As a woodworker, you will need to be acquainted with different types of wood finishes. Two popular wood finishes that you can get are boiled linseed oil and tung oil. Each of these oils has its advantages and disadvantages. Moreover, you need to adopt different procedures to use each oil.
Linseed Oil and Tung Oil are two of the most popular wood finishes you can get. Linseed oil made from flax seeds and often “Boiled” Linseed Oil (that has additives for faster drying times) is often used for interior wood. Tung Oil is made from the seed of the Tung tree. Tung oil can take weeks to totally cure.
We also touch upon how to use each type of oil, and where each one is best suited.
Linseed Oil vs. Tung Oil
Boiled Linseed Oil (BLO)
What Is Boiled Linseed Oil?
We extract linseed oil from flax seeds of the flax plant; hence, we also call it flaxseed oil or flax oil. It allows us to impart a lustrous finish to the wood. However, you need to know how to do it properly.
Why do we boil linseed oil? Well, the explanation is quite simple. In its natural state, linseed oil has a high level of viscosity. Also, it takes a very long time to dry.
Due to these reasons, it is “boiled“, to make it more usable but that term creates a lot of confusion – it has nothing to do with “boiling” as you would for heating water for cooking – it refers to the process of adding metallic solvents to the linseed oil for faster drying times
Linseed Oil Uses
Because boiled linseed oil gets absorbed into the wood grain, it can protect the wood from the elements. This makes it a very good option to use on wood outdoors. The outdoor woodwork that we can apply BLO to is decks, garden furniture, fences, and any structures that get exposed to the elements.
However, the indoor uses of BLO are limitless. From hammer handles and cricket bats to tabletops and kitchen cabinets. We can use BLO for finishing the wood of all such wooden items.
Linseed Oil Curing Time
The curing time of boiled linseed oil can vary from 24 to 48 hours. Based on the time it takes for linseed oil to dry, you need to wait between applying successive coats. The only way to check whether the oil has cured sufficiently is to check physically by touching with a finger. Once the fine layer of oil ceases to be tacky to the touch, you know it is dried.
Linseed Oil Number Of Coats/Sanding
Use 120 grit sanding paper to make the surface of the wood ready to absorb the oil properly. Then wipe the surface with a dry cloth to get rid of the loose debris.
You will probably find two to three coats sufficient to ensure adequate protection. You should also leave a 12-hour to 24-hour gap between each coat so that each coat dries properly.
To ensure a satin-smooth finish, use 600 grit to 800-grit sandpaper before applying the final coat. You can also use 000000 fine steel wool.
Linseed Oil Water-Resistance
Linseed oil doesn’t offer complete water resistance. In fact, wood treated with boiled linseed oil is known to develop mildew in certain climatic conditions. However, linseed oil, being an oil, offers some degree of water resistance.
Linseed Oil Price
There is a huge price variation between different grades of linseed oil. However, for general purposes, you can usually get a liter of boiled linseed oil for less than the same amount of Tung Oil.
Linseed Oil Yellowing/Discoloration Over Time
Unlike regular wood varnish that may be prone to scratching but not discoloration, linseed oil discolors over time. Hence, you will probably need to do maintenance once or twice a year, or whenever you notice discoloration.
Linseed Oil Food Safety
Linseed oil is one of the few wood finishes considered to be food safe. The FDA has actually approved linseed oil as a food additive. Hence, if you want to use it to season a cutting board or a wooden bowl, you can do so. If you are using linseed oil for finishing food surfaces, make sure you are using “pure” food-safe, not a boiled linseed oil that has chemicals added to it, or use a pure mineral oil 100% Pure USP Food Grade Mineral Oil that is clear and odorless. They are often sold as cutting board oil.
What Is Tung Oil?
We call tung oil (also called Chinese wood oil) a drying oil. It comes from the seed of the tung tree in China and some other countries in Asia. Wood with a tung oil finish imparts durability to it and this oil presents an environmentally friendly option. It is also food safe.
Why do people prefer tung oil as a finish for their projects? The reasons are many. It dries fast and provides sufficient waterproofing, resistant to mold, darkening, or going rancid. The resultant matte finish is appealing.
Types Of Tung Oil
- Pure Tung Oil: It is tung oil in its purest form devoid of additives like petroleum distillates, minerals, or thinners.
- Polymerized Tung Oil: This is a variation of tung oil heated to become more durable.
- Dark Tung Oil: This form is the same as pure tung oil, but with a pigmented resin added for color.
Tung Oil Uses (Indoor vs Outdoor Uses)
Due to its resilient properties, we use tung oil in several applications such as in furniture, musical instruments, wooden floors, and handmade toys. It even finds a use for finishing concrete and metal.
Tung Oil Curing Time
Although tung oil dries in a few hours, the curing time can be from 15 to 30 days. During this time you may have to wipe off any excess oil that may seep to the surface.
Tung Oil Number Of Coats/Sanding
You need to prepare the surface thoroughly before you apply a finish of tung oil. Ensure that the surface is free from dust, oil, or grease. Use 150 grit sandpaper, and wipe or vacuum the surface to clean it.
You will need to add two to four coats of tung oil to finish your surfaces. You may find that you can apply the oil easier by thinning it with mineral spirits.
Tung Oil Water-Resistance
Tung oil naturally closes in and seals the surface of the wood, resulting in adequate waterproofing. It performs pretty well in marine conditions, hence, we also use it on boats for water resistance.
Tung Oil Price
The price can vary with different brands and grades of tung oil and you can save money buying larger formats if you go through a lot of projects (gallon, 5-gallon), but generally, it often costs about 20-25% more expensive than BLO.
Tung Oil Yellowing/Discoloration Over Time
The advantage of using tung oil is that it will not yellow or discolor over time. However, it may lose its luster, so you would do well to reapply oil every six months or so.
Tung Oil Food Safety
The FDA includes tung oil among the oils that are food safe. Hence, you can use it on wood that will come into contact with food like fruit bowls and cutting boards.
So, which oil will you use for finishing your woodworking product? The answer to this question purely depends on the different uses of these two oils. We have gone into great detail to outline the different aspects of each oil in this discussion of boiled linseed oil (BLO) vs tung oil.
Hence, you need to decide where to use either of these two oils. Knowing more about these oils and how to use them is a critical part of becoming a competent woodworker. Now, you should be more aware of these two oils. Hence, you can impart some great finishes for your woodworking projects. If you’re still trying to decide what kind of oil to finish your project with, also check out his comparison of Tung oil vs. Danish oil vs. Teak oil.
Featured Image by Schriever AirForce Base