That weird salt water etching

Ah, salt water etching. A technique I use very often. Just to remind you (or introduce you to, if you've never heard of it) what it is: it's an etching technique, in which the traditional acids or mordants are replaced with salt water an weak electric current. The piece to be etched is submerged in over-saturated saline solution, and attached to positive charge. Scrap piece of metal is submerged as well, attached to negative charge. It's an electrolytic process.

Etching... see the bubbles? It's a negative terminal

 As with any etching, you need some kind of resist, and from what I read, finding one that works is trickier with this process than with traditional etching. Permanent markers, for example, are useless, as they wear off way to fast. I find nail varnish to be the best resist. Acrylic paint also works, but is more prone to coming off the etched piece. Nail varnish generally last throughout the whole process.

Lately, I've been working on bracelets. And I encountered problems I never had with this technique before. Depth of etching varied not only from piece to piece, but also within one piece alone. The texture of etched parts also varied. It's weird. And I don't get why is this happening. All pieces etched for the same amount of time, 3h. I always etch for this amount of time, as this gives (usually) a really nice, deep etch.

If I ever before had any problems, it was with too shallow etchingt, if I used solution so saturated with copper, that it wasn't as effective as before. But this is to be expected.

I, however, never had a piece that etched through. That is, until recently. I had to discard one project, because there were holes in some places. Again, the same sheet gauge, the same amount of time. Weird.

The first, slightly botched attempt at a cuff

So this was the first in the series of bracelets. Remember I was working on a wolf cuff? I didn't like the result, forgot about it for a while, and then decided to have a second go at it, with a bit different design. I would like this one if it wasn't for the wolf you see here, and another one closer to the end of the cuff.
Anyway, what I really do like about this cuff, is its texture. See here:

Texture of the first wolf cuff.

The texture of the etched parts is gorgeous. The etching is deep, texture is grainy, and just really nice. It looks like this on the whole cuff. This cuff etched for three hours, in freshly mixed saline solution.

Now, after seeing etching results, I decided to have another go, as I felt I can't sell this to anyone. So I made another wolf cuff.

The second wolf cuff, with better etched wolves

Here, I also wasn't 100% happy with the etching, but decided this one is good enough to put up for sale. I guess other people liked it better than me, as it's already sold. Anyway, I liked the image on this one, but the texture wasn't as nice. And uneven to boot. On one end it resembles the texture on the first cuff, on the other end, the etching is shallower, and the texture is... not as interesting.

Texture on the second cuff

This picture shows the texture around the middle of that cuff. You can really see the difference, but it still is somewhat similar to the first cuff. But near the end...

Texture on the second cuff, near one end

 The grain is sparser here, not to mention those... lines? grooves? I have no idea what caused this. As I mentioned, etching here is shallower, but this is not that weird, considering that it etched in already used solution. What is weird, however, is that the etching doesn't have uniform depth: it's deeper on one end than the other. It also etched for 3h.

The next cuff I made was the raven cuff.

Raven cuff

I'm awfully happy with etching on this one. However, that one is weirder that the last. It etched in fresh solution. For three hours, as is the case with all of them. And the etching is a lot shallower than on the first wolf cuff. And it also differs in depth on this one! I don't get it!
Look:

Texture on one end of raven cuff

Here, it's grainy, and of decent depth. Not as nice as on the first wolf cuff, but pretty nice. No grooves, lines, or any other weird stuff ( and yes, I know I use the word weird a lot in this post).
And the other end?

Why is this happening?!?

A lot shallower, not as grainy, but still uniform texture. If anyone have any idea as to why this may be occurring, I sure would like to know!

And that's not all. After the wolf cuff sold, I decided to make another wolf cuff, with different design of course. So I cut the strip out of the same copper sheet I used for all those bracelets, put it in solution, etched it for three hours, cleaned it... and almost had a fit. Why? Because of this:

A hole!!!

Holes! Holes in the metal! Ugh!

And not just one at that!

I didn't bother with cleaning it properly, there was no point. But, what is, again, weird here? Of course, it etched through only on one side! The other one looks like this:

The end without holes

It's etched to about the depth I was expecting, texture is bizarre, true, but overall it's what I thought I would see after removing the nail varnish. Well, that one went to a certain box, and waits there until I finally decide whether I want to try delft clay casting or not. It would be shame to waste all that copper, after all.

Oh, and I also had one more unpleasant surprise. Remember titanium pieces I'm working on? Well, I made copper parts, cut them, painted them, put them into etching... and one etched perfectly, and the other one etched through, and I had to start over. And they both were etching at the same time!
So frustrating!

As I mentioned, I have no idea why this started happening. It doesn't make much sense to me. The set up is the same. The salt I'm using is the same. The source of electricity didn't change, and nor did the voltage. It's just so weird. Anyone has any ideas?

Till the next time!
Kasia

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