Time To Make New Probes

I need a new probe, Probe 9 having been put through the wringer a bit. So this time I'll try to quantify and document this a bit better. I also need to find an alternative to nitric acid, so I'll wrap that all into one project. The following sequence was taken of a wire (now Probe 10)  as I etched it in 5% salt water for 20 seconds at a time. Between etches the wire was washed with water, sprayed with isopropyl alcohol, then force-dried with cool air:

 I kept the magnification constant, so any apparent thinning or tapering of the wire is real.