Tung oil is a popular wood finish because of its consistency. It adds a waterproof layer to the wood, and it’s also food-safe, making it a top choice for dining tables. However, first-time users often wonder: does tung oil darken wood?
In this post, I will discuss how tung oil is used, how it affects wood and added tips for application. Similar to other articles on my site, I also answered questions from my readers at the bottom.
What is tung oil?
Tung oil is extracted from the Vernicia fordii tree nuts. It’s also called China wood oil and will polymerize once exposed to the air for a certain period.
Due to this characteristic, tung oil is used widely used as a finish for various wood materials. This oil dries naturally to enhance the color of your wood piece.
When it comes to durability and water resistance, tung oil is much better than linseed oil or shellac. The fact that it’s natural and food-safe is also a big advantage. This is why tung oil is often used as a finish on wooden tables and chairs.
Take note that tung oil is available in pure form as well as solvent-blended products. Pure tung oil reduces your exposure to volatile organic compounds, but it would be more challenging to apply.
Will tung oil darken wood?
If applied properly, tung oil will have a clear finish. This allows you to show the natural grains and the color of your workpiece. It adds a nice luster on wood, but you should know that not all tung oil products are the same.
Most tung oil finishes won’t darken wood that much. Still, each manufacturer produces tung oils with varying colors. Some will be darker, others are lighter. This will affect the overall result once you applied it to wood.
Still, tung oil won’t darken wood as much as stains do. In some cases, darkening occurs on the wood itself, not because of the tung oil finish.
In my experience, pure tung oil is lighter, while polymerized tung oil would have a darker tinge. Nevertheless, pure tung oil would be lighter than linseed oil and the famous Waterlox Original finish.
Some brands also produce dark tung oil, which is basically pure oil mixed with a resinous hydrocarbon. This is to give it a richer and darker finish once applied on wood.
Overall, it’s all about knowing your finishes. When using a new product, I recommend testing it on a spare wood first. This will let you see how the tung oil will react to curing and buffing.
Best way to apply tung oil
To get the best results in applying tung oil, you should apply it properly. Here are some tips that could help:
- Clean the wood. Before you apply the tung oil, make sure that the wood is bare and has no prior finishes or seals. You can use a fine wood stripper to prep your workpiece.
- Use a lint-free cloth. When applying tung oil, I prefer using a lint-free cotton cloth. Others also use brushes if they want to skip the mess.
- Consider diluting the first coat. Another trick you can do is diluting the first two coats of tung oil with a white spirit. Apply this, and then let it dry for around 30 minutes. After that, you can apply undiluted tung oil, which you need to dry for 24 hours before putting another coat. Some tung oil products can be re-applied every 40 minutes.
- Give it time to cure. Once you’re done applying all the tung oil coating, you should let the wood cure for 30 days. This will give the oil enough time to penetrate the wood grains and cure properly. Nevertheless, you should give it at least 10 days before using the wood surface.
- Use a 0000 steel wool. For a smooth finish, I recommend rubbing the wood surface with 0000 steel wool before every coat. A 600-grit sandpaper will also work, but be gentle to prevent damaging the coating.
- Rub along the grain. Rubbing against the grain would starve the wood of the oil. You should apply the oil along the grain so it would easily penetrate through the wood pores.
- Apply at least 3 full coats. Three full coats of tung oil provide maximum protection for the wood. This will make the wood last longer against various elements, especially humidity.
How long does tung oil last?
Pure tung oil should last a year or two inside the container. However, if you keep opening the lid, it will have a shorter lifespan as air polymerizes the oil.
As much as possible, you’d want to keep the air out of the can. You can try applying a small amount of shielding gas from a MIG welder. Since this gas is heavier, air can’t penetrate through the tiny holes on the oil container’s lid.
When applied to wood, tung oil lasts for years. It doesn’t evaporate and will keep the wood protected when contained in a dry and cool place.
Should you sand between coats of tung oil?
Yes, you can sand between coats of tung oil but make it light and gentle. You want to smooth out the dried oil coating, but you wouldn’t want to cut through the finish. Otherwise, you’ll ruin the coat and may have to redo it.
I suggest using 600-grit or lower sandpaper to keep things lite. You should aim for fine sanding to remove nibs and bumps.
Will tung oil seal wood?
Tung oil is a popular wood finish because it seals and protects the material. It also accentuates the beauty of natural wood. However, tung oil isn’t as hardy as shellac or lacquer. Nevertheless, it still protects well, thanks to its topnotch water-resistant characteristic.
Back in the day, sailors would use tung oil to preserve wood ships. Once the oil has penetrated and cured on the wood, it will create a non-permeable layer that will block water from seeping through. For maximum protection, you must apply at least three coatings on any wood material.
Do I need to thin tung oil?
If the tung oil isn’t exposed too much in the air, you can apply it without thinning. It should penetrate the wood and cure properly. However, if the tung oil has been polymerized due to air exposure, you’ll need to thin it out before application.
To thin tung oil, the most popular option is mineral spirits. If you’re going to use this, you must opt for an odorless formula to reduce your exposure to off-gassing.
If you want an all-natural thinner, look for a citrus solvent instead. You need to mix equal parts of citrus solvent and tung oil for the first coat. For the succeeding coating, you can use three parts of tung oil in one part of thinner.
Just remember that you should never thin tung oil with lacquer thinners or acetone. This will ruin the oil and your wood material.
How do you remove tung oil for wood?
If you’re refurbishing wood that’s been previously treated with tung oil, you first need to remove the old coating. Take note that some tung oil finishes have additives that will make them harder to remove.
I suggest testing a few thinner products on a small spot. Start with turpentine and see if the old tung oil finish will bubble up. Once it does, scrape the spot with fine steel wool. If you get to remove the oil without ruining the wood, you can apply the same method to the material’s entirety.
Can I apply tung oil over a stain?
Yes, it’s possible to stain wood then apply a tung oil after. However, make sure that the stain you used is fully dry. You should also apply a thin first coat, then let it dry before applying succeeding layers.
At least two coatings are advisable if you’re applying tung oil on stained wood. Also, you should let the first coat dry for 24 hours before applying another.
How far does tung oil penetrate wood?
Tung oil penetrates up to 5 mm into the wood. However, this depends on the wood type you’re working on. Fine-grained timbers like maple, cherry, pine, and rosewood may not absorb tung oil deeply. Also, it would take longer for the oil to dry.
Is tung oil flammable?
Pure tung oil isn’t really flammable. However, once it’s mixed with solvent and thinners, it will be prone to accidental combustion.
In woodworking, tung oil with solvents can start unintended fires. This happens when the oil is being applied using a rag. As the rag becomes hotter due to friction, it can combust.
If you’re going to get rid of tung oil-laced rags, make sure that it’s bone-dry first. You can hang it on the edge of the trash can to let it dry before tossing it into the bin.
Does tung oil darken wood? It could if you used a dark tung oil product. Still, most pure versions of this oil won’t cause too much darkening on the wood material. If applied well, it will accentuate the beauty of the wood grain while sealing it against various elements.