i was wondering if the taper in the glass has anything to do with it. but it seems sudden rather than gradual, so likely not.
for glass, i’ve tried it all the ways i’ve heard and the best i’ve found so far is to use dish soap. it settles fairly even unlike paint methods, nothing to pick off like tape or wet paper.
i’m usually hitting glass or crystal that’s flat (awards), but i’ve found that stronger (higher power) didn’t get me better results, just different shapes of fractures. with the soap i go fast ish (400mm/s) for my machine at 30-40% (of 80w).
try it with the dish soap and see if you get more consistency.
yep. over a smallish area i’d get a bit on my finger and very lightly rub it on. for a larger area i’d squeeze a few drops onto the thing i’m engraving and then rub it around with my finger.
you are going for a thin film, but don’t worry about it being thicker. the soap likes to level out on its own.
Tempera paint is thick. Most likely variations in the paint coating thickness causes the variances in the power of laser hitting the glass after it finally blasted through the paint, especially with a diode.
I don’t let the soap dry. I put it on, ensure its all over whatever I’m hitting, give it a second to level out and go. I’m using a co2, not sure how a diode behaves with glass.