If there is any 'iridium' tipping, on the IPG nib, smooth it.
The tipping is standard, in I think Bock and JoWo and everyone else that buys the 'iridium' tipping made in Germany or the world uses the same company which makes the tipping.
It's the care factory grinding of the nib that makes the nib smooth or not. Modern smooth tipping was perfected in WW2. Before that it was lumpy and chunks fell off.
In the 20-30's much engineering was spent trying to make the cheapest long wearing tipping possible, often changing from one year to the next with in the same company. Spend a dollar to save a penny. There is a good article on that somewhere.
Over a few decades since the war, a standard of long lasting 'iridium' compounds would have developed, that I doubt improved. Not enough to waste an engineer on. Cheap and good enough.....none ever went best of all. 'Iridium compounds', have always been more expensive than gold. Iridium is not much used any more, too scarce, just here and there a few inches of asteroid dust....wasn't used in the '30's as I remember reading. Other rare earths took it's place.
The question was how can I make a good tipping cheap.....or a good cheap tipping.
So one buys little 'iridium; pellets or dust for the final stage.
Buying rare earths, properly ground, then mixing perfectly is too expensive. Warehouse storage alone makes that impracticable.
At worse it becomes a cheap practice nib.
German vintage '50-70 semi-flex stubs and those in oblique give the real thing in On Demand line variation. Modern Oblique is a waste of money for a shadow of line variation. Being too lazy to Hunt for affordable vintage oblique pens, lets you 'hunt' for line variation instead of having it.
www.nibs.com/blog/nibster-writes/nibs-germany & https://www.peter-bo...cts/nib-systems,
The cheapest lessons are from those who learned expensive lessons. Ignorance is best for learning expensive lessons.