I saw this handy and frugal tip on www.permies.com and wanted to share it.
I haven't tried it yet but an experiment of half my windshield with Rain-X, the other half with potato is on today's agenda.
Here is what Dan Hamilton blogged on permies.com:
Environmentally friendly way to get Rain-X effect on your windshield.
1.) Cut a potato in half.
2.) Hold the exposed (cut) portion of the potato against the windshield and wipe it all over your windshield. The starch in the potato will act as an invisible barrier between the windshield and the rain.
3.) Repeat as necessary.
I have used this before and it worked as well as Rain-X, however I am not a big fan of the Rain-X effect. For those that do this is an inexpensive and environmentally friendly way to get similar results. I searched for information on what is in Rain-X and found special polymers. The vagueness of the description makes me wonder.
Montana Mobile Oil & Lube
Like Dan, I was intrigued by just what's in Rain-X. After a bit of Googling, I discovered it's "complicated" - with myriad chemicals, including alcohol and silicones; then add a few processes just short of nuclear fusion to make your windshield shed water like an oiled duck.
I just made my life more complicated by needing to KNOW FOR SURE if that potato will measure up, or will Aquapel end up being my dream water repellant while my ever-faithful Rain-X goes the way of progress. Rain is expected tomorrow. So I'm off to the windshield experiment for two contenders (only because I don't have Aquapel with me) - it's Potato vs Rain-X.
Do You Have a Preference?