Linseed oil (flaxseed oil) is one of the most used finishes in woodworking, known for being an easy-to-apply and natural finish that brings out the grain and color of the wood.
Even though there is a constant battle between natural finishes and modern, synthetic finishes such as polyurethane, many woodworkers swear by linseed oil as the primary choice for their projects.
If you have also recently used linseed oil in one of your projects, you may have noticed that it’s taking a fair amount of dry, which is most likely the reason behind you ending up here.
Without further ado, let’s get down to the question.
How long does linseed oil take to dry, and how can you cause it to dry faster?
Depending on the environment and the number of coats you have applied, raw linseed oil becomes reasonably dry in a week. On the other hand, for linseed oil to completely cure, you will be looking at a timeframe of 2 to 10 weeks.
To accelerate the drying process, place the surface that you have finished with linseed oil in a warm area with low moisture, and ensure that it consistently gets airflow.
If you haven’t applied the linseed oil just yet, you can consider using faster-drying variants such as boiled or polymerized linseed oil.
If you have already bought raw linseed oil, you can mix it with a thinning agent such as turpentine to make it dry quicker.
Moving on, we will discuss what causes linseed oil to dry so slowly, how you can accelerate the drying process, and linseed oil variants such as boiled and polymerized linseed oil that dries quickly compared to raw linseed oil, in greater detail.
How Long Does Linseed Oil Take to Dry?
While linseed oil is a fantastic finish that you can use in most projects, there is no denying that it takes a long time to dry and cure, which can certainly be a dealbreaker at times.
The reason behind linseed oil taking so long to dry compared to synthetic alternatives such as varnish, lacquer, or polyurethane is due to it being a natural substance with no additives, whereas synthetic finishes contain chemicals that allow them to dry quicker.
Even though the exact amount of time depends on conditions such as airflow, temperature, and the number of coats you have applied, raw linseed oil takes at least a week to dry on average and between 2 to 10 weeks to cure completely.
In a room at room temperature that gets an average amount of airflow, we can say that a single coat of linseed oil usually takes at least three days to dry reasonably, with each coat adding roughly another three days.
While you can usually put your project to use after the linseed oil dries to touch, it’s best to refrain from heavy usage until the entire curing process is complete to ensure that the finish doesn’t get damaged.
How to Make Linseed Oil Dry Faster?
It’s only natural to wonder how to make linseed oil dry faster, considering that it takes such a long time to dry compared to most other finishes.
There are two things you can do to accelerate the drying speed of raw linseed oil to a certain level, but even then, it won’t be possible to cause linseed oil to dry as quickly as synthetic alternatives such as polyurethane or lacquer.
The first thing you should do to ensure that your raw linseed oil dries as quickly as possible is to place the surface in an area where it gets consistent airflow.
Linseed oil, just like any other drying oil, dries through the means of oxidation, which is the process of a chemical substance showing change as a result of the addition of oxygen. Since air is the primary source of oxygen, the more the linseed oil comes into contact with oxygen, the quicker it will oxidate, and in return, dry.
The second thing you should do to make raw linseed oil dry quicker is to place the surface in an area where the temperature is high – and the humidity is as low as possible.
Warm air allows linseed oil to dry quicker, whereas a high humidity level has the opposite effect.
If you fulfill all of these conditions, you can expect the drying time of your linseed oil to be lower than the average.
How Does Linseed Oil Cure?
Linseed oil cures by coming into contact with air, which causes it to have a chemical reaction with oxygen.
This phenomenon is called oxidation, a chemical reaction where oxygen found in the air starts combining with a substance, causing it to change.
When linseed oil comes into contact with the oxygen in the air, it undergoes a reaction called polymerization, which causes it to dry and harden.
All drying oils, including tung oil, another substance that is widely used in woodworking, have the same properties that cause them to dry as they come into contact with oxygen.
Boiled Linseed Oil vs. (Raw) Linseed Oil
Boiled linseed oil (also known as BLO) is a substance created by combining raw linseed oil with additives and treating it with hot air.
The main reason behind the creation of boiled linseed oil is to reduce drying times, as the long drying times of raw linseed oil is often the primary reason behind woodworkers choosing not to use it for their projects.
Boiled linseed oil takes two to three days to reasonably dry on average and 30 to 40 days to cure. Compared to raw linseed oil, we can say that boiled linseed oil dries at least twice as fast.
During the manufacturing process of boiled linseed oil, raw linseed oil is treated with hot air that causes it to polymerize to a certain point, but not to a level where it completely dries out.
The treated linseed oil is then combined with chemicals named metallic dryers, which are oil drying agents (such as Japan drier) that allow oils to dry much quicker.
While some woodworkers are reluctant to use boiled linseed oil as it contains chemicals, which goes against linseed oil being a natural finish, the convenience it brings to the table is undeniable.
Polymerized Linseed Oil vs. (Raw) Linseed Oil
Polymerized linseed oil is another variant of linseed oil, produced by heating raw linseed oil to extremely high temperatures (much higher than temperatures used for boiled linseed oil) in a vacuum.
As the vacuum creates an environment with no oxygen, the linseed oil can polymerize without combusting, which drastically decreases its drying time.
Just like boiled linseed oil, polymerized linseed oil is made as an alternative to avoid having to deal with the long drying times of raw linseed oil.
Between boiled and polymerized linseed oil, polymerized linseed oil is considered the better alternative as it can dry (2 to 3 days) and cure (30 to 40 days) as quickly as boiled linseed oil even though it does not contain any chemicals.
As polymerized linseed oil still remains a natural solution, those who want a quick-drying natural finish can use it without worry.
While linseed oil is a fantastic natural finish for your woodworking projects, its long drying times can be considered to be problematic to a point where most woodworkers refrain from using it for their projects.
Even though there are certain things you can do to amplify the drying speed, such as increasing the airflow and the temperature, linseed oil can’t dry as quickly as synthetic alternatives due to its chemical composition.
That being said, those who would like to stick with linseed oil and are looking for quicker-drying solutions can move towards boiled or polymerized linseed oil, which dries and cures roughly twice as quickly compared to raw linseed oil.