Can You Use Oil Based Polyurethane Over Water Based Stain

Ever wondered if you can mix oil-based polyurethane with water-based stain? You’re in the right place!

I am going to dive into the nitty-gritty of combining these two finishes. Why does this matter? Because getting it right can transform your woodworking project from ‘meh’ to ‘wow’! Stick around, and I’ll show you how to master this technique for a stunning, durable finish.

The Types of Polyurethane

There are two main types of polyurethane: polyester and polyether.

• Polyester polyurethane is made from a combination of polyester and isocyanate. It is a hard, durable material that is often used in applications where strength and resistance to chemicals are important. For example, polyester polyurethane is used in the manufacture of gears, bearings, and other machine parts. It is also used in the production of paints, varnishes, and other coatings.
• Polyether polyurethane is made from a combination of polyether and isocyanate. It is a softer, more flexible material than polyester polyurethane. It is often used in applications where comfort and cushioning are important. For example, polyether polyurethane is used in the manufacture of foam mattresses, seat cushions, and other soft goods. It is also used in the production of adhesives and sealants.

In addition to these two main types, there are also a number of other types of polyurethane, including:

• Solvent-based polyurethane is a type of polyurethane that is dissolved in a solvent. It is a fast-drying, high-performance material that is often used in industrial applications. For example, solvent-based polyurethane is used in the manufacture of paints, varnishes, and other coatings.
• Water-based polyurethane is a type of polyurethane that is dissolved in water. It is a low-odor, low-VOC material that is often used in consumer applications. For example, water-based polyurethane is used in the manufacture of wood finishes, floor finishes, and other coatings.
• UV-curable polyurethane is a type of polyurethane that is cured by ultraviolet light. It is a fast-drying, high-performance material that is often used in outdoor applications. For example, UV-curable polyurethane is used in the manufacture of marine coatings, architectural coatings, and other coatings.

Water-based Poly

Water-based polyurethane is a type of polyurethane finish that is applied with water rather than with a solvent. This makes it a safer and more environmentally friendly option than traditional oil-based polyurethanes. Water-based polyurethanes are also easier to clean up, and they dry more quickly.

Water-based polyurethanes are available in a variety of finishes, including gloss, satin, semi-gloss, and matte. They can be used on a variety of surfaces, including wood, metal, plastic, and concrete.

Oil-based Poly

Oil-based polyurethane is a type of polyurethane finish that is made with a solvent, such as mineral spirits or turpentine. This makes it a more durable and water-resistant finish than water-based polyurethanes. Oil-based polyurethanes also have a richer, more amber color than water-based polyurethanes.

Like water-based poly, oil-based polyurethanes are available in a variety of finishes, including gloss, satin, semi-gloss, and matte. They can be used on a variety of surfaces, including wood, metal, plastic, and concrete.

The disadvantage of oil-based polyurethane, though, is its chemical composition and odor.  The oil-based finish is much higher in VOCs than water-based finishes and, as such, is not available in all parts of the country. While it is easy to clean up water-based polys using water, oil-based polys must be cleaned up after with mineral spirits.

VOCs (volatile organic compounds) are emitted as a gas during the drying and curing of the poly, and they are harmful to humans and animals.

A respirator should be worn when using an oil-based poly, and the room should be very well-ventilated with plenty of air circulation – windows and doors open, fans whirring.

Water-based Stain and Oil-based Stain

Water-based and oil-based wood stains are two of the most common types of wood stains available. They both have their own advantages and disadvantages, so it is important to choose the right type of stain for your project.

Water-based stains are made with water as a solvent, while oil-based stains are made with oil as a solvent. Water-based stains are generally considered to be easier to apply than oil-based stains, and they have a lower odor. They also dry more quickly and are less likely to yellow over time.

However, water-based stains are not as durable as oil-based stains, and they may not provide as much protection from the elements.  Advancements in water-based stains may be bringing them closer in durability to oil-based stains, though, too.  Water-based stain will tend to raise the wood grain more than oil-based, so a bit more sanding will be required to smooth out the wood grain for a smooth finish.

Oil-based stains are more durable than water-based stains, and they provide better protection from the elements. They also have a richer color and can be used to create a more dramatic finish. However, oil-based stains are more difficult to apply than water-based stains, and they have a strong odor. They also dry more slowly and can yellow over time.

Which type of stain is right for you?

The best type of stain for you will depend on the specific project you are working on. If you are looking for a stain that is easy to apply and has a low odor, then a water-based stain may be a good choice. If you are looking for a stain that is durable and provides good protection from the elements, then an oil-based stain may be a better option.

Here is a table summarizing the advantages and disadvantages of water-based and oil-based wood stains:

Feature	Water-based Stains	Oil-based Stains
Ease of application	Easier	More difficult
Odor	Lower	Stronger
Drying time	Quicker	Slower
Yellowing over time	More likely	Less likely
Durability	Less durable	More durable
Protection from the elements	Less protection	Better protection
Richer color	Less rich color	Richer color
Dramatic finish	Less dramatic finish	More dramatic finish

Ultimately, the best way to decide which type of stain is right for you is to experiment with both types and see which one you prefer.

Can You Mix An Oil-Based Finish Over A Water-Based Stain?

We’ve already established that oil and water generally, do not blend well absent an emulsifier.  But what about oil-based finishes and water-based stains?  Can you blend them?  Do you need an emulsifier?

Oil-based polyurethane can be used over a water-based stain, yes. However, there are a few things to keep in mind.

It is essential the water-based stain has completely dried first.  Stains come with application instructions that include drying time, and we suggest you add a bit to the recommended drying time before applying an oil-based polyurethane. If the stain has not dried fully, the polyurethane may not adhere properly.

You also want to lightly sand the wood’s surface before applying the oil-based polyurethane. This will create a texture to the wood’s surface that will help the polyurethane adhere better.

Finally, be aware that the oil-based polyurethane may darken the color of the water-based stain. If you are concerned about this, you can apply a coat of clear water-based polyurethane before applying the oil-based polyurethane. This will help to seal in the color of the water-based stain.

What To Do When Applying An Oil-based Polyurethane Over A Water-Based Stain

We suggest these six steps to apply oil-based polyurethane over water-based stain:

1. Let the water-based stain dry completely.  Go a bit longer, just to be sure, too. 
2. Sand the surface of the wood lightly with 220-grit sandpaper.  You want to create some texture for the poly to adhere to when applied. This will also smooth out the wood grain, as staining can raise it when applied – after all, water-based stain has water in it, and water will bring the wood grain out. You want a smooth wood surface on your project.  We also recommend wearing a dust mask during this part.
3. Wipe away any dust from the sanding with a tack cloth or even a damp cloth.  You might want to consider vacuuming the wood’s surface in addition to using a tack cloth just to be sure there is no nook or cranny where dust has accumulated.
4. Apply a coat of oil-based polyurethane in thin, even coats.  You should mix the poly well, but by stirring rather than by shaking the can.  Shaking will create bubbles, and bubbles will mean you will need more sanding between coats.  A foam brush will reduce the chances of bubbles forming during application, too, and help you avoid brush marks, too.  
5. Let each coat dry completely before applying the next coat.  Remember that oil-based poly takes much longer to dry than water-based polyurethane, and this will slow your project completion. Follow product recommendations on the can for that drying time.
6. Apply additional coats of oil-based polyurethane for best results, 2-3 coats, at least.

Here are some general tips for applying an oil-based polyurethane:

• Use a high-quality brush or roller to apply the polyurethane.
• Apply the polyurethane in thin, even coats.
• Let each coat dry completely before applying the next coat.
• Sand between coats with 220-grit sandpaper to smooth out the finish.
• Apply 2-3 coats of polyurethane for best results.

With proper preparation and application, oil-based polyurethane can provide a beautiful, durable finish to your wood projects.

Are There Polyurethane/Stain Products?

Yes, there are polyurethane and stain mixes available. These products combine the stain and polyurethane into one step, which can save time and effort. However, it is important to note that these products may not provide the same level of color and protection as using separate stain and polyurethane products.

Here are some of the advantages and disadvantages of using polyurethane and stain mixes:

Advantages

• Save time and effort
• Easy to use
• Provides a water-resistant finish

Disadvantages

• May not provide the same level of color and protection as separate stain and polyurethane products
• Can be more expensive than separate products
• May not be available in all colors

Ultimately, the best way to decide whether to use a polyurethane and stain mix is to consider your individual needs and preferences. If you are looking for a quick and easy way to stain and protect your wood, then a polyurethane and stain mix may be a good option.

However, if you are looking for the best possible color and protection, then you may want to consider using separate stain and polyurethane products.

We will admit we’ve never used a stain with polyurethane product before, and this information was sourced from product descriptions (MinWax PolyShades line of products) and bulletin boards.  If we do ever try one, we’ll write a separate piece to share our experience.