[Roland_M]

Hello,

my etchant is very mild. The strong contrast comes from the scanner. The pattern can be easily removed within a few minutes with sandpaper 1500 or 2000. If i would use a strong etchant, this would destroy the micro details.

I use sodium persulfate (fine etch crystal) and a special technique, to bring out the finest details. It was a long way of experimenting. Compared to nital or nitric, sodium persulfate produce sharper details.

1: polish the surface up to a sandpaper grit of 3000.
2: etching with 20% Sodium persulfate (20Gramm (0.7 oz.)/ 100 mL distilled hot water) and a cotton ball until the result satisfy me
3: polish the surface again with sandpaper 5000 and 7000 or steel wool 000 + 0000 + Micro Mesh 8000
4: etching again with 7.5% Sodium persulfate (7.5 Gramm/ 100 mL distilled hot water (~50°C))
5: polish the surface with Micro Mesh 8000 and 12000 to a mirror finish (in this case).

The complete pattern is only visible under direct sunlight (the best way), halogen light or with the scanner.

Try it out, you will be surprised. A nice side effect, Sodium persulfate is a very effectice rust remover. The color contrast is not so good, FeCl is better, but after some bad experiences i will never ever again use FeCl on antique steel because it creates a kind of moon surface full of pitting under the microscope even when used with low concentrations (~5%).

Thanks for the pictures and comments. I also think, it is a three layers construction with hard steel in the middle, like japanese san mai.

Kind regards Roland