Need Help! Cleaning Acrylic after engraving / cut

When I engrave or cut, I get this residue that stick to the non engrave section of the acrylic making it lose it shiny surface.

What would be the easiest way to wipe those off ?

I've used water or windex, but it doesn't do much... I basically end up using my finger nail to scratch that residue out, but it painfully a long process.

Hope someone have an idea.

Thanks

Moc