I've used Ray Dobbins' paint-fill technique with enamel in the past with acceptable results (below - the DT shifters incorporate enamel and go to a different bike), but would like to find a process that recreates those crisp lines using acrylic rather than enamel as acrylic can be undone much more easily.



Getting a crisp, smooth edge between the paint and surface of the part is of course the trick. With enamel it's easy enough to apply the paint, let dry for a bit, then cut the lines with a tightly folded shop towel/rag lightly soaked in mineral spirits before the enamel is fully cured, paying close attention to the edge. Not so with acrylic - the paint likes to peel back off the surface of the part, pulling adjacent paint back in the process. ...Imagine pulling a single cheesy chip off a plate of nachos...if that's an acceptable analogy.

Below are the results from the test of an acrylic process. I found that getting a med/small brush saturated with paint and letting drops spread across the part's surface works much better than trying to spread the paint across by pushing the brush - gravity smooths the surface better. The acrylic on the parts below sat for 48+ hours as a first step (I had only planned on 24). After that the paint was plenty dry I was able to start pulling off all of the excess. I found the best way to cut the edge between the paint and surrounding surface was to hit the edge with either a finger nail or wooden toothpick and work out from there. Applying a very light layer of mineral spirits across the surface seems to help.