In these photos I have an inset picture of a the medium tip of a Pilot Vanishing Point. It is about 0.75mm wide (the writing surface is, of course, a little smaller).
First let's take a look at a brown paper bag. This is one from my local grocery. I thought two close-up photos at different spots was worth it for this material.
This material is complex. The fibers are obvious, but their efficacy as an abrasive is unknown. The surface also seems to include other material that might be abrasive. Some folks swear by it, but for my money there are too many unknowns, and graded smoothing materials too readily available, as higher-end nail care products in the cosmetics section if nowhere else.
Here we see the gray 12000 grit Micromesh surface of the ubiquitous gray-white-pink buff sticks. I also have some small sheets of the same stuff, sold by Revell for model finishing.
And the 2 micron Mylar lapping film:
And the 0.3 micron Mylar lapping film used for the highest polish:
The closest thing I personally have used to the brown paper bag is 3M Wet/Dry polishing paper. This stuff is better used for polishing pen bodies, but the 1 micron paper seems good as a late stage step in polishing nib tipping to me, except that the fibers dislodge and have to be flossed out afterwards. You have to be careful to use it lightly so as not to put lateral pressure on your nib tipping (vintage nib tipping can break off if it is exposed to too much side-to-side force). Apparently, it works because the fibers (which probably aren't abrasive at all) are impregnated with a polishing compound. The fibers, which are not tightly packed, probably brush up against the edges of the nib slit like a hungry house cat's whiskers on your pant leg, perhaps taking off small burrs or "micro-mountains".
The following materials are more abrasive, and I've used them for nib shaping and grinding (not smoothing).
Here are the pink 2400 grit and white 4000 grit parts of the gray-white-pink buff sticks.
And here are some of the more abrasive Mylar lapping films that come in the kits that I often buy, the 3 micron and 5 micron films.
And finally, I occasionally use the finest two stones of a Lansky knife sharpening system, though only for grinding, never smoothing. The flat surfaces come in handy for removal of Baby's Bottom or grinding a round nib to a smooth cursive italic. Of course they have to be followed up by smoothing with some of the other materials above.
This is the 600 grit hone. When you use something like this, you have to mean it. Oddly, it doesn't seem to work all that well. I can take material off faster with the coarser grades of Mylar lapping film.
And the 1000 grit hone. This is the one I use for taking out Baby's Bottom. It removes tipping material very, very slowly.
Edited by mhosea, 03 August 2015 - 02:01.