How to engrave methacrylate?

[Hierro]

Hi.
I'm trying to engrave methacrylate but can not get good results. Surely I will be doing something wrong.
The transparent surface around the engraved area becomes opaque and not know why.
I have seen engraved on the Internet with a very good finish , but do not know if it is given a final polish .

Can you help me?
Regards
Antonio

[Thunder Laser -Nolan]

Hi Antonio,
can you post some pictures, then I can see the engraving effect?