The sealant question was more about glass sealant. However, some screen cleaners say they help protect screens-
Screen Cleaner Gallon
Screen Cleaner by Winsol: (Gallon) Amaze your customers and get that repeat business. Specially developed for cleaning and [B]sealing[/B] vinyl, fiberglass, and aluminum window and door screens. [B]Restores and seals[/B] the screen to a new like appearance. [B]Protects against corrosion and prolongs screen life. [/B]
Has anyone dealt with this stuff?
As for window sealant, these are the types I am talking about-
Glass Guardian Protectant
Glass Guardian by Ettore: Kit includes (16 oz. prep and 16 oz. protectant). The best way to prepare and protect glass from hard water stains and chemical corrosion. Creates an invisible protective coating eliminating the need for costly anti-oxidant procedures and eventual replacement of the glass. 16 ounce bottle will cover approximately 1250 square feet. For best results squeegee off the protectant, do not let air dry because clouding may occur.
Invisible Shield Pint
Invisible Shield by Clean-X: 16 oz squirt bottle. Dual action, cleans and shields in one step. To shield windows against the adhesion and build-up of water insoluble soil and make future cleaning easier. Long lasting liquid coating technology for large glass areas to actively repel rain and sprinkler spray and prevent the adhesion and build-up of hard water stains.