How can I tell if

[OBXWaMi]

How can I tell if a jacket is waterproof or water-resistant?

I found a long forgotten rip-stop nylon jacket in the top of the hall closet. It is a Catalina, half zipp, pull-over that stuffs into its own front pocket for storage/travel.

If it isn't already, can I make it waterproof or resistant?

[Blissful]

I'd go out in rain and see what happens. :)
I know you can buy stuff that restores water repellency - Nikwax makes it

[Jim Adams]

try to blow thru it.

[-SEEKER-]

Whenever I have brought up the "waterproof" question my brother tells me to go stand in the shower. It's actually not a bad idea.

[Cookerhiker]

I would hang the jacket on a tree or somewhere outdoors and spray a garden hose on it.