Cement Stains on Window Glass

I think muriatic acid can get this off, but check first. Wear gloves and face guard.

tooth paste on a wet cloth. tooth paste has fine abrasives that should polish the etching marks off.

Working in a cement works I often had to use vinegar in the water to wash my car.

I hope he gets lucky. I've seen the alkali from the concrete physically etch the glass.

Boraxo maybe or gypsum from the hole you knocked in the drywall or silica sand

Concrete is a very strong alkali, glass can be etched by a strong alkali stripping atoms from the surface. The only cure is to polish out the etch by buffing with very fine abrasives. Someone suggested jewellers rouge, which will work. This search tree shows many methods.

Jewellers Rouge to polish glass

Apply Sulphuric acid or caustic along with a detergent. Glass can with stand both and not cement. Start with dilute to med concentrations and also on reaction time criteria,

Phosphoric acid is another safe alternate. Even a toilet cleaner should be workable.

Do spotting tests & proceed. Use cotton buds to apply.

WOW Z-12 awesome it even removes SBS (stubborn bird spots) this stuff sounds great.

It appears to me that some people think there is still some cement left. The cement is gone, and the alkali in the cement (which is very alkaline, Ph 13 or more) strips the glass matrix by removing surface atoms. This is gone, leaving an etched surface, like the inside of a light bulb. The only way to remediate this is with a classical polishing with a very fine polish that is also harder than glass - jewellers rouge is this. A small amount is dabbed onto a wet cloth and you rub the glass with a firm back and forth, changing the axis as you buff and keeping it damp. It takes a while, but it is doable.

Hello

One can use muriatic acid or brick cleaner , contact you local concrete supply company or home improvement store for products and info. Remember (Safety First)