Having an issue with eyelash shaders, So if I use diffuse or PBSDF with color set to black both sides of the roughness scale cause issues. Low roughness and the lashes look nice and black like they should  but now they are glossy and reflect light back. High roughness and the lashes no longer reflect but now they turn dull grey and don't "pop" like lashes would with mascara.

My solution is to use the same trick I use on eye pupils: Use no shader at all, total blackness in any light condition. Have a look.

W10, Ryzen 5 1600x, 16Gb,RTX2060Super+GTX980, PP11, 11.3.740