I have been using a water-based matt varnish for some wood structures, but it feels "sticky' for up to a week after I brush it on. The bottle is a couple years old.... does this stuff get "too old"?
It's possible that what you have is old, Mikey, but I'd give the Krylon Matte Finish Clear in rattle cans a try. They are cheap (like $4 a can at "Wallyworld) and have worked just fine for me on plastic, wood, and metal.