I was showing my knife maker neighbor how to make an etch and saw a couple things he did wrong that hasn't been mentioned yet. In no particular order:
Keep the contact surface between the stencil and the knife dry, in other words, no etch liquid left from your last test. Too much liquid where it doesn't belong lifts the stencil, gives a fuzzy edge and a halo or dark marks where the current follows the liquid.
Don't press down hard, a light touch will do fine. Too hard and you press out the liquid.
The stencil has to be flat on the steel. This isn't easy on a hollow ground, but it can be done.
Clean your stencil between uses by using DC (removes metal) on etch liquid moistened wick pad with a gounded piece of metal. (Like you are trying to etch the wick pad)
Your etch pad shouldn't be dripping wet, but it has to be wet enough to conduct the electric current.
Tape the stencil down so it doesn't move at least two sides and four sides if you have the patience. Remember, flat matters. Use plastic electric tape or blue painter tape. Typical masking tape gets wet and will etch through leaving a halo around your stencil if it is small. I use quality blue painters masking tape.
Nuetralize right after you etch (baking soda/water mix if you don't have nuetralizer), if you don't rust shows up in a few days. Nuetralize and clean your stencil when you are done or it gets crispy and cruddy in a hurry.
Now can someone will tell me how to spell nuetralize?