Hello everybody,
IMHO it is probably a personal preference - at least during the turn of the century.
[[The process described by Jean using salt, sulphur and rice water is used to etch the blade, not stain; but if I'm not mistaken if we drop the salt it will stain. ]] <Edit: The bold part is wrong. Pls refer to post #30 for correction.
To my knowledge the word warangan was already used in Hikayat Abdullah written in early 19th century.
Below is a quote from Winstedt's Malayan Memories 1916. It is part of a dialogue of a Malay keris dealer with Winstedt:
"" So," he said, picking up bundle and cane, " so, I may
leave this dagger with the tuan. And the tuan has got me
that pink arsenic which keeps a blade bright : I want it for
my creese with the damask marks which the knowing call
' the grass-hopper's legs.' "
We can read it here:
https://archive.org/details/cu31924021572106
I think I had read some other reference about Malays staining their keris using warangan in another text that I had forgotten about.
Also, the keris on the cover of this book appears to be stained.