Yeah I did the HT.
It was clay quenched but the clay was too thin in places which is why it wandered all over.
I soaked it in diluted PCB etchant for 5 minutes after sanding to 800 grit, sanded to 1000 grit, soaked for 1 minute and repeated a few times (with the same piece of 1000 grit paper) then polished with an aluminum wheel polish by hand (edit: no sanding after the final dip in ferric chloride)