Good morning what a beautiful piece! I have a question for you about san mai.
I tried my first san mai yesterday with a railroad spike and coilspring. I tried what I've heard is the "traditional technique" so hot cut a well in the spike and inserted a piece of high carbon. It seemed to go pretty well for my first time, I tried a heat treat in oil first but it didn't seem to harden. I may have heated the oil too much so I did a second heat treat in water, that got the file to skate.
My question is, do you need to temper san mai?
Sorry to high jack, I just saw an opportunity to ask someone who might be able to help.
Thanks.