Typically, woodworking pieces only receive one finish, occasionally several applications of natural oil like boiled linseed oil, lacquer, shellac, or polyurethane. Generally speaking, the first layer has the same type of finish as the last coat. In some cases, switching finishes from one layer to the next may be desirable.
For instance, some people argue that a base coat of Tung Oil will significantly enhance the grain, but they also want to have a top coat of varnish to provide further protection. Others may apply an oil-based stain but question if they can follow it up with water-based polyurethane, or perhaps you are repairing an older piece and are unsure whether you need to remove all the previous finishes before applying the new one.
Understanding which finishes work well together can mean the difference between success in accomplishing the task and failure. This guide, which focuses on applying Tru Oil over Tung Oil finish, will help you comprehend the how and why of changing finishes between layers.
On the topic of applying Tru Oil over a Tung Oil coat, these are the points that will be discussed:
- Tru Oil and Tung Oil description
- Can you apply Tru Oil over Tung Oil
- Reasons for applying Tru Oil over Tung Oil
- Surface preparation for Tru Oil finish
- Applying Tru Oil to the surface
- Drying and curing
What is Tru Oil and Tung Oil?
Wood surfaces can be made from organic materials such as oak, walnut, maple, and beech wood. The selection of oil finish can determine whether one has a surface with a glossy shine or a satin appearance.
– Tru Oil
This kind of finish is frequently utilized because of its low cost. It does not require much drying time and is simple to apply with a clean, soft cloth. Because of this, it is a fantastic option if someone wants to work faster and apply several coats in one day.
It is not quite pure organic oil per se because the formula itself incorporates several other substances, including mineral spirits, oil varnish, and linseed oil. It resembles a varnish more than anything else. It makes it a wonderful alternative for bringing out a wood’s elegance as well as for protection since successive coats can stack up and attain a relative degree of hardness.
Tru Oil is suitable for use on any natural wood, but it is frequently applied in several applications to a surface that has not been finished. If someone applies enough coats, they will achieve a smooth finish that does not feel sticky in a humid climate.
– Tung Oil
Because of the way it is infused into the wood, Tung Oil typically leaves a surface that seems more natural than Tru Oil. It is especially true when someone runs their hands up and down the surface; they can truly feel the wood’s grain on their fingertips. Some people prefer this to the smoother feel of a surface with Tru Oil or another kind of lacquer.
Tung Oil might not be the best option if someone is searching for a finish option that requires little upkeep. It is because it will occasionally require reapplication as it is absorbed into the wood.
Can Tru Oil Be Applied Over Tung Oil?
The most popular natural penetrating oil is Tung Oil, and it is called a penetrating finish because it is designed to seep into the wood fibers rather than being significantly built up to form a protective layer on top of the wood surface. Tung Oil tends to take several weeks or even months to fully cure. Do not confuse drying with curing.
The surface may feel dry when you touch it because the Tung Oil has soaked deeply into the wood fibers or even because the solvent thinners used have evaporated. Curing is a chemical process in which oxygen reacts with the oil finish on a molecular level, causing it to harden.
Only once the finish has cured completely may you apply a different sort of finish, such as Tru Oil, on top. Since oil is compatible with oil, even if the oils are from various sources, you can apply an oil-based finish over a penetrating oil finish.
Why Is Tru Oil Used Over Tung Oil?
Tru Oil finish offers a higher level of protection due to the several layers that cover the surface on application. The level of protection provided by Tung Oil is not very strong. It is unquestionably far preferable to having nothing at all, but longevity over time is not among its strongest qualities.
Another thing to keep in mind is that Tung Oil finishes are prone to getting dirty since dirt still penetrates through the wood trim. Because there is not much you can do to remove dirt once it is embedded in the wood other than to sand out as much as you can and start over, it is important to maintain it clean. That is why Tru Oil can be used to offer extra protection on top.
You ensure the Tung Oil you are using is at least reasonably pure. Many items on the market make this promise, but in reality, they are frequently just “Tung Oil finishes” with a low amount of natural Tung Oil. Because the results may not be clear-cut, there may be a wide range of beliefs regarding how excellent a finish Tung Oil provides.
Tung Oil finishes take a very long time to cure and dry. The fact that there are so many goods on the market marketed as Tung Oil but are actually created from synthetic materials is largely due to the lengthy drying process. Usually, chemicals are added to them to hasten the due to the lengthy drying and curing process of Tung Oil.
The use of Tung Oil finish is a tedious and time-consuming process, particularly when someone has to wait for each coat to dry. Tru Oil dries in 2 to 4 hours.
Surface Preparation Before Finishing
Before applying the Tru Oil, it is crucial to prepare the wood surface thoroughly well. A poorly prepared surface will not be made better by the finish; rather, it will make the issues worse. The bulk of the preparation involves sanding to get rid of any flaws and smooth up the surface. You should finish with finer sanding, like 220 or 320 grit.
You should start with coarse sandpaper and work your way up. When you apply Tru Oil finish on top of the Tung Oil layer, there is no need to sand down unless there is substantial surface damage or dirt. So long as the original Tung Oil finish is dry and clean, you can proceed to apply the Tru Oil finish for a nice protective glossy finish.
Applying Tru Oil to the Wood
You should apply the finish in small sections and spread it out until it thins out. Basically, the rule of thumb is that you should not be able to see how thick the finish is on the wood surface; it should almost appear as though the wood is just moistened.
When the pad runs out of oil, dab some more Tru Oil from the bottle and continue increasing the area of wood where the finish has been applied, it can be placed aside to dry before the next coating once the entire piece has received a consistent coat.
The oil should look like it has been absorbed into the wood rather than leaving a coating of water-like residue on the surface. Thinly coating the wood will help it dry more quickly and allow you to treat it again more quickly. The true trick is that it will also level itself.
If you have to work twice as hard and take an extra half a day to smooth out the finish you just applied, then you are wasting valuable time.
Drying Times and Curing
For a second coat, Tru-Oil needs to dry for roughly 2-4 hours; in cold, humid areas, this process is longer; in warm, dry climates, it is shorter. You can check by touching the surface after a few hours; a finger must be able to move freely without getting stuck. Additionally, the coating is still wet if the item still has a strong odor.
Another important thing is that the work should be left in a well-ventilated area. A tiny fan to move the air around also helps, but you should not blow it around too much. Dust should not be allowed to touch the freshly applied finish.
In sum, Tru Oil and Tung Oil are both finishes that are used on wood. The fundamental distinction between Tung Oil and Tru Oil is that Tung Oil allows someone to get the natural feel of the treated wood, but Tru Oil can provide a tougher, more varnish-like surface.
There is a reason why Tru Oil is preferred over Tung Oil and also why you would want to add it as a finish on top of the Tung Oil finish; both are used to protect the wood from moisture, but Tru Oil offers more resistance because of the stacked layers that prevent the wood from absorbing any moisture.
Additionally, Tung Oil takes way longer to cure, usually a day for every application. This can be inconvenient due to time constraints apart from being a more laborious exercise. It is rather easy to choose between these two treatments. It all comes down to how much time someone has and how much shine they want. If you want a quick-drying bright finish, Tru Oil is the better option than Tung Oil.
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