Please HELP, wootz etch not working very well

[katana]

Hi, could someone advise me on etching wootz, as I seem to be doing the right procedure....but without the results

I am using ferric chloride granules mixed with distilled water (approx 150g to 150ml of water approx. 5oz to 1/3 of a pint).

Before applying the etchant, the blade was cleaned with solvent, and then warmed using the gas 'rings' of the cooker. The etchant was also heated to a temperature of a 'hot coffee'.
Immediately the blade/etchant was hot enough , the etchant was applied by brush to one side of the blade.
I continually applied etchant as it started to 'dry out', however, several attempts, the last time I left it on for 30 minutes, has not really brought the 'pattern' out. It definately appears to be wootz but it seems I am not getting the 'bite' I need. The mixture is slightly more concentated than is advised on the etchant packaging (250 g to 300ml )

What am I doing wrong ? Has anyone had this problem before?

Thankyou
David