The New Hotness

Applying only two Sharpie colors to the third quadrant of the engraving testpiece produces a more restrained result:

Instead of sanding the surface, I used a paint scraper to remove everything down to the engraved grooves. The scraper in the upper right is a Rubbermaid 54807, which is apparently no longer available. If I ever buy a new scraper, I’ll spring for a carbide blade.

A dirt speck under the plastic sheet can still obliterate the markings, though:

Overall, the results look just like a real slipstick:

The upper scale was engraved at 225 g downforce, the lower at 300 g, with corresponding differences in width & depth.

Seen at higher magnification with omnidirectional light through the microscope, the tick marks have more detail:

The upper ticks are 0.1 mm wide and the lower ticks a scant 0.2 mm wide. Both ticks on the sanded Sharpie sample were close to 0.1 mm, which suggests:

• Scraping removes less plastic
• The grooves have a flat-ish bottom and side walls roughly matching the slightly worn 60° diamond tool

Sharpie ink is, of course, soluble in alcohol:

That’s not unexpected, as I’ve been removing Sharpie with alcohol forever, but it’s worth keeping in mind. I don’t know if spraying a clear topcoat (Krylon FTW!) would provide good sealing with enough wear resistance.