Could you tell me what it is and why it happens

When I engrave in a mirror acrylic, a black dot appears on the plate. Could you tell me what it is and why it happens.

It could be a few things.

It could be flashback, though that usually only happens near a cut line.

It could be a problem with your artwork, especially if this is a raster and not a vector.

It could be physical scratching from your crumbtray, are you engraving the front of the mirror or from the back?

Things to wonder:

Is it always in the same spot?

Did you make the art file yourself? (sometimes downloaded art can have strange artifacts)

Can you upload the art file for inspection? (it’s ok if you can’t for any reason, but it does sometimes speed up troubleshooting if someone can look at the actual file)

Let us know a bit more about what you’re up to and we may be able to narrow it down.


The engraved edges have a very distinct quality, basically what you’d expect to see if a short pulse of laser energy hit the mirror foil. It’s not cleanly removed, the edges are melted. But the black spot is different. Its edges are sharp with no evidence of melting. I would say the black spot must have been there before you did the engrave and you just didn’t notice it. IMO that black spot was not caused by the laser, it’s a physical chip…

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I agree.

The laser didn’t make that mark. It’s an imperfection in the coating on the material, or a mark from handling.

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