Hi Sellam You might check at places like stained glass supply stores or places the do beveled glass. They have polishing compounds that are designed to be used with a buffing wheel. The technics I used are designed to end up with a surface that is smooth to less than 1/8 wavelength of light. You don't need anything like that for a screen. Most telescope stores don't have supplies for doing mirrors. I mail order my supplies from places like Newport Glass or William-Bell. Check with places that sell and repair window glass. If they don't have anything there, they'll at least know where to get it. Dwight