Ever asked yourself if you can put polyurethane over boiled linseed oil? Poly comes in handy if you want to give your wood surfaces a glossy and durable top-coat.

Putting it over boiled linseed oil is an idea you might have thought about. So, let’s answer the big question “can you put polyurethane over boiled linseed oil?”  

Let’s get started!

Can You Put Polyurethane Over Boiled Linseed Oil?

The answer is yes. There’s no real penalty for applying poly over-boiled linseed oil. Follow the steps properly. Polyurethane is a synthetic polymer, and there’re various ways of applying it over your linseed furniture at room temperature. The easiest way to apply poly over linseed oil is to use a spray bottle or brush.


One of the critical things to remember when doing any Polyurethane coating is, you must use tools and materials that will allow the coating to penetrate the surface properly. 

Here is what you will need:

  • Paint Sprayer
  • A Brush
  • Rubber Gloves
  • Fine-bristled Brush
  • Spray Paint Stirrers
  • Vacuum Cleaner
  • Mineral Spirits

If you decide to purchase these materials and tools, you will want to shop around and compare prices. To save money on the coating project, you will need to purchase all necessary materials ahead of time.

Also, read our article on polyurethane vs polycrylic to find out the difference between the two finishes.

How To Apply Polyurethane Over Boiled Linseed Oil (Step-By-Step)

Step 1: Prepare the Surface

First and foremost, you must thoroughly clean the surface you’ll be working on. Make sure the surface is free from dust.

Next, remove all of the materials from the surface. Again, it would help if you kept everything as clean and dry as possible during this process. 

Sand the surface using 320 grit sandpaper towards the direction of the wood grain. Sanding will help eliminate as much of the grooves and burrs that can appear on a smooth surface. 

Removing mold from wood will help your workpiece last longer. Once this is complete, vacuum the surface to remove the particles. 

Step 2: Application

With your workpiece ready, thin the oil-based poly by adding mineral spirit to reduce polyurethane by 10 percent. Don’t thin if you’re using water-based poly. Thinning makes the paint flow smoothly, as well as reduces brush marks. 

Using a fine-bristled brush, apply the first light coat of polyurethane over your boiled linseed oil. Apply a thin and even coat. Once done, wait for it to dry. For water-based poly, please give it up to 6 hours of drying time, while for oil-based, you’ll have to wait for 24 hours.

Step 3: Apply a Subsequent Coat For a Hard Film Finish

Like you applied the first coat, do the same for the second if the first is fully dried. Spread the polyurethane evenly and let it dry completely. Once dry, sand any imperfections the same way you did before you applied the last coat (See our post on Do you sand the final coat of polyurethane). Give it time to cure perfectly.

Two coats are enough to give the workpiece a varnished look if you use oil-based polyurethane. You should never apply more than two coats of oil-based polyurethane, unlike water-based poly, in which you can apply several coats. If you are impressed with the look, finish by polishing the surface with a polished compound.

This means you must know when to apply polyurethane to your surfaces. Another important tip is, only apply oil-based polyurethane over water-based stain and vice versa.

Read also: Can you put polyurethane over varnish?

How Long Does Boiled Linseed Oil Cure?

Raw linseed oil is a drying oil, and despite its short drying time, it will take between 30 to 45 days to cure and can be used as a topcoat. 

Unfortunately, many people confuse drying and curing the paint and tend to use them interchangeably, and they are two distinct processes with significant differences.

However, the actual period will depend on many factors, such as the brand of wood being used, temperature, and how long the oil has been sitting on the wood. 

Different types of woods are likely to take oil a bit longer than others. The number of coats of oil to be applied also makes a difference. 

Applying boiled linseed oil to a surface that has thoroughly dried won’t fully cure it. Drying is achieved when all the solvent has evaporated from the coating. For boiled linseed oil, it is a process that will take up to 24 hours.

Curing is a chemical process where coating fully hardens and toughens. For example, boiled linseed oil cures through oxidation to create a hard film. While you can use your wood furniture after drying, you shouldn’t subject it to hard use. 

What Else Can I Put Over Boiled Linseed Oil Apart From Polyurethane?

So you want to know what you can apply over-Boiled Linseed Oil paint to protect it? 

There’re a few things you can do to help the paint last longer. It is important to remember, oil paints don’t like water. Therefore, it would be best if you never painted directly on the water or let any water stand on the paint as it will cause the paint to flake and chip.

To get the best protection from the paint, you should always use top-quality, natural, organic products to protect the environment and people’s health. Some oils will tell you that they are organic, but they aren’t. So when purchasing an oil painting product, always check the label to make sure it is made with natural products.

Other top coats you can use over boiled linseed paint are:

Should You Sand Between Coats Of Linseed Oil?

Yes, but you shouldn’t sand the final coat. First, I need to mention, this isn’t recommended for decking with grooves since it could cause warping and cracking. But it will work great on oak patio doors, kitchen, and laundry room decks. 

When the surface is no longer tacky to touch, you are good to go. Do a light sanding following the direction of the grain using a 400-600 grit sandpaper, or you can also use a #0000-grade steel wool.

Sanding between coats in each direction gives each coat a nice even look, with the result being the same, a gorgeous sheen that will shine with the sun. 

Before you start sanding between coats of oil, you should consider cleaning the surface with a solution of water and vinegar. This will help to loosen up any dirt or other contaminants that may have been trapped in the oil during manufacturing. 

By following these steps, you will be able to clean your wood surface between each coat of oil to have smooth-looking pieces of wood.

Related read: Do you sand after final coat of polyurethane?

Does Boiled Linseed Oil Darken Wood?

Did you know, Boiled Linseed Oil paint can change the color of any surface? Unlike the liquid paint often available only at art stores, Boiled Linseed Oil can penetrate the wood’s pores, creating a permanent color change in minutes, especially if it is kept in low-light conditions.

When using oil paints, you must consider how oily they are because water must be allowed to dry before painting them. In addition, oil paints do not dry instantly, and they take between seven and twenty-four hours to properly dry.

Water paints take a very long time to dry, and the color gets smudged. But oil paints soak up the color right into the wood. So, in essence, your boiled linseed oil paint job would darken your old wood.

Boiled Linseed Oil stains will lighten over time on certain woods (especially hardwoods) as the wood begins to absorb the oil. But, because of its natural pigment content, oil finishes will darken over time, while the natural color of the wood remains true. 

Most people prefer the darkening effects of a baked-on oil finish over a darker stain, as the lighter-colored stain can fade over time. In addition, most people would prefer the baked-on oil finish over any other type of stain, as the darkening effect is much more aesthetically pleasing than a darker stain that has to settle to the wood after years of use.

Read also: Is linseed oil good for wood?

How Many Coats Of Linseed Oil Should I Apply?

This is a question many people ask themselves when they are in the market for new wood oil paint. The answer to this question can be complex and straightforward simultaneously, depending on your situation. For example, if you have a large piece of wood you want to color, you may want to make more than one coat of oil. 

I recommend you go in two coats. Upon applying the first coat, you can wet sand the surface to prepare it for the subsequent coating. Before sanding, you must be sure that the first coat has dried thoroughly.

Follow a similar process when applying the third and the fourth coat. Three coats will ensure the boiled linseed oil has fully saturated the wood fibers. Again, follow the instructions on the label to prevent causing damages to your furniture.

Read: Methods of removing Linseed oil from wood.

Can You Wipe Water-based Polyurethane Over Boiled Linseed Oil?

Can you use water-based polyurethane to seal your boiled linseed oil furniture? Well, the short answer is yes. But you can never apply them interchangeably.

Water-based polyurethane paints dry quickly, so you should have no problem applying them over Boiled Linseed Oil.

As you may already know, polyurethane is one pretty tough finish that provides many excellent benefits to woodworkers when appropriately used. Unfortunately, it is one of the most difficult, if not impossible, materials to work with on a project due to its instability and tendency to form air bubbles and sink if subjected to heat, humidity, or sunlight.

Can You Put Clear Varnish Over Linseed Oil And Stick?

If you’ve done any research on linseed oil paint, then you know it’s the most versatile oil paint available that seals in moisture. However, many amateur painters aren’t aware of the clear varnish that is available over it. 

This clear varnish works similarly to oil paint and is also widely used by professionals for a topcoat. However, some would argue that it is, even more superior to oil paint. Why is this?

The clear varnish over linseed paint helps prevent the oil fumes from leaking onto your brushes and floor. This means less mess and a more extended painting experience. 

You also don’t have to worry about the paint staining your furniture or fabric if you forget to clean it up. A little bit of water will remove the stains, and you can move on to other projects.

Many people who start painting their homes tend to think they need linseed oil paint supplies to start a project. It’s also untrue that you need to have an ample supply of linseed oil paints. 

You can always mix your oil paint supplies, but you’ll have to do it right away. Remember the more accessible you do the job, the better you’re going to enjoy it.

Related reads:

Can you polyurethane over tung oil?


1. Can I mix wood stain with linseed oil?

Yes, you can blend the two to produce a colored oil cure. It is easy to prepare and apply, and at the same time, they are environmentally friendly.

2. Can you put lacquer over linseed oil?

No, it would be a bad idea to put solvent-based lacquer over a varnish. They aren’t compatible, and you could get a poor finish. It’s fine over the oil, however. Lacquer over boiled linseed oil is a safe bet.

3. Can You Put Polyurethane Over Butcher Block Oil?

Yes, you can apply polyurethane over butcher block oil. The key to success is waiting for the surface to cure entirely and then going ahead with the application.

4. Can You Put Shellac Over Linseed Oil?

Yes, you won’t go wrong if you apply shellac over linseed oil. Shellac will adhere perfectly even when oil hasn’t fully cured.

5. Is Danish Oil The Same As Boiled Linseed Oil?

Blends of Linseed oil, mineral spirits/ mineral oil, varnish, synthetic resins, and or Tung oil make Danish Oil and it is never like Linseed Oil.

Related: Can You Poly Over Danish Oil?

Wrap Up

So, Can You Put Polyurethane Over Boiled Linseed Oil?

Polyurethane paint is common among many woodworkers and is often found in conjunction with epoxy or latex paints. It can add high strength and rigidity, offering much more excellent resistance to cracking and general wear and tear. You won’t go wrong applying it over-boiled linseed oil on your furniture.

The polyurethane coating on boiled linseed oil offers good protection against cracking, breaking, and leakage. 

You are now equipped with the dos and don’ts on the subject question, now check out our article on the guidelines for discarding Linseed oil rags.

3 thoughts on “Can You Put Polyurethane Over Linseed Oil?”

  1. Hi there! I recently put one coat of boiled linseed oil on a new bed frame (made of raw pine wood). It was dry to the touch after 24 hours, and I wanted a darker shade. I went to the store to get a tint to mix with the BLO, but they told me to use Danish oil- and I ended up doing two coats of that on top of the linseed. I’m now concerned that the Danish oil will prevent the coat of linseed oil from curing. Do you recommend sanding everything down and starting at square one again, or should it be fine? Thank you!

  2. Hi Goodell,
    Thanks for the advice and information on boiled linseed oil and polyurethane. I do fretwork and use birch ply wood mainly. I have used boiled linseed oil and now am going to poly the final coating. I have gloss poly . Can I mix the boiled linseed oil say 20% to kill the gloss to a sheen? I am going to try natural wood for some of my fretwork from now on.
    Thanks again


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