Ok for those that have read my "new etching job" and wonder how one does stuff like this, well here or some tips.
You have to remember you are working with electricity in the form of DC current. You want to be able to control where you plan on etching and not have large areas charged with pos or neg so you do not short out in places that you don't intend on etching.
Doing something like this is really no brainer, set your stencils into location, then what I do just to be safe is mask off everything else. This cuts down on the chance for shorts, plus it will help to keep the etching solution for getting all over your slide or whatever you are etching. The solution has salt and vinegar with a little water mix and is very corrosive and left on bare steel, it will start to surface rust if not removed soon after etching.
Doing these Madalon's brings up another challenge.
First how do you hold them for etching and how do you make a solid connection without getting solution all over.
Sence these are aluminum the corrosion from rust is not a problem but still I don't like the solution dripping all over. So, to solve these problems I mask off everything that will touch the Madalon including the back of the Madalon too.
My stencil does not cover the whole Madalon, so I used some fingernail polish to cover bare spots.
Fingernail polish works great for small areas, it acts as an insulator to protect from shorts and solution form getting all over. This tip I got from We4ponxyz (thanks buddy).
Another thing that works with fingernail polish is building up a well. What I mean by this is building up a small wall around your etching spot to hold a puddle of solution. The reason for this is a puddle of solution make good contact for the etching process, just keep adding a layer of fingernail polish over and over till you buildup about 1/8th inch to hold your puddle.
You can see where I put the red wire in the vise. I made a small bare spot on the Madalon for the positive without connecting it to any other thing that might conduct current. All this made this a safe set up with a small chance of an accidental short.
This was the first time I tried to etch aluminum it etches different than steel. It is more like a heavy sandblasting than etching. Steel cuts fast at 10amps where aluminum seems to be slower.
If you have any question just post them, I will help if I can.