came out pretty good. I must have gotten overconfident with the second part on the right because the mask is missing in places where it shouldn't be missing in the lower right. Not sure if I didn't get the brass clean enough, or didn't give the film enough sunlight (it was about a half hour later when I did this one) or any one of a dozen other things I might have done not quite right. I decided to put the actual etching on hold until I decide whether I want to try and patch up the mask on the piece on the right with some paint or something (using my tiny 2 hair brush) or whether I'll strip the mask and start over. For someone experienced with circuit board production, this whole process would probably be a walk in the park. For me, it seems messy, fussy and complicated. I'm sitting here thinking that spraying a coat of paint on the brass and using my cnc to mill off the paint to create an etching mask may be a whole lot better approach. But I'll give photo etching one more attempt before giving up on it. As to what you are looking at in the pictures. After etching, everything brass would be gone, leaving only the blue lines. The blue photo mask would be stripped off revealing the brass detail preserved underneath. That's the plan anyway. If you are familiar with cloisonne, you can probably guess how this might be incorporated into a pen design. At this point I'm only prepared to do Nouveax Cloisonne which involves the use of colored resins instead of vitreous enamels. Stay tuned for breaking developments..... Ed | |
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 01-03-2013, 03:05 PM | #2 (permalink) |
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Finding a good mask can be elusive. I've tried with the transfer masking films designed to be printed on a laser printer, nail polish, adhesive films, duct tape, enamel paints, and oil based markers, all of which were only marginally sucessful when galvanic etching brass with a copper sulfate solution. Usually the etching process was too long for the mask to hold up. Even tried the CNC thing to scratch away the paint. Getting fine detail was the hardest if not impossible for me. Will be following and hoping you come up with a breakthrough.
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| 01-03-2013, 03:24 PM | #3 (permalink) |
Hi Bruce - With these practice runs, I'm just setting up to etch from one side.
With the photo film or the cnc, I should be able to get accurately registered masks on both the front and back of the metal. That would allow me to etch from both sides and cut the time in half, significantly reducing the potential for undercutting. The metal I'm using right now is 0.005" thick. My detail lines are 0.020" wide. Based on my research to date, that should be more than enough margin of safety to preserve my detail. After I actually try an etch, I'll see how my research matches up to reality. Ed | |
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| 01-04-2013, 01:54 PM | #4 (permalink) | |
Rather than masking another piece of brass, I decided to just go ahead and etch what I had. I etched the piece with the good mask in Ferric Chloride. I etched the piece with the failed mask in copper chloride (HCL + Hydrogen Peroxide + CU).
Experiment 1: After an hour in Ferric Chloride, the piece was etched through (0.005" thickness). Took a lot longer than I expected, but the results are adequate for what I plan on doing. It's not terribly messy, but I plan to continue doing it outdoors. Knocking over a bottle of the stuff on my workbench would be a nightmare. Picture is below. It looks a little ugly, but it will polish up nicely when I use it. I tossed a pen into the picture to provide scale. Next time I'm going to do a couple things differently: 1) I am going to photo mask both sides so that I can etch from both sides. That should speed things up. 2) I am going to mask a lot of the waste brass. No point in dissolving more metal than I need to. My Ferric Chloride will last a lot longer that way. 3) The photo masking worked really well on the one piece, but I would like to find a simpler more foolproof method of masking. I'll keep trying the photo masking, but I also intend to explore using my DOL or my CNC Router to create a mask Experiment 2: After 30 minutes in the copper chloride, the piece was barely etched. I could detect a faint whiff of the nasty fumes as I was standing there. Decided it was not worth it and aborted this experiment. Next step is to incorporate the etched brass into a sample pen barrel. Ed Last edited by parklandturner; 01-04-2013 at 01:56 PM. | ||
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| 01-04-2013, 02:34 PM | #5 (permalink) |
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Having tried this before with varying degrees of success, let me offer a couple of things:
Ferric chloride is slow. While it works, it can take long enough for you to get some serious undercuts. (it will etch sideways under your mask) It might be better suited to a solid brass barrel. Electrochemical etching is probably going to work better for what you are trying to do. Very similar to what you're already doing, just add a battery charger to move things along. Might change your speed from 1 hr to 5 minutes. Muriatic acid and peroxide should also work faster, is less expensive and you can recharge it by adding back some oxygen. (shake the bottle, add a little more hydrogen peroxide etc.) Plus you can get everything you need at the grocery or hardware store. Muriatic acid is used to clean stone, brick and the like. It is a diluted form of hydrochloric acid. Home Despot, Lowes, Ace .. all of those places will carry it. Hydrogen peroxide is probably in your bathroom already. Check the medicine cabinet. If you know someone with a laser engraver, try using a polyester film for a mask. (bumper sticker material?) Draw out your design and convert it to a vector. Apply the mask to both sides of the brass, engrave one side and then flip the brass and the vector image to do the other side. Weed the image, leaving the mask on the parts you want to keep. Office supply stores (Staples, office Max) should have bumper sticker or adhesive polyester. Avoid vinyl, as lasing vinyl releases chlorine gas. This is not only bad to breathe, the smoke will condense and turn into hydrochloric acid and eat away the metal insides of the machine. This can lead to the loss of a friend with a laser.. 
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Last edited by NewLondon88; 01-04-2013 at 02:35 PM. |
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| 01-04-2013, 03:30 PM | #6 (permalink) |
Hi Charlie - My "copper chloride" experiment was done using Hydrochloric Acid (= muriatic) + hydrogen peroxide + copper. As I understand things (and I could be understanding incorrectly) the combination of the acid, peroxide and copper results in a copper chloride solution which is what does the etching. In any case, besides it not working very fast for me, I did not like the fumes coming off the stuff and don't think I'll be exploring this approach any more.
Etching a brass barrel would be fine for a Champleve type result using resins instead of vitreous enamels, but I ultimately want to try enamels and brass is not a good base metal for that. My current approach of etching thin brass sheet could easily transfer to copper sheets and would be compatible with the vitreous enamels whenever I get up the nerve (and moolah) to give it a try. Sadly, I don't know anyone with a laser. What I really need is to get friendly with someone with a CNC plasma cutter (or whatever would cut fine detail in metal). Don't see that happening though. The electrochemical etching sound interesting. I'll have to do some research on that. Thanks for the feedback! Ed | |
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| 01-04-2013, 05:00 PM | #7 (permalink) | ||
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as the ferric..) Yeah, the first time will give you more fumes, too. Since you were working with acids and etching, good ventilation was assumed. After the first batch, the smell decreases. It should have worked fast, though. I found it 10x faster than the ferric etching. I also used an aquarium stone and air pump, which means I didn't have to keep recharging with the peroxide. (at 60-90% water, it just dilutes the etchant and slows it down) The peroxide will oxidize the copper and wear out. You can recharge it with more peroxide, or just get the oxygen back in there with the aquarium pump.. it is the acid that does the etching.
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with the addition of the electro part. The brass sheet is your anode, and while you're etching with chemical, you're also dissolving the brass anode with electricity. There's many people here with lasers. That small a sheet of brass can go in the mail in a small envelope. And I think there's a couple of members with lasers that can cut metal, too. Mine won't even cut me a break, lately.
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Last edited by NewLondon88; 01-04-2013 at 05:02 PM. | ||
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| 01-04-2013, 07:20 PM | #8 (permalink) |
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Newlondon, im not "having a go" so to speak...
But i wouldnt be recommending putting a current through any chloride, be it ferric chloride or copper chloride, due to the amount of chrloine gas it pumps out.. if you are going down this route then you would be best off using dilute sulphuric acid or another electrolyte which is not chlorine based... EG no salt wwater (sodium chloride) or anything else.. Its great to see people are following in my footsteps with the etching,... but i would hate to see anyone exposing themselves through risks as a result of it. Furthermore, Ferric is a faster acting etchant than copper Chloride. perhaps something else was going on when you found 10x speeds with copper chloride, though this is not the expected result.
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