After cut residue from bottom of the cut

Your dear laser-cutting noob here.

I hopefully have an easy question to answer.

While my cutting works fine, cuts are really good using about 225mm/min using 95% laser power(1 pass), I am getting under the cut on the element ‘a residue’, and sometimes it looks a bit wet.

I was wondering if there’s anything I can do to prevent it? How does it occur?
If not is there some kind of post process I can do to help cover it?

I’m attaching few simple pictures how it looks like.

The material I’m using is this:

It could indicate that your material is not raised enough or lies directly on a metal or ceramic surface. The laser blows the burnt material which, due to the temperature condenses on machine bed.
Raise your subject with small blocks or punk spikes, it works fine for me, also you can use masking tape on the top and bottom, use the wide tape it’s easy to work with. For cleaning, you can use technical alcohol or acetone.
Hope it helps you.

That’s a good and valid point. Definitely it lays on another wood surface, that’s something I didn’t think of.
Many thanks. I will try to raise it and see how it goes. Many thanks!