The key advantages of Spar Urethane are the flexibility and UV resistance (similar to Varnish) which makes it a better choice compared to polyurethane when it comes to exterior uses. Polyurethane may be a better choice for indoor application, thanks to its hard-protective coat. Minwax® Helmsman® Spar Urethane is specially formulated as a protective clear finish for exterior or interior wood exposed to sunlight, water, or temperature changes. Contains UV blockers to reduce the sun's graying and fading effects. Forms a protective barrier against rain and moisture. A ship's spars get exposed to an unusual amount of wind, sun and moisture, so spar varnish has to be more durable than regular varnish to last for any length of time. However, it's a great finish for any woodwork that is exposed to moisture regularly, such as a bar, countertop or shower seat. Spar Urethane is considered to be much easier to apply than polyurethane. It is applied in the same manner like polyurethane; however, it tends to dry faster and doesn't require a lot of layers and application to achieve a shiny finish. Spar urethane cures by oxidation, not by drying, so make sure air circulates. Dry and recoat times are based on 70°F and 50% relative humidity. Allow more time at cooler temperatures. Dries to the touch in 2 hours, to handle in 4-6 hours, and can be recoated in 8 hours. Surface is ready for light use in 24 hours and full use in 3 days.
These days, a spar urethane finish is applied to many different wood features, interior and exterior. Sanding plays an important role in applying urethane. When you want to apply several coats of urethane, you need to sand between each to help the next coat stick. You can also sand out brush strokes and bubbles.
According to Minwax, their Helmsman Spar Urethane may cause mild yellowing over light wood finishes, but their Water Based Helmsman Spar Urethane is supposed to be crystal clear and will not yellow. If used over some other type of light finish, the underlying finish may yellow slightly.
Minwax® Water Based Helmsman® Spar Urethane is a crystal clear, water-based finish that is specially formulated to protect wood against nature's toughest conditions. Special oils allow the finish to expand and contract with the wood as seasons and temperatures change.
Yes, polyurethane provides a protective layer on hardwood (as well as furniture) making it harder for water to penetrate into the wood. But, it is not waterproof; rather, it's water resistant.
According to finishing expert Bob Flexner, all finishes are food-safe once they have cured. Polyurethane varnish does not present any known hazard. However, no finish is food safe until it has fully cured. The rule of thumb for full curing is 30 days at room temperature (65- to 75- degrees F).
oil-based. Both water based and oil based poly offer good protection; the biggest difference is in appearance. It's actually the most durable hardwood floor finish. If you love the natural look of maple, apply a water-based (waterborne) polyurethane.
can i apply the oil based urethane over a water based paint to protect it? Answer: Absolutely. The spar urethane will seal water based paint in just fine.
The key advantages of Spar Urethane are the flexibility and UV resistance (similar to Varnish) which makes it a better choice compared to polyurethane when it comes to exterior uses. Polyurethane may be a better choice for indoor application, thanks to its hard-protective coat.
On the other hand, spar urethane is stronger of the two, and it will coat square feet per gallon, while polyurethane will stick with more problem on the surfaces. Polyurethane finish features a few downsides because it cures, sets and rises more slowly than spar urethane that could dry in a matter of minutes.
Unlike polyurethane, varnish is designed for outdoor projects and is not typically used for indoor surfaces such as a hardwood floor. While polyurethane is water- or oil-based plastic resin, varnish is older and made from resins, oils, and solvents.
Spar urethane is similar to spar marine varnish in that it acts as a protective barrier against water damage and moisture. It also has the ability to flex with the wood, expanding and contracting with changes in temperature.
Top 10 Best Polyurethanes of 2019 – Reviews Interlux Brightside Poly Paint-1 Quart. General Finishes High Performance Semi-Gloss Water-Based Topcoat. Rust-Oleum Varathane Interior Satin Finish-1 Quart. Rust-Oleum Carathane Interior Water-Based Gloss-1/2 Pint. Minwax Fast-Drying Clear Gloss-1 Quart. Miniwax Clear Semi-Gloss Finish-1 Quart.
Spars have a greater oil ratio than an interior varnish or oil base polyurethane. Coating over it with either of those would maintain that softness/flexibility as a base coat. High End spar varnishes ( I wouldn't use these indoors) tend to take much longer to dry and stay much more flexible than spar urethane.