If necessary, let the acid stay on the window briefly to allow it to work through the minerals causing the water spots.
House Selling Tips – Bedford TX House Buyers: There is a stubborn film that is common on exterior windows and is very difficult to remove. You must have the resolve as stubborn as the water spots to get them off, but it can definitely be done. With the right solution and a few tools you’ll have your windows gleaming like they were new in no time. The spots come from hard water caused by sprinkler systems, water from your hose if you have hard water, or from runoff when it rains or snows.
First, you must purchase a gallon of muriatic acid. It can be found at most hardware, big box home improvement, or some grocery stores. The cost is just approximately $5 per gallon. This is caustic and toxic so it is dangerous to handle without gloves and precautions. Always have fresh running water available nearby in case you spill it or get it on your skin.
“At any time in the process if the acid water spills on anything other than the windows, be prepared to flush the area with water until thoroughly rinsed off.”
The tools you’ll need include a brush mounted on a pole with which you will apply the acid. Have a bucket to mix the acid with water. A squeegee will be handy when you are finished to remove all moisture from the windows, allowing them to dry clear and streak free. Gather your tools before you get started.
Put about one part acid to 2 parts water in a bucket being careful not to allow the acid water to splash you or anything around it. At any time in the process if the acid water spills on anything other than the windows, be prepared to flush the area with water until thoroughly rinsed off. It’s a good idea to wear protective goggles and gloves while you are performing this task.
Dip the scrub brush into the acid water solution and apply it to one of the windows. Scrub the window with the brush and allow the acid to work on the hard water spots. As the spots disappear you’ll notice that the brush will glide more easily over the window. If necessary, let the acid stay on the window briefly to allow it to work through the minerals causing the water spots.
Rinse well including the window sills and anywhere else the acid has dripped as it is caustic and can remove the paint. Move along to each window until you have crystal clear windows throughout the house. Go back to each window and clean as usual using the squeegee to finish it off. You can do this with each window as you go along if that’s easier.