I gnashed my teeth looking at the polycrylic finish on my restored midcentury dresser – it had yellowed the gorgeous wood I uncovered after endless sanding!
Before you set fire to your workshop in defeat, I’ll explain if using polyurethane can redeem your orange-hued mess into a smooth mirror-like finish worthy of your blood, sweat, and tears.
QUICK ANSWER:
Yes, you can apply polyurethane over polycrylic. This combination provides added durability and maintains the beauty of your wood finish.
What is Polyurethane?
Polyurethane is a clear wood finish composed of polymers and urethanes. When applied to wood, it creates a protective, plastic-like coating that is durable, smooth, and moisture-resistant.
Types of Polyurethane
There are two main types of polyurethane – water-based and oil-based. Each has its advantages and disadvantages that depend on the type of wood used and the project.
Water-based Polyurethane
Water-based polyurethane uses water as the carrier and dries quickly. It’s commonly used by woodworkers. Multiple coats are needed for ideal protection and defense against moisture damage. Advances in formulas reduce the coats required. The proper application provides a hard, durable finish.
Oil-Based Polyurethane
Oil-based polyurethane uses oil as the carrier for the poly solids. It was once considered more durable than water-based, but formulas are now similar. However, oil-based requires safety precautions during use due to toxic VOCs released as it dries and cures.
Proper ventilation is a must. The extended drying time also makes application inconvenient.
What is Polycrylic?
Polycrylic is a water-based, clear finish for interior wood projects. It dries fast, resists scratches and scuffs, and stays crystal clear without yellowing over time. Polycrylic isn’t fully waterproof but provides good water resistance.
It has low VOCs, dries quickly, and is easy to apply and clean up after use. Polycrylic comes in various sheens like gloss, satin, and matte. It’s a good environmentally-friendly option for smaller indoor wood items.
7 Steps to Applying Polyurethane Over Polycrylic
- Prepare the surface – Make sure the polycrylic layer is fully cured and lightly sand it with fine-grit sandpaper to help the polyurethane adhere. Remove any dust.
- Apply thin coats – Brush on a thin, even coat of polyurethane using a high-quality brush. Thin coats will dry faster and be smoother.
- Allow proper drying time – Follow the product directions for drying time between coats. Typical times are 2-4 hours. Test dryness before recoating.
- Sand lightly between coats – Use 220+ grit sandpaper to smooth out any bumps or drips between coats. Clean the surface after sanding.
- Apply 2-3 coats – For best protection, apply at least 2 coats of polyurethane over the polycrylic base. 3 coats are better for a durable finish.
- Clean up properly – Use mineral spirits to thoroughly clean equipment. Properly dispose of rags to prevent fire hazard as they can self-ignite.
- Allow to fully cure – Polyurethane takes about 30 days to fully cure. Avoid heavy use during this time.
Frequently Asked Questioned
1. What are the potential risks of applying polyurethane over polycrylic?
There’s a risk of yellowing over time, especially with light-colored woods. Ensure both layers are fully cured to avoid reactions.
2. How long should I wait after applying polycrylic before adding a polyurethane topcoat?
Wait until the polycrylic layer is fully cured, typically 24 hours, before applying polyurethane.
3. Can I use a spray applicator for both polycrylic and polyurethane finishes?
Yes, both finishes can be sprayed. Ensure a clean nozzle and even application to avoid drips.
4. How do I fix bubbles or streaks that appear when applying polyurethane over polycrylic?
Sand lightly between coats using fine-grit sandpaper to smooth out imperfections. Ensure proper drying time between applications.
5. Is there a specific type of brush recommended for applying polyurethane over polycrylic?
Use a high-quality synthetic brush for water-based finishes and a natural bristle brush for oil-based finishes.
6. How do environmental factors, like humidity and temperature, affect the application of polyurethane over polycrylic?
High humidity can prolong drying times. Apply finishes in a well-ventilated area with a consistent temperature for best results.