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Oil Vs. Water-Based Polyurethane: What's The Difference?
What Is Polyurethane?
Wood needs some sort of finish as protection against everyday wear and tear and its vulnerability to seasonal expansion and contraction; that's where polyurethane comes in. It's a strong, durable clear coating suitable for a range of wood finishes and is available in different forms and multiple products, including oil and
water-based polyurethane.
Differences In Quality
Oil-based poly dries hard, is durable and strong after applying a few coats, and has a slight amber tone, so sometimes people use it to make the woodwork look slightly aged. On the other hand, water-based poly is thinner, so more coats are needed, has a clear-drying finish and no color is added to the wood with this finish.
Differences In Application
Oil-based poly needs to be diluted, requires a 24-hour wait time before the application of the second coat, is dry to the touch after 48 hours, and its complete curing time is about a month. Water-based poly does not need to be thinned, is ready for a second coat after 8 hours, is dry to touch after 24 hours, and its complete curing time is 20 days.
Differences In Durability
Oil-based polyurethane provides a stronger and more durable finish due to its thickness and the oil base, but it turns yellowish and can break over time. Water-based polyurethane is considered to be a less durable finish but keeps better clarity over time, plus it has no strong odor like oil-based poly does.
Differences In Safety
Polyurethane finish contains known toxins called isocyanates that can harm the health and environment, so it's better to select an eco-friendly product that is much easier to find in water-based poly. Also, oil-based poly has a higher level of VOCs — compounds that can be dangerous to health — making water-based polyurethane a far safer choice.