What is the difference between water based polyurethane and polyurethane?
An oil based polyurethane will continue to amber and darken over time, while water based poly will remain clear for the lifetime of the hardwood floor. This color difference is less noticeable over a stained hardwood floor, but an oil based poly will still exhibit an amber hue that will continue to darken over time.
The water in water based polyurethane tends to “react with the grain” more, so you often need to apply more coats to achieve a smooth, finish.
water based: can last around 10 years when high quality product is applied by professionals, inexpensive lower quality product may last only 5-6 years. Water based is harder which offers greater dent resistance. oil based: generally lasts around 10 years. Oil based is softer which can offer greater scratch resistance.
- Eco Friendly, Healthier & Safer. Perhaps the greatest advantage to the homeowner who goes with a water based product is that there will be virtually no exposure to VOC's – volatile organic compounds. ...
- Faster Dry Time. ...
- Durability. ...
- Clear Finish Maintains Original Color.
How Many Coats of Water-Based Polyurethane are Necessary for a Project? Two coats of finish are suggested for most interior projects. When sealing floors, you should apply three coats. However, do not apply more than two coats in one day.
Water-based polyurethane scratches and dents easily. Oil-based polyurethane coatings provide excellent abrasion and scratch resistance. This makes them a good choice for wood floors or for any application such as cabinets, railings, or countertops where durability is critical.
Polyurethanes do not survive well in direct sunlight or in contact with most organic solvents. Two types are common: polyester based and polyether based, with these backbone structures actually comprising a significant part of a so-called polyurethane resin.
Two coats of finish are suggested for most interior projects. When sealing floors, you should apply three coats. However, do not apply more than two coats in one day. 220 grit sandpaper should be used between coats to remove any air bubbles, but avoid using steel wool.
Water-based polyurethane finish is the best polyurethane for hardwood floors, and many consider it the future of polyurethanes. High-level water-based polyurethane is as durable as oil, easier to apply, and better for you, your family, your pets, and the environment.
It's recommended that you stay out of your home for at least 8 hours after applying a water-based polyurethane finish, though usually, you can walk on it much sooner. For a single-component water-based finish, full cure time is usually 7-14 days.
Should I use water based polyurethane?
A lot of clients think that water based poly is not as durable as an oil based poly, but a newer brand, quality water based poly will last just as long if it is well taken care of! For water based polys, we recommend and use only Bona products, as we feel they are the highest quality water based polys on the market.
Disadvantages of Water-based Paints
Water-based paints take longer to dry in high humidity and lower temperatures. Solvent-based gloss finishes have a higher sheen, but water-based keeps its sheen better throughout its lifetime. The finish is tougher and easier to clean but can become brittle with age.
Water-based polyurethane is unique when it comes to its insignificant, non-irritant odor and fast drying time. However, such great features come at a cost. The price of water-based polyurethane is more expensive in comparison to oil-based poly. Changes in the finish become apparent over time.
Two coats of finish are suggested for most interior projects. When sealing floors, you should apply three coats. However, do not apply more than two coats in one day. 220 grit sandpaper should be used between coats to remove any air bubbles, but avoid using steel wool.
Polyurethane doesn't do that so it needs a mechanical method to stick to the previous coat. If you don't sand, the varnish will flake over time particularly if it is a high wear surface. It will also make the surface much smoother.
Water-based polyurethane can take anywhere from 3 to 21 days to cure. It's touchable after 24 hours. You can put on some furniture after 2 days. And officially cured on the 20th day.
Cons of Oil-Based Polyurethane
Longer dry times. Dents easier due to it softer finish. The odor is unbearable (respirator use is recommended). The floor darkens over time.
COLOR: Oil based poly has an amber hue, whereas water based poly is clear. An oil based polyurethane will continue to amber and darken over time, while water based poly will remain clear for the lifetime of the hardwood floor.
Water based poly dries much faster, and several coats (up to 4) can be applied in one day. Water based poly can be walked on with socks in about 4-6 hours after last coat has been applied, while oil based poly must dry for at least 24 hours before walking on it with socks.
Polyurethanes are durable products, offering many years of service. Lifetimes can vary between 3 and more than 50 years depending on the end use. An average lifetime of 15 years for refrigerators (insulated with polyurethane foam) is just one example.
Why not to use polyurethane?
It's no secret that many paints, varnishes, and clear coats emit VOCs and other harmful compounds after they've been applied to a surface. But of all types of fumes and toxins, avoiding polyurethane fumes may be the most essential due to their potential for harmful side effects.
Polyurethane finishes combined with epoxy primers essentially create a smooth protective barrier on any surface they are applied to. This barrier is virtually impenetrable to atmospheric elements such as moisture, salts, and ultra-violet light, so it keeps weathering elements away from the material it is coating.
Water-based polyurethane requires at least two hours of dry time between coats, and you should only apply two coats in a day. It's important to remember that drying time is affected by temperature and humidity.
Apply 3 to 4 coats of water based polyurethane on wood wait 2 hours in between layers. Apply 4 coats of oil based polyurethane on wood and wait 8 hours in between. Don't apply too many coat and you should be just fine.
How to Apply Polyurethane: When working with any finish. Use natural bristle for oil-based finishes and synthetic filament (polyester, nylon, or a blend of the two) for water-based and water-based oil-modified finishes. Don't use rollers or foam brushes—they create bubbles.
Shellac – Shellac is a varnish made from the resin of the lac bug. It is a softer finish that is often recommended for lighter-colored woods. It is also better for areas with high moisture and frequent wear, as it dries much faster than polyurethane.
Minwax Fast Drying Polyurethane
You can apply it easily over wooden surfaces using a brush, spray, or paint roller. The fast-drying feature makes it easy to use indoors as well as outdoors. Moreover, it also removes most of the stains on unfinished woods and creates a smooth and glossy protective layer.
Polycrylic is not as durable as polyurethane and is meant to be used only on interior surfaces such as cabinets, furniture, and trim. It shouldn't be used in exterior applications or on surfaces that are subject to lots of wear, such as floors, or that are exposed to water.
After this 5-7-day timeframe most of the polyurethane should be dry on the surface, and able to be lived on once again. However, when it comes to the odors produced from the polyurethane finishing in a home this odor can last for months in some cases.
A polyurethane finish is applied to the surface of the wood, but doesn't penetrate it. This finish protects the wood from liquids and scratches. Our urethane finishes are water based, environmentally friendly and create a beautiful and lasting finish.
How do you get the best result from water-based polyurethane?
Applying a Water-Based Polyurethane
Apply a very thin coat of polyurethane with a fine brush, foam pad, or cloth. Work with the grain, and avoid applying too much polyurethane to avoid raising the grain. The initial coat should be dry within a couple of hours, and you can then apply a second coat.
The Best Interior Water-Based Polyurethane Finish Option
ZAR® Interior Water Base Poly Crystal Clear is a clear protective coat recommended for light bare wood or light stain colors. It is environmentally safe and non-yellowing, so you can use it with confidence to protect your interior wood projects.
- BEST OVERALL: General Finishes High-Performance Water-Based Topcoat.
- RUNNER-UP: Minwax Water-Based Oil-Modified Polyurethane.
- BEST BANG FOR THE BUCK: Minwax Polycrylic Protective Clear Finish Topcoat.
Disadvantages of water include flooding, droughts, pollution, waterborne diseases, erosion, corrosion, scarcity, freezing/thawing damage, and its contribution to climate change as a greenhouse gas.
Does Polyurethane Protect Against Water? This finish protects your floors, but polyurethane is not waterproof. It will make your floors water-resistant, though — the coating repels water and helps prevent water absorption.
Eco Friendly, Healthier & Safer
Perhaps the greatest advantage to the homeowner who goes with a water based product is that there will be virtually no exposure to VOC's – volatile organic compounds. These compounds emit noxious fumes which are unsafe for people and pets.
Exterior: Spar Urethane
Good for: Exterior doors, trim, and furniture. Contains UV absorbers that protect the finish and the wood from the sun's rays. Made with a special blend of oils and resins that allows it to flex as the wood surface expands and contracts.
Its advanced water-based, self-leveling formula allows wood projects to be completed with just one coat. It provides a durable finish with exceptional scratch and stain resistance on bare and stained wood.
Polycrylic is not as durable as polyurethane and is meant to be used only on interior surfaces such as cabinets, furniture, and trim. It shouldn't be used in exterior applications or on surfaces that are subject to lots of wear, such as floors, or that are exposed to water.
Dry the first coat for a full 24 hours. If the coat feels tacky or sticky after that, let dry until it feels completely dry. Sand the topcoat with 180 to 220 grit sandpaper. Wipe off any residue after sanding.
What grit sandpaper to use between coats of polyurethane?
To give the subsequent poly layers something to bond to, sand lightly between coats with 320-grit sandpaper wrapped around a hard block. Note: The first coat needs the most sanding to appear smooth; don't worry if it doesn't look as flawless as you'd like at first.
Do I need to sand off old finish completely before applying polyurethane? Generally speaking no, you don't need to completely remove previous finish to apply more of the same finish or a different (compatible) finish1.
Now, while 3 coats is better, customers can also opt to do an additional coat of poly a year or two later. Now how about more than 3 coats. Generally, more than 3 coats of poly doesn't do much good. It's really not needed nor recommended.
Factors Influencing Polyurethane Drying and Curing Times
For a faster-drying wood floor finish, use water-based polyurethane, which takes six hours to dry before being ready for sanding and a second finish. An oil-based Polyurethane is going to take 24 hours before being ready for sanding or touching.
It's all about adhesion. When you recoat after 2 hours you get a chemical bond between layers. If you let it go longer than that, you need to wait 24 hours so it's hard enough to sand and get a mechanical bond.
High Performance Water Based Polyurethane Topcoat. Winner of Fine Woodworking's "Best Overall Choice Award," High Performance Topcoat was voted as the hardest, most durable consumer polyurethane topcoat.
Humidity and Temperature: Polyurethane dries faster in lower humidity and higher temperature. At increased temperatures, the polyurethane will dry faster, at lower temperatures it will take longer.
This is one of the most important factors that you should consider while purchasing polyurethane for your floor. The color of oil-based polyurethane is an amber hue which is a very rich and attractive color and darkens over time. In contrast, water-based polyurethane is clear.
Some homeowners make the mistake of thinking that since water-based finish does not have as toxic of a smell, it is fine to spend the night in the home with it. This is not recommended, because even though the finish may not smell as bad, it still off-gasses toxic fumes while it dries.
The Best Interior Water-Based Polyurethane Finish Option
ZAR® Interior Water Base Poly Crystal Clear is a clear protective coat recommended for light bare wood or light stain colors. It is environmentally safe and non-yellowing, so you can use it with confidence to protect your interior wood projects.
How many coats of water based polyurethane is too many?
Two coats of finish are suggested for most interior projects. When sealing floors, you should apply three coats. However, do not apply more than two coats in one day. 220 grit sandpaper should be used between coats to remove any air bubbles, but avoid using steel wool.
Water-based polyurethane can take anywhere from 3 to 21 days to cure. It's touchable after 24 hours. You can put on some furniture after 2 days. And officially cured on the 20th day.
For water-based polyurethane, the drying and curing time is much shorter. It can take as little as 4 hours for the finish to dry and 8 hours for the fumes to dissipate.
Many will swear by water based products, others will claim solvent based offers more protection and is therefore superior. Our personal opinion is that waterborne polyurethane is better because it is only slightly less durable, has more applications since it doesn't yellow over time, smells less and isn't flammable.
To keep outdoor dust and particles away from the surface, applying polyurethane should take place in a well-ventilated room indoors, with an open window or fan to circulate fresh air.
For oil-based polyurethane, it can take up to 24-48 hours for the finish to dry and up to 72 hours for the fumes to dissipate completely. Therefore, it is recommended that you stay out of your home for at least 72 hours after applying an oil-based polyurethane finish.
Polycrylic is not as durable as polyurethane and is meant to be used only on interior surfaces such as cabinets, furniture, and trim. It shouldn't be used in exterior applications or on surfaces that are subject to lots of wear, such as floors, or that are exposed to water.
There are other structural adhesives available, but epoxy adhesives and acrylic adhesives are the main two alternatives to polyurethane adhesives. They will often far outperform polyurethane adhesives.
Sand Between Coats
Make sure to sand the polyurethane between coats. Sanding removes drips, bubbles and other uneven spots in each coat. Dry the first coat for a full 24 hours. If the coat feels tacky or sticky after that, let dry until it feels completely dry.
