Applying spar urethane to outdoor furniture is a great way to protect and beautify your patio sets, tables, chairs, and other pieces. But how many coats of this outdoor sealant should you apply for the best protection? Here is a detailed guide on the ideal number of coats of spar urethane for outdoor wood furniture.
Introduction
Spar urethane is a type of sealant that provides outdoor wood furniture with a protective barrier against weathering and wear. It contains UV inhibitors that prevent sun damage and slow the graying process. Spar urethane also forms a plastic-like coating that repels water and resists mildew and stains.
Applying the right number of coats is crucial for optimal protection. Too few coats leave gaps in coverage, allowing moisture and sunlight to seep through. Too many unnecessary coats can result in pooling, dripping, and tacky spots. Finding the ideal number of spar urethane layers comes down to the preparation process, application method, and your specific furniture pieces.
Preparing the Wood Surface
Proper preparation is key to achieving full coverage and adhesion with fewer coats of spar urethane. Here are some tips:
- Sand the wood lightly with 120-150 grit sandpaper to remove any existing finish and smooth the surface.
- Clean off dust with a dry cloth. Use a vacuum for hard-to-reach areas.
- Apply a wood conditioner or primer if the wood is new or unfinished. This seals the pores for a more even application.
- Allow proper drying time between coats as recommended on the urethane label.
Prepping the wood correctly allows the urethane to fully saturate the surface and builds protection with fewer layers.
Brush On vs. Wiping On
The application method also impacts how many coats are needed. Brushing tends to result in thicker applications. Wiping urethane on in thin layers allows for more control.
Brushing Urethane On:
- Requires 2-3 coats for full coverage
- Allows urethane to be layered on thicker
- Can result in drips if too much is applied
Wiping Urethane On:
- Typically requires 3-5 thin coats
- Allows for a thinner and more even application
- Minimizes brush marks and drips
Wiping on additional thin coats usually produces a smoother, more professional result.
Type of Outdoor Furniture
The ideal coat number depends partially on the specific furniture pieces you are sealing:
- Wood tables: At least 3 brushed-on coats or 4-5 wiped-on coats due to heavy use and wear.
- Wood chairs: 2-3 brushed coats or 3-4 wiped coats since there are fewer flat surfaces.
- Wood benches: 2-3 brushed coats or 3-4 wiped coats provides adequate protection.
- Intricate furniture: Wiping on 4-6 thin coats ensures full coverage of carvings, edges, and crevices.
Vertical and detailed pieces require more coats for comprehensive protection. Additional coats also helps account for application inconsistencies.
Achieving Full Coverage
Here are some signs that indicate when you have achieved full spar urethane coverage:
- The surface has an even gloss across all edges, carvings, and flat planes.
- Brush marks and overlapping application lines have smoothed out.
- The color has stopped deepening with each additional coat.
- A fingertip rubbed across the surface encounters smooth resistance rather than catching on wood pores.
When in doubt, apply an extra coat of urethane to ensure all vulnerable furniture surfaces are properly sealed.
Application Tips for Successful Coverage
Follow these best practices as you apply spar urethane:
- Maintain a wet edge by brushing from one end of the piece to the other without stopping.
- Allow proper drying time between coats as specified on the can.
- Lightly sand between coats using 220-400 grit sandpaper for maximum adhesion.
- Work in a dust-free area to minimize contaminants in the finish.
- Work efficiently and carefully to minimize drips and brush marks.
Proper application technique allows you to achieve full, uniform coverage with fewer coats.
Maintaining the Finish
Once the spar urethane has fully cured, maintain the finish by:
- Keeping the furniture clean and dry to prevent water damage.
- Applying a fresh coat each year as needed to repair scratches and wear.
- Lightly sanding and cleaning the surface before reapplying urethane.
Proper maintenance preserves the protective seal and saves you from having to completely refinish the furniture frequently.
Conclusion
The ideal number of spar urethane coats for outdoor furniture is generally 2-3 brushed-on coats or 3-5 wiped-on thin coats. Adequate preparation, wiping on thin layers, and properly maintaining the finish allows you to achieve comprehensive protection with fewer total coats. Assess the specific needs of each furniture piece and aim for uniform coverage across all surfaces to ensure your patio set stays sealed against outdoor elements for many years. Test small sections first and add additional coats as needed until you are satisfied with the smooth, protective finish.