So, my very first etch wasn't originally intended to be an etch....

[EBK]

This is a fun result.
Was attempting to do a masked electroplating of copper onto a Hammond 1590K430 (zinc alloy version of the 1590B) using a solution of copper acetate and peracetic acid (hydrogen peroxide and vinegar), after apparently inadequate research.   Although the electroplating worked well on some coins, the solution proved too corrosive for the zinc alloy enclosure.
The results aren't bad though. 

[marcelomd]

Nice! Came out very sharp.

[Fancy Lime]

Yepp, looks really nice. Bummer though, the chemist in me would have appreciated a copper plated zinc enclosure for a Brass Master. A lot. Do you know if there is a way of actual brass plating that is DIY-feasable?

Andy

[EBK]

Yepp, looks really nice. Bummer though, the chemist in me would have appreciated a copper plated zinc enclosure for a Brass Master. A lot. Do you know if there is a way of actual brass plating that is DIY-feasable?

Andy

Brass, being an alloy of copper and zinc (as you already know), requires very careful balance of a lot of variables to plate directly, i.e., you don't want one metal outracing the other.  I was going for more of a copper over zinc plus fire equals brass approach.

[Kipper4]

Nicely done.
Just fill the etch with gold......

[EBK]

Nicely done.
Just fill the etch with gold......

I actually have some brass inlay powder that I was planning on using with a conventionally etched aluminum enclosure.  I'm going to give it a try on this one.  So, you aren't far off.

[EBK]

Here's a slightly better view.

[deadastronaut]

came out great...looking forward to the brass inlay.

will look the nuts. 

[EBK]

A sneaky swap out here:  This one is a regular aluminum 1590B.
Anyway, I'm learning that inlay powder, when set using CA glue, is very hard to work with.
It's much harder to sand than aluminum, but you can't be overly agressive or it pulls out, mostly due to the surface edges once the excess glue becomes very thin.

I'd call this a partial result. 

(difficult to capture well in a photo because both the aluminum and brass are shiny...)

I'm not giving up yet.

I'm going to see if a skim coat of Envirotex mixed with brass powder will let me fill in the gaps.

[thermionix]

Reminds me of a Raging Slab song.

[Marcos - Munky]

So your first etch is way cleaner than a lot of people's 3th/4th etches attempts (mine included), and you said you got that result by accident .

Very beautiful!

[EBK]

So your first etch is way cleaner than a lot of people's 3th/4th etches attempts (mine included), and you said you got that result by accident .

Which is precisely why I didn't complain when the electroplating didn't work out. 

Very beautiful!

Thanks!

[EBK]

Well, the inlay powder mixed with epoxy worked.....
But, then I learned that using acetone to clean up after my sanding was a bad idea.  Totally removed both the epoxy and CA portions of the inlay.  So, plan D is the winner, metallic gold spray paint:

(That's still the aluminum enclosure.)

[duck_arse]

awwww, spray paint? I wanted the metal junk to look that good. it does look very nice tho.

that lower right pot-hole - full or empty?

[EBK]

awwww, spray paint? I wanted the metal junk to look that good. it does look very nice tho.

I'm going to do some more research and give the electroplating another go on the zinc enclosure.

that lower right pot-hole - full or empty?

You lost me. I'm a brass is half full kind of guy.

[EBK]

I cannot for the life of me get my zinc alloy enclosure remasked.  I sanded it down to give electroplating another try, used acetone to thoroughly clean the surface, and tried the exact same PnP Blue transfer technique I had used to great success before (the original pic in this thread and the pics of the aluminum enclosure were my very first and second toner transfers, and both came out perfectly).  Now, all I can get are variations of this (this is probably my 8th failure in a row now):

Anyone have any idea of what I may have inadvertently changed to ruin my luck? 

[Fancy Lime]

What changed? Your enclosure material! The surface of zinc is very different from that of aluminium. In fact, there is no such thing as an aluminium surface in a breathable atmosphere, it immediately (not "very quickly" but literally instantaneously) oxidizes to form a thin layer of aluminium oxide (Al2O3, aka corundum or in its gem-incarnations as ruby or sapphire, depending on color caused by trace elements). This aluminim oxide has a micro-roughness to which toner sticks very well. When you etch, the etching agent eats through the oxide layer and can then attack the metal itself.
Zinc on the other hand oxidizes much slower and produces an oxide with very different qualities. Zinc oxide coatings are usually very smooth. I strongly suspect that the toner just does not stick to th zinc all that well because of that.

Try this:
Run a fingernail across the box surface of both enclosures. This is a very sensitive way of determining surface roughness. Does the aluminium enclosure produce more drag than the zinc enclosure. I would expect the aluminium to feel a bit like the unglazed part on the bottom of a coffee mug and the zinc enclosure more like the glazed surface of it. If that is so, then that is indeed the problem, I think.

Did you use hot or cold transfer? Have you tried the respective other method? Some people use alcohol soluble lacquer: spray a thin layer on the box, apply the image as usual when the lacquer is still wet, press, wait, remove the paper, clean with alcohol. Never tried it myself but may help overcome the lack-of-stickyness problem.

Hope that helps,
Andy

[EBK]

Thanks, Andy.  I have only one problem though with what you wrote:  The toner DID stick just fine to the zinc the first time.  That's how I got the first and second enclosure pics in this thread.  That is the zinc enclosure after masking with a toner transfer (hot PnP Blue transfer method) and etching (albeit accidentally).

I should add that giving up on directly electroplating and simply re-etching this zinc enclosure is probably the way I'm going to have to go, based on some further research.  The problem is that any acidic plating solution is going to eat the zinc before it gets plated.  It seems I would have to use a cyanide-based plating solution, which is out of the question for DIY.

[Fancy Lime]

Right... I forgot. Hm, anything you did differently? Cleaned more thoroughly now? More/less time between sanding and transfer? Different end grit?

As for the plating in general: The cathode should not dissolve. If it does, something is wrong, most likely the voltage is too low. However when plating something noble (copper) onto something much less noble (zinc) a whole bunch of problems related to kinetics and ion mass balance in solution become significant. Therefore it may be worth trying to first plate the whole box with something intermediary (nickel is probably best in this case) and in the second step plate the nickel plated box selectively with copper. You wrote that coins plated ok, what material were those?
I found some nice tutorials for exactly that:
http://www.instructables.com/id/High-Quality-and-safe-Nickel-Plating/
http://www.instructables.com/id/High-Quality-Copper-Plating/
And good idea to stay clear of cyanide methods unless you have a proper fume hood at your disposal and absolutely know what you are doing!

Andy

[EBK]

The coins I plated were a US nickel and a US quarter.  Both are made of cupro-nickel, but in different copper-nickel ratios.
Regarding the zinc dissolving, it readily dissolves in the solution even with no voltage applied.  I was afraid of applying too high of a voltage for fear of merely adding a flaky burned crust of copper, which would simply wipe away easily when done.  Adding a nickel plate to the zinc beforehand makes sense, except the DIY method still uses vinegar to create an acidic solution, which will still happily eat away at the zinc.

The copper plating method in your second link is pretty close to what I used, by the way.