The Problem: an uneven paint finish
I earlier showed that I was giving the Hercules Model G a rather aggressive polishing. The reason for that is the bike's frame was over painted with black paint at some point, creating an uneven surface. The black paint the individual used was not bad quality, but the application was sloppy. The paint actually appears to have been considerably better than the over-paint that had taken place on the fenders. I was able to strip the fenders back to the level of original paint, then touch them up.
The paint on the frame is tougher. What I found is that I could get the frame over paint to match the rest of the bike, but I needed to "level" the surface so it matches. Hence, I used a mixture of 2000 grit sand paper followed by Scratch Doctor polish to level off the surface. This left some spots shiny, some a bit dull, and some actually worn through (where the paint had chipped off). A test revealed the original paint could not be fully restored because (a) the over paint had bonded hard to it and (b) the original finish was fairly badly damaged on the frame.
A solution:In order to remedy that problem, as well as make the bicycle parts consistent, I employed the "thinned paint rub" method I previously used to touch up the fenders. The idea here is to use the existing over paint, which actually used decent black paint. However, it was applied with a brush so it was uneven. A sand/polish/paint wash will solve it.
(see http://bikeshedva.blogspot.com/2013/04/removing-paint-from-bicycle-fender-and.html. )
The method was simple: take a rag, then apply some paint thinner to a particular area of the rag. Next, take matching paint and apply it to the area where the thinner is. When mixed properly, the paint should become impregnated into the rag. The thinner you previously put on there pulls the paint into the rag fibers by thinning the paint. You do not want it where you have big globs of paint on the rag surface. You want it where the rag absorbs both paint and thinner.
Finally, rub the paint onto the part in long strokes, being careful to keep the layer applied thin and even.
I prefer this method for filling minute scratches and pits, as well as balancing out a finish that is somewhat uneven. In this case I wanted the "wash" of paint to seep into the low spots on the finish without leaving a thick layer like you would get with a brush.
Note: this is only an alternative method!
The method I have described above, is only one alternative. If the finish you have is particularly thick, you may be able to actually just sand and polish it all the way down to level without having to fill using the wash. On this bike, I had a particularly nasty combination: an over-paint from a previous owner, combined with uneven application of paint as well as chipping of the original finish to the extent it could not be just brought all the way back to original.