The short answer is only use Spar Urethane for outdoor projects where your project will get a lot of direct sunlight.

If this project is an indoor reptile cage then there is no reason to use Spar. Believe it or not it is actually less moisture resistant than regular polyurethanes.

Describe the project to us, including what species it involves and whether it will be indoors or outdoors and we can give more advice.
-----
Currently keeping:

6.10 Gonyosoma oxycephalum (Javan, mixed colors)

0.0.4 Rhynchophis boulengeri

1.1 Philodryas baroni

1.1 Lampropeltis triangulum multistriata

0.0.1 Rhamphiophis rubropunctatus

0.0.2 Morelia viridis (Aru & Merauke locale types)

1.0 Rhodesian Ridgeback

[ Show Entire Thread ]