I have been ordering Zavlar at local HomeHardware, its not in their catalog or online database, but if they contact their central warehouse, they will have it.
I've ordered 2 gallons and used to experiment with, painted the floor drain in my garage (paint always came off the metal and then it got rusty) First coat I used a foam roller, and other coats I liked a brush better. Did 4 coats, 3 sides were 8ftx1ft, 2-1ftx1ft ends, and 2sides on 8ftx1ft top cover Don't think will have any more rust trouble, this stuff sticks bigtime, is flexible no chippping.
Also took piece of scrap 3/4" plywood two brush strokes of zavlar laid piece of 3/16 plexiglass 2" onto plywood and then a couple of brush strokes of zavlar over the 2". When dry I tried to pull it apart, it wouldn't breakfree, very edge would lift but would suck right back down as soon as I removed my shoulder pressure, try a couple of days latter and same thing.
When I build a tank will be putting ledge under an beside window, 3 coats zavlar, drop window in, and then 3 more coats, no silicone.