Sumi Only

Is Kuru Sumi only good for Outlining?
Or is it good with shading or coloring as well?
Please explain.
Thanks
I recently became a tattoo fan and wanting to get a tattoo but im still in the process of finding the right artist to tattoo me. so while im waiting, why not ask around bout inks and stuff to know if the artist i choose uses the right stuff.
So, im not trying to a tattoo artist nor a scratcher.
Just wanna know stuff.
Is it bad to know stuff even though your not really gonna use it?
Kuro Sumi is good ink all the way around, but it can take a financial toll. I find Eternal inks to be just as good, but slightly less expensive.