It is fine to use exterior-grade varnish over interior-grade paint when the finished item will remain indoors, but not if it is intended for use outdoors. The exposure to the elements will degrade the paint layer and cause the varnish to fail, even though the varnish is exterior grade.
How to Use and Clean Wagner Flexio 3000 Paint Sprayer
Frequently Asked Questions
What is the difference between indoor and outdoor varnish?
The only difference between interior and exterior products is the ratio of curing oil to resin. ... Flexibility is needed for exterior projects that are subject to temperature extremes of hot and cold. More resin produces a harder film and is best used indoors.
What is the best varnish for indoor wood?
Polyurethane varnishes are the preferred option for wood floors. The harder surface they create tends to provide great overall protection from the effects of heavy use. On the downside, they are not UV-resistant—for this reason, polyurethane is better for indoor use.