Need good outdoor clear

Hi Charlee, Here's a short video that may help! https://www.youtube.com/watch?v=HFG4iyZkS5k

Good luck!

Marine varnish would probably be your best choice

Yes , marine varnish would be your best bet.

Make sure it says "non yellowing" - a marine varnish should work well.

I made a painted sign for outdoors and after the painting was completed I did one coat of clear Marine Varnish. It did make my white paint just a little bit yellowed looking, but should make my sign withstand all the weather here in South Dakota.

We replaced the rotten steps out our back door and used a light stain and polyurethane for outdoors and it has been two years without a problem. We also put stained plywood under all of our large fish tanks(smallest is 75 gallons), and we put the same polyurethane on them to protect the plywood from water spills. This protects the flooring underneath from damage with water spills. Three of them are saltwater tanks over carpet.