I haven’t worked with acrylic too much, and this is the first time I’ve encountered the streaks seen in the picture below.
This is 1/4" non-PG masked clear acrylic, engraved (from the back) with a defocused beam. Only a few pieces developed these horizontal streaks; most have a consistent, frosted look I was hoping for.
Is this due to too much power? 1000/Full (Pro), 270 lpi, with a focus height of .4 inches.
Any insights you have would be appreciated!
My guess would be differences in the material as I see this from time to time.
That is not “crazing”. That’s just the nature of acrylic for solid area engraves. Acrylic gives you a very “precise” representation of the path of the laser. Turn the design 90º and the lines will be rotated.
You can work around it with higher LPI, or more extreme defocus.
A lot of people float some acetone in the engraved area to even out the appearance. It would probably make it less white though.
Aha, thanks! I haven’t worked with acrylic much, so I’m still trying to figure out its quirks.
Sure enough, I cut a jigsaw puzzle rotated at 90 degrees, and the lines were rotated. Voila.
For some stupid reason, it never occurred to me to tweak the LPI. I’ll try that next.
Nothing stupid about it.
The laser vaporizes material. For many materials, that point is large enough to overlap the adjacent path. Acrylic just allows a much smaller point. So you can tighten up the path spacing, OR widen the point (defocus.)