i love it when people find out that you draw it in pen and only one pen colour value ....hey allan i understand you used a bic ...i also use the PILOT and the medium papermate....but here is my question to you have you ever got your hands on BLACK INK PEN that was just BLACK and did not have that blue hued oil that youll see while it drys?
I don't use just BIC®, I use all the brands I can find as they all have something different. PILOTE® PAPER MATE®, GEDDES® Scent-sible ... all king of Brands.
If I get your question, you want to know if I know a black ballpoint pen that stay black with time and not get yellowish like BIC® for exemple !
To know that, you need to test all black ballpoint pen you find and expose them at the sun for a couple of month. I'm a bit of a lazy so I did not do it yet but I used a Pilote® for that commission cause I know that THAT pen is quite resistant to the UV light.