I have plenty of small marks on the acrylic after its removed from the mold. It looks like it was caused by dirty/dusty mold, but mold is clean and smooth. I attached images of mold and acrylic.
I am thermoforming clear and dark acrylic sheets thickness of 3/32". My mold is made of aluminum with almost mirror finish ( I tried few different finishes, but same issue). I heat my acrylic sheets to 250F and mold to 120F
Can anyone help me what I am doing wrong?

THANK YOU VERY MUCH.

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