1_Do 95% of the final look before using finger stones.
On a honyaki you need corser stones like max #3000 and a very soft uchigumori in order to whiten the ha.
Too fine surface is very counter productive so, a suita of middle hardness or a #8000 synth won’t never give you clean results.
On a knife with clad you may use about any kind of finisher for preparing the blade.
If you want mirror core and hazy clad, choose a middle-hard/ hard Jnat with fine grain.
The harder the stone, the more metallic and „nervous“ the mirror will look like. For this the core needs to be particularely clean.
A softer stone will give a smoother and whiter mirror.
A clean clad makes the job with finger stones easier because you can let appear more life and details.
Anyway the caracteristics of the Jnat used are only important on the core, not on the clad.
Finger stones don’t erase deeper scratches so work as clean as you can on your benchstones.
2_ choose the right hardness
. the softest and coarsest on the ha for a honyaki.
Honyaki can’t never be scratch free polished so you have to hide the scratches the best as you can.
Softer finger stones whiten the ha and produce a more visible hamon.
. the finest with high hardness for the ji on a honyaki.
You need some contrast in color and texture. The surface is very soft so harder finger stones are not as problematic as on the ha.
On clad, the finger stones used depends on the hardness of the metal and the contrast /effect with the core you are looking to achieve.
3_shape them right
Flatten them and glue them to some strong paper.
Thin them until they are thin like a credit card and make the crack around a round object in order to make them flexible.
Cut them small. Too large finger stones wear unevenly.
Generally, the finer and harder the finger stones, the the smaller and thiner they are.
4_polish them smooth
a corse #200 diamond stone will give good results on a soft finger stones but some harder ones need to be polished finer like #600 – 1000 grit.
5_use fresh water with sodium bicarbonate in order to prevent from rust.
6_Apply little pressure and short strokes.
7_Be careful to let the shinogi line crisp and to not round it with your finger stones.
8_A long session is much more productive than many short sessions
Give yourself a goal and stop when you reach it.
10_Use your eyes.