I'm looking for a spray water-proof sealant that doesn't turn yellow.

I spray deck railings with an insect type sprayer (bought at walmart) loaded with Thompson water sealer...never have yellowing problems....but everything is determined by what you are waterproofing....for instance a painting would be a spray varnish or lacquer....same with indoor wood like wall hangings, an outdoor fence--again Thompson's...for fabric there are other sealers. for plastic/rubber still others....without more info it is impossible to answer.

what are you spraying?

Some products specifically say "non-yellowing" - what is your project so we can help you better?

Rustoleum has a fairly new product available at Lowes called "Never Wet" for most applications and it is also available for spraying on cloth. I spray it on my American Flag so it will last twice as long..

Joanne, Thank you for taking the time to reply. I am going to look into this product.