Usually it is the media used in a sand blasting device, but here is a video of using garnet sand to make a matt surface by hand. https://www.instagram.com/p/B0CWBbFleQC/
Usually it is the media used in a sand blasting device, but here is a video of using garnet sand to make a matt surface by hand. https://www.instagram.com/p/B0CWBbFleQC/