When I want to test an ink, I have two options either I buy or trade a sample or I buy a full bottle. I would probably just get the bottle because it is not THAT expensive.
What I want is something bigger than a sample, but smaller than a 50ml bottle. 10 or 15 ml would be perfect. Because a small sample is never enough for me to do a proper test. I like to test it in many different pens in order to get the full picture of how a ink behaves. But the problem with the full bottle, is of course to get rid of it, if you don’t like it or don’t see yourself using it all.
The reason I try to always test a ink with as many pens as possible is because to use a ink with a finer nib versus a broader one or a dry pen vs wet pen is very different. The colours are different. And the dry time is different.
Some inks look better with a fine line, while others look much better with a big wet one. And some inks are just unusable with a wet nib because you have to take a nap while you wait for a page to dry