Tung oil is a favorite of woodworkers, DIYers, and anyone looking for a drying oil that’s both natural and leaves a gorgeous finish. This stuff has been around for centuries and has been used extensively in China as a preservative for wood ships and other exterior wood applications.
The oil derives its name from the seed of the Tung tree, from which the oil is extracted. Pure Tung oil is a natural and environmentally friendly product that can be used without worry on surfaces that will come in contact with food such as cutting boards and countertops.
While Tung oil has many fantastic properties, it’s not the easiest finish to apply. It takes much longer to dry and cure than lacquer or varnish and requires multiple coats to fully penetrate the wood surface.
Let’s take a look at how to apply Tung oil in detail, so you’ll be well prepared for whatever woodworking, carpentry, or restoration project you’re working on.
Tung Oil Types
When you’re working with Tung oil, the first thing to do is determine which type you want to use. There are two different products that are both sold under the name “Tung Oil”, each with its own applications and use cases.
The first type is typically sold as ‘Pure Tung Oil’ or ‘100% Tung Oil’. It’s more expensive than oil with additives, and it’s the only one that’s safe food-safe.
This stuff is exactly what it sounds like, and because it’s free of solvents it takes significantly longer to dry and cure. Think 2 to 3 days to dry between coats and 30+ days to cure completely. Now, this may not be an issue for you if you’re working on a little hobby project, but if you’re coating flooring it can turn into a major pain.
The other type of Tung oil has some type of varnish or solvent added to the mixture in order to increase the drying speed and ease of application. It also lowers the cost of the product significantly.
Manufacturers sometimes aren’t that clear about what type of mixture they’re selling, so make sure to read the label closely to determine what you’re working with.
Applying Tung Oil – Guide
Step 1: Prep the Surface
The first step to successfully applying Tung oil is properly prepping the surface to absorb the oil. Tung oil is a drying oil like linseed oil or walnut oil, which means it needs to absorb deeply into the wood surface to work properly.
Any previous coating or finish must be removed completely before application, which means you’ll need to sand down to the bare wood. If you’re working with wood that’s still coated with varnish or lacquer, then you’ll want to strip it off using trisodium phosphate, mineral spirit, or turpentine.
If you’re restoring an old piece of wood furniture like I am, then you’ll want to sand down the worn grey surface to expose the wood grain hiding beneath.
Start with coarse-grit sandpaper (80 or 100) and remove as much of the surface as necessary to get down to the bare wood. Then switch over to medium grit (120 to 150) to smooth out the surface and remove any scratches.
Keep in mind when you’re working with drying oil that any scratches will be visible after multiple coats. Unlike lacquer, it’s not so much a coating as oil that penetrates and treats the wood.
Step 2: Remove Dust
Next, wipe down the entire surface with a cloth to remove any traces of dust leftover from the sanding process. It’s a good idea to clean the surface with a damp rag or wash it with a hose to completely remove any traces of dust.
Step 3: Prep the Area
Next, lay down a drop cloth or a garbage bag on the surface where you plan to apply the oil. This stuff is pretty sticky, so you want to make sure you don’t get it all over your deck or driveway.
Step 4: Apply the Tung Oil
Next, apply oil using a clean lint-free cloth. You want to soak some oil into the cloth and then rub along the grain of the wood.
The goal here is to strike a balance between soaking the wood and applying too little. You want the oil to go on easily, so there is no need to press hard, while also avoiding the oil pooling on the wood surface.
It’s a good idea to apply oil to the harder-to-reach interior parts first, then the easy-to-access external parts second. That way you’re less likely to get oil all over your arms and clothes.
For this first coat, you may wish to thin pure Tung oil to improve penetration and drying time. Mix your pure oil half and half with a solvent like paint thinner, mineral spirits, or a natural citrus solvent. If your using a tung oil product that’s pre-mixed with a solvent then there is no need to thin the oil.
Step 5: Allow the Coating to Dry
You’ll want to give the oil a generous amount of time to absorb and dry. If you used pure Tung oil in the first step, then we’re talking 3 to 5 days. If you thinned out the oil in the first coating, then it should be dry enough after 12 to 24 hours, depending on how hot the temperature is while drying.
Step 6: Second Coat
After the first coating, you’ll notice the wood has darkened and should have a nice honey color to it. At this point, it’s nowhere near its final appearance, which is why subsequent coatings are necessary to really penetrate the wood and provide a protective coating.
Repeat the process above for the second coating. There is less of a need to thin the oil for subsequent coatings, as the first coat will have penetrated to the maximum depth and the following coatings are intended to build on the durability and appearance of the first coat.
Step 7: Additional Coatings
Two to three coatings will provide a nice-looking finish and a fairly durable protective layer, but many woodworkers will apply 6 or more coatings to really achieve a beautiful finish. It just depends on how much work you want to put into your project.
The process is essentially the same as above, but you may want to sand the surface briefly with fine-grit sandpaper (320+) or steel wood in between coatings to help with adhesion.
And that’s about it! Hopefully, you have a good idea of how to apply Tung oil now.