The glass of my SPIN 900 | 1200 | 1500 is sooty – why?

Bioethanol from other manufacturers can cause the glass to become sooty or black for various reasons. Therefore, please only use our original höfats bioethanol liquid fuel, which burns without soot or odour. SPIN 900 | 1200 | 1500 has been specially tested and approved for use with this fuel – for safe use indoors and outdoors.
To the original höfats liquid bioethanol