Warangan query

[SidJ]

Hello
I have a query on traditional warangan application I hope you can help with. I can get quite a strong colour appear when brushing on the solution but when I rinse it under water the dark colour simply washes away and the blade is left bright silver again. Does anyone know why this is the case and why the colour does not stick and what I could do to address the problem? It is incredibly frustrating to say the least to experience elation at seeing pamor but then for crushing disappointment as it washes away under tap water! I am using an entirely traditional recipe and technique.
Thanks