If using a font that is highly contrasted (on glass) – meaning the font is thick on one side and thin on the other – then a 0.25- to 0.5-point stroke is necessary. The font size for this can start at just over 1/16″ around 8 points.
When working with small fonts like government warning labels on the backs of wine bottles, the smallest size should be around 8 points (just over 1/16″) using a 0.25-point stroke on the lettering if you are not using the bold version of any font. Bold versions of some fonts don’t need to be touched up.
Learn more about font adjustments for sandcarving.