After the nib has been stamped out, there are quite a few further production steps, including engraving, plating with rhodium – for instance, for the two-tone nib of a 149 – and welding the tipping material onto the nib. The tipping material, as we've already mentioned, is usually a combination of various metals from the platinum family. The reason for using these metals is that they have excellent resistance to abrasion (a property which makes them extremely hard to machine, but very good for things like jewelry and watch cases) . The use of such materials for nib tips is essential for creating a pen that can be used for many years and in my own collection, there are pens from the 1920s and 1930s with iridium tips that write just as well now as they did ninety or a hundred years ago. One of the beauties of well-made pens is that, like a good mechanical watch, they seem capable, with care, of lasting essentially indefinitely. Originally, pure iridium was used, which is meteoric in origin, but nowadays alloys allow for better materials control than meteoric iridium.