This is an easy way to make a hydrophobic coating from products that have been available for decades. It works great!
Cyclopentasiloxane is the component of antiperspirant that functions as the hydrophobic element to this project. While not quite as hydrophobic the commercial coatings like Never Wet and Ultra Ever Dry, it is significantly less expensive and functions well enough for nearly all the same purposes.
The idea for this project was used courtesy of Dan Rojas at GreenPowerScience. Check out his video on the subject here: http://youtu.be/ujEWwUMC5Y4