Most of the time it happens that while looking for an oil finish for woodworking projects, linseed oil, tung oil, or danish oil are what we compare amongst. But, there are only few who understand the differences, usefulness, and benefits of these oils. Danish oil is basically made of polymerized linseed oil or tung oil. However, the composition of this oil varies from one producer to another, as there is no such definite formulation for its production.
But, in this article, we will discuss how tung oil differs from linseed oil, which one is appropriate for which type of wooden project, what are their benefits, additional features, price, etc. Where other synthetic wood finishes like varnish, polyurethane, etc. were mostly used by the woodcrafters, linseed oil and tung oil are seen coming back into effect lately. This is because of the latter being non-toxic and environment friendly in nature.
What is Tung Oil?
Tung oil, also called the China wood oil, is extracted from the nut of the tung tree to use it as a wood finish. This clear cum fast drying oil deeply penetrates into the wood grain to protect and enhance the texture of the wood. Tung oil is the most popularly used and one of the oldest wood finishes, worldwide. The tung trees are found in the Eastern Asia; their seeds are pressed under high pressure to obtain the resultant drying oil.This oil was previously produced and used as a wood finish, in ancient China(for a minimum of 2500 years now) before it got fame across the globe. This oil has turned out to be a staple product among the pro-grade fine craftsmen in the woodworking business. Food safe, non toxic cum eco-friendly characteristics of the oil are some of the points that made this oil the most demanded in the United States and beyond.
It is better not to use the purest or raw form of tung oil to finish furniture. The experienced craftsmen rather use the polymerized tung oil or boiled tung oil. However, sometimes some manufacturers mislabel products as boiled/polymerized tung oil when the reality is something else. So, if you prefer tung oil to any other wood finish, it is better to do some study regarding what is that oil composed of, what kind of tung oil finish you should use, etc.
Compared to linseed oil, tung oil does not cast yellow tint over time. This is a common problem with the application of varnishes like polyurethane, linseed oil, or nitrocellulose lacquer. On the contrary, the tung oil is prone to stains and scratches which is not the case with linseed application. Plus, the former oil finish is costlier than the latter.
Tung oil, because of its resilient properties, is used in a number of applications; be it indoor or outdoor. For example, musical instruments, furniture, wooden floorings, wooden kitchen utensils, and other handmade toys. The added advantage is that you can utilize this finish on metal and concrete surfaces as well.
Though it cures within a couple of hours, it takes about 15 to 30 days to fully cure before the finished product is subjected to use. During this period, you might require to wipe the surface regularly, to remove the excess oil (if any comes out) from the surface.
You can apply about two to four coats maximum for finishing the wood surface. You can even use mineral spirits for thinning, and hence, making the oil application easier.
But before that, you have to thoroughly prepare the wooden surface prior to applying the tung oil. Use a 150-grit sandpaper to sand the surface and use a vacuum followed by a clean cloth to wipe off the dust and oil or grease(if any).
Tung oil finish never fades or turns yellowish over time. But, it often loses the shine, so you might need to recoat the oil after every 6 months, or so.
The Food and Drug Administration (FDA) has added the tung oil to the list of food safe oils. So, it is safe to use for seasoning food surfaces like cutting boards, bowls, etc. which comes in direct contact with the food
What is Linseed Oil?
Linseed oil is also called flaxseed oil and is popularly used wood finish in the wood crafting industry, across the globe. Similar to the hand-rubbed oil finishes, flaxseed oil too gets absorbed deep into the open grains of the wood, thereby protecting the surface from scratches and humidity change. Linseed oil is absolutely eco-friendly plus easy to maintain. This type of finish delivers a smooth/satin finish which brings out the wood grain and its color from underneath.
Though raw linseed oil is its purest form, at times it is impractical to use it as a furniture finish because of its extended dry up time. Raw linseed oil takes about several weeks to cure each coat. That is why, boiled linseed oil is widely used as a wood finish. However, the boiled form is potentially hazardous as it contains some toxic drying compounds. This speeds up the drying process. Polymerized linseed oil is both non-toxic and a pure type of flaxseed wooden finish that has fast drying time.
It is better to use the boiled linseed oil to protect the wood as it deeply penetrates into the wood grain. This form of flaxseed oil is the best for using on outdoor wooden projects. For example, garden furniture, decks, fences, cricket bats, etc. However, the good thing is that BLO has limitless possibilities for indoor applications, starting from tabletops, kitchen cabinets.
The curing time of BLA after each coat may vary from 1 day to 2 days' duration. Depending on the time taken by the oil to dry up, you have to wait till it(the workpiece) is ready for the next coating. There is only one way to check whether or not the oil coating is fully cured; that is to slightly touch the applied surface with your finger. If the surface does not appear tacky to touch, then it means the coating is fully dried and you can proceed with the next layer of coating.
While coating the wood surface, make sure to maintain a time gap of 12 hours to 24 hours after each successive coating. Then take a clean and dry to remove the extra oil (if any excess is coming out of the wood grain). Overall, you can apply about 2 to 3 layers of LO(Linseed Oil) coating as this much is sufficient for ensuring protection.
While considering sanding, use a 120 grit sanding paper to the surface such that it can readily absorb the oil. Then wipe the loose grain particles/debris from the surface with a dry cloth.
Note: Use a 600 to 800 grit sandpaper, to get a satin-smooth surface finish, prior to applying the final oil coat on it.
Application of ordinary wood varnish on the wood surface makes it susceptible to scratches and damage but no discoloration. Linseed oil results in yellowing or discoloration of the wood surface over time. That is why, make sure to look after the product maintenance for once or twice, annually, or whenever it starts fading.
Apart from being used as a popular finishing compound, linseed oil is also used as a food safe additive product. Therefore, if your kitchen utensils involve a wooden cutting board, wooden spoons and spatula, wooden bowl, etc., linseed oil can be used for seasoning them.
Note: Make sure to use the food safe, purest linseed oil for finishing the food surfaces. Boiled linseed oil is strictly prohibited as it contains added chemicals added to it. Use the 100% purest Food Safe Mineral Oil that is odorless and clear.
How Tung Oil Differs From Linseed Oil?
Both the tung oil and linseed oil are non-toxic, food safe as well as eco-friendly in their purest form. The oil extracted from the flaxseed and tung nuts gives the perfect finish to the wood by penetrating deep within and saturating the wood grain.
Here are some key differences between linseed oil and tung oil:
Raw tung oil is used as it is and no metallic dryers or additives are mixed with the oil as the oil naturally dries faster. However, natural mineral spirits like any citrus solvent can be used to thin the oil so that it gets well absorbed by the wood, thereby slightly expediting the drying time.
On the contrary, the purest form of linseed oil takes several weeks to months to fully dry and cure. So, the boiled linseed oil is mostly used for finishing furniture and others. Well, boiling here is not just a process to heat the oil. It is rather a practice of combining metallic drying elements with the oil to speed up the drying time of the oil when applied on the surface. Boiled linseed oil takes only a day to dry.
Tung oil has water resistant property, however linseed oil does not. This makes the former a better fit for wider applications, such as seasoning the food bowls, plates, spoons, cutting, butcher blocks, and other food-related utensils which need regular cleaning.
Note: Tung oil is food-safe but not all forms of linseed oil are food safe.
A pure tung oil delivers honey-color like finish, whereas the linseed oil delivers a golden-brown hue and starts yellowing or discoloration over time. Tung oil prevents molding but is highly susceptible to stains and scratches. Linseed oil finished furniture, on the other hand, are not prone to scratches. The curing time of tung oil is faster than the linseed oil and delivers a hard cum durable flat finish to the surface. Linseed oil gives a lustrous outlook, producing a softer oil finish to the wood surface.
Tung oil and linseed oil contain no Volatile Organic Compounds(VOCs), and are safe to the environment, non hazardous, etc. Tung oil has a couple of benefits over linseed oil. For example, tung oil finished furniture does not fade over time and it is resistant to water. You get an amazing matte finish, plus it is food-safe.
Well, that was all about the differences between tung oil and linseed oil. Now, if you are stuck between the boiled linseed oil and tung oil, then it is better to go with BLO. But, make sure to use it on outdoor projects. You can also use it on indoor projects, except on kitchen utensils as BLA contains harmful chemical additives which are not edible.
On the other hand, if you want to look for the oil finish with water resistance property, then tung oil is the one. Plus, it ensures a hard and durable flat finish compared to linseed oil. At the same time, if you are running on a tight budget, then it is better to opt for the linseed oil.