Black TRANSLUCENT acrylic ? Fiber engraving

[BaronPork (Ignas K)]

What a hell i’m looking at here ? 100w JPT M7 MOPA laser.

Customer brought black acrylic to engrave. Did tests on some random scrap, dialled it in more or less, put customers acrylic on - nothing, not even a spark. So i start running more material tests, only for all of them to end up on the laser table under the black acrylic.

Took a flashlight - lights through green…

WTH ???

[BaronPork (Ignas K)]

The material test left some sort of sub-surface crazing, but cant see anything at all on the surface…

[BaronPork (Ignas K)]

It is Perspex branded, black , so i didnt even think it would be something seethrough for 1064um.

Tests i ran on random black/glitter(two sided) and Altuglas 5mm black, to the right the weird Perspex. I cut the parts myself on my CO2, smelled like acrylic sheet and all that…