It is very hard to avoid getting mixed up about the sizing of these pens, that’s hardly surprising as the manufacturers do themselves too !
The sizing of these fineliners is pretty arbitrary & a 0.1 micron is much larger than a 0.1 uni for instance.Some manufacturers are talking about the tip diameter like micron ,while unipin are talking about the actual line width.
The finest hairline you can get on ANY fine liner (or pen) is the copic 0.03 BUT the line is not very black (because there is so little ink put down.) & it stops working at all after a single drawing or two ,even when used with a most sensitive hand & on the smoothest bristol board surface – they have pushed the design perimeters too far & it is just not worth the money or hassle I’m afraid.
The 0.05 copic still has a very fine hairline, is a good black & the tip lasts as longer than any other fine liner.
You will not get a finer lined pen not in fine liners nor dip pens, the 0.05 Unipin fineliner is very fine & lasts well with the advantage that you can use it at a lower angle than the copics.
Those two are as fine as you will find – Believe me I’ve wasted enough of my money on this holy grail quest of the finest line !
If you really want to use super fine lines the secret is to work at a lager scale with these above pens because the truth is that a lines fineness is relative to the thicker lines around about it :wink2:
Mike