Basically, baby’s bottom is a problem with the nib in which the tines come together and form a concave structure instead of a flat surface where the nib meets the paper. This concave structure looks simular to a baby’s bottom, hence the name. Since the part of the nib that delivers the ink isn’t really touching the paper, the result is bad starts and inconsistent ink flow.
The best and easiest way to fix baby’s bottom is to send your nib to a qualified nibmeister to resolve the issue. There are many online tutorials that demonstrate how to fix this yourself, this is fine but if you are not experienced in modifying nibs, you might end up doing more harm than good. If you are going to attempt it, do it on a cheep nib you don’t care if you damage.Kirk Speer