Trisodium Phosphate effect on Glass

[cranky]

Can anyone tell me how to remove a stain on glass caused by trisodium phosphate?

 

[Boomerang]

cranky
Acording to Schweitzer, borosilicate glass is resistant to trisodium phosphate.
Stable under normal temperatures and pressures. Incompatible with strong acids, strong bases, strong oxidising agents, strong reducing agents.
Your stain is either surface or trapped sub-surface in micro-cracks.
Don't fancy your chances but consider soaking with dilute HCl

 

[hacksaw]

buffing wheel with suitable abrasive, you are dealing with surface damage that can obly be removed by polishing or suitable annealing.