Hi Teoh,
Thanks for the review - very useful. I have a petrel pocket brush pen and find fine lines easier on the pentel colour brush pen though coverage when inking in is less precise and lines less defined. I am interested in the Kuretake no.8 and no.13 though. I thought I had read though on Cult Pens in the UK that they are compatible with Platinum cartridges so the Platinum carbon cartridge should work for waterproof ink shouldn't' it? Regards