What is Linseed Oil? (Properties, Uses, Types, Advantages & Disadvantages)

Linseed oil can penetrate deep into the wood grain, protecting it from damage caused by humidity, heat, and scratches. Linseed oil is easy to maintain and eco-friendly. Moreover, it creates a satin finish that brings out the natural tone and color of the wood.

If you do not provide wood with a good finish, it might dry out and look dull, leading to its deterioration upon exposure to heat and moisture. As such, it is necessary to finish wood to protect its surface from these natural elements. One of the popular wood finishes you can use is linseed oil. It is also referred to as flaxseed oil and is a hand-rubbed oil finish. 

How Is Linseed Oil Produced?

The flax plant with the scientific name Linum usitatissimum is the source of linseed oil. It has been cultivated for thousands of years for use as textile, oil, and seeds. The fibers of this plant get processed into canvas, paper, textiles, and oil, and you will often find the end products in tablecloths, clothing, and bed sheets. You can also use its seeds as supplemental food. Besides, you can process its seed to produce linseed oil.  

Properties and Characteristics of Linseed Oil

If you intend to use linseed oil as a finishing for wood, it will be best to know its properties and characteristics to determine if it is the best finish for your wood projects. Below are the succinct properties of linseed oil:

Linseed Oil Dries Uniformly

One sterling characteristic of linseed oil is it dries uniformly. It also dries slowly. Because of these properties, linseed oil is usually utilized as a drying agent in many finishing products and paints. 

It Renders a Glowing Effect on the Wood

The main constituents of linseed oil include triglycerides and fatty acids. It has saturated fat locked in waxes or triacylglycerols, which makes it glow.

It Makes Wood Water-resistant

Linseed oil saturates the wood pores and covers the wood surface with a thin film that keeps moisture and water out of the wood surface.

It Exhibits a Binding Property

The linseed oil works like a binding agent when combining various ingredients. It offers a smooth and rich emulsion when ingredients are mixed. 

Advantages and Disadvantages of Using Linseed Oil

Aside from knowing the properties of linseed oil, it will also help if you are familiar with the advantages and disadvantages of its use. Below are the succinct advantages and disadvantages of the use of linseed oil:

Pros:

• Let the color and texture of the wood grain come out.
• Allows easy sanding of dents and scratches.
• Eco-friendly 
• Offers wear and water resistance.
• It is elastic.
• Not that expensive
• Affords ease of maintenance
• Doesn’t necessitate a special technique to dry. Its boiled version also dries quicker than the unboiled version. Besides, it can dry within a day or less.
• Penetrates well into the wood grain 
• Doesn’t alter the natural tone and color of wood
• Usable alongside wax and other finishes.

Cons:

• Necessitates reapplication occasionally
• Might be vulnerable to water rings
• Its commercial version might contain harmful additives
• Pure or raw linseed oil might take longer to dry
• Might take longer to dry if the weather is cold. It might also not cure properly if the weather is cold. This inability to dry appropriately might lead to a sticky wood surface. You can prevent this by applying a thin linseed oil coat to make it dry well. You can also thin the oil using a bit of turpentine. Let each coat completely dry. 
• Not UV light resistant. So, it might get damaged over time if exposed to UV light.
• Might show mildew growth
• More susceptible to damage or scratches compared to varnish or lacquer
• Tends to look yellowish over time
• It is susceptible to the effects of the vicissitudes of the weather and might cause bleeding of the wood.
• Might make the wood susceptible to staining

Applications and Uses of Linseed Oil

Aside from knowing the pros and cons of the use of linseed oil in wood, it will also help if you familiarize yourself with the following different applications of linseed oil in woodworking. This way, you can determine whether linseed oil is best for finishing your wood projects:

• You can use linseed oil to finish materials like outside and wooden deck floors. 
• You can use the linseed oil to darken the wood’s color to enhance the wood grains. Besides, you can use it as a primer before you paint the wood surface.
• Linseed oil protects the wood by penetrating deep into the wood grains. You can use it to prevent decay by enhancing the wood’s resistance to moisture and water.
• If the wood surface got painted and varnished previously, you can remove the previous coating and finish it with linseed oil. 
• Linseed oil might require refinishing. So, you can go for another type of finish if you desire a longer-lasting finish.
• You can apply two to three coats of linseed oil and let each coat cure.
• You can use linseed oil in places that don’t encourage mildew growth. It is better to refrain from using linseed oil in places conducive to mildew growth.

Different Types of Linseed Oil

Linseed oil has three basic types: raw linseed oil, boiled linseed oil, and polymerized linseed oil. As someone who wants to use linseed oil, it will be best to know what these three basic types of linseed oil are before you buy linseed oil:

1) Raw Linseed Oil

Raw linseed oil constitutes the purest form of linseed oil. This linseed oil is unadulterated and not tinged with any additives. However, it is often impractical to use them as a finish for furniture because of their long drying time. The drying time of raw linseed oil takes around several weeks for every coat of this oil. 

The raw linseed oil, however, is suitable as a nutritional supplement. You can also use it as a leather conditioner likewise. You can also use it as a finish for wood if you apply it in thin coats and allow each coat to dry for a longer time. 

If you apply it thickly, it might fail to dry and take you more weeks to finish the wood. For this reason, many woodworkers would instead use the polymerized version of linseed oil or other alternative oils for quick-drying. 

2) Polymerized Linseed Oil

You can make polymerized linseed oil by heating pure linseed oil at 300°C without oxygen for several days. This way, polymerization will happen, and the viscosity of the linseed oil increases while the drying time shortens. Polymerized linseed oil, as well as raw linseed oil, has no VOCs or volatile organic compounds. 

3) Boiled Linseed Oil

Boiled linseed oil is often referred to as BLO. You may think that it is linseed oil that is boiled. Yet, this version of linseed oil doesn’t undergo boiling. Yet, it contains drying agents like heavy metals and petroleum-based substances, making it a better option for finishing wood than raw linseed oil. 

Usually, naphtha, di-propylene glycol monomethyl, and mineral spirits get added to the oil. Among the metals added to linseed oil, the most common are manganese and cobalt. Due to its drying agent contents, this version of linseed oil is not fit for finishing wood items used for food handling because it is not food grade.

Frequently Asked Questions on Linseed Oil Finish

Aside from learning the different types of linseed oil that you can use, it will also help if you are cognizant of the following FAQs about linseed oil, for they might also be the questions you have in mind:

How Should You Use Linseed Oil?

Pure linseed oil will never be problematic when you handle it, for it is food safe and eco-friendly. However, the commercially available linseed oil products often contain combustible solvents for thinning this oil, making this oil highly combustible and flammable. Since you will use a rag to apply this oil, it will be best to dispose of the rags you use with enough care. 

Before disposing of the used rags, let the rags dry thoroughly in any non-flammable place or medium. Besides, before you dump the rags into the garbage bin, it will be best to soak them in water to lessen their combustibility. 

Used rags with solvents might generate enough heat due to exothermic reactions with oxygen. Such a reaction can make the rag hotter and might start to burn, causing an accidental fire that could cause damage to properties.   

How Long Would Linseed Oil Stay in the Wood?

Linseed oil is only a temporary protection for your wood, requiring you to refinish the wood when the linseed oil diminishes. 

However, the frequency of refinishing the wood will depend on the linseed oil type you’ve used on your wood and the location of the wood you have finished with linseed oil. For example, if the wood takes a heavy beating, you need to refinish the wood more often. 

You can refinish the wood at least once yearly if you use linseed oil. However, if the wood often takes a beating, you can refinish it every six months. Inspect the wood for any degradation of its color. Besides, if it exhibits color change, you can reapply linseed oil coats to bring back its natural tone and hue. Dryness and discoloration are indicators of the need to refinish the wood with linseed oil.

Conclusion

Linseed oil is a crucial and safe component of coatings, commercial paints, and sealants. Nevertheless, it can ignite if it comes in contact with potent oxidizers. It is flammable only if it gets oxygenated, and it will ignite when reaching its burning point. 

As an oil finish, its use comes with many pros and cons. So, if you would ever like to use this finish, it will help you be cognizant of the abovementioned pros and cons to decide wisely whether this finish is best for your project.