Tung oil is used to protect the wood surface and enhance its color. But, can you apply Tung oil over stain?
You can apply Tung oil to stain, but the coating must be fully dry. Tung oil sticks better to oil-based wood stains because they use the same solvent (oil). However, it doesn’t stick to topical or sealed stains.
A sealed stain will prevent the Tung oil from penetrating its coating, so the wood oil won’t stick. Even if it sticks, the finish won’t be durable. So, the durability of the finish depends on how well the wood oil sticks.
Tung oil sticks to regular (water or oil-based) wood stain. But, you must lightly sand the wood stain with fine-grit sandpaper before applying it.
However, Tung oil doesn’t stick to topical or sealed wood stains because they will prevent it from penetrating their surface. Since it can’t penetrate a sealed surface, the wood oil won’t stick. So, you must remove the topical or sealed stain from the surface before applying the wood oil.
Also, the stain coating must be thin for Tung oil to stick. That’s because Tung oil is a penetrating finish and must soak deeply into the wood fibers or grain to stick well. So, if the coating is thin, the wood oil can penetrate it and stick better. However, if the coating is thick, the wood pores will be full, so the wood oil won’t stick well.
To improve the bonding between these two finishes, sand the surface. Sanding creates tiny ridges that the wood oil can penetrate to. Also, sanding removes some parts of the finish, allowing Tung oil to stick better. To sand, use fine-grit sandpaper.
How To Apply Tung Oil Over Stain?
Before applying Tung oil over a stained surface, you need the following tools:
- Fine-grit sandpaper
- A degreaser
- An angled paintbrush
- Clean lint-free rags
- Tung oil
1. Clean and Degrease The Stain
First, clean and remove grease from the stain coating. Grease will prevent Tung oil from sticking properly and can taint the finish.
To clean it:
- Wipe the surface with a degreaser.
- Use a rag to remove dust and clean the wood.
- If the finish is sealed, use a paint stripper to remove it.
2. Sand The Stain
Once the wood stain coating is dust-free, sand it with fine-grit sandpaper. Sanding will remove imperfections from the surface, create tiny ridges and allow the wood oil to penetrate the coating.
Sand the wood with fine-grit sandpaper and not coarse-grit sandpaper. Coarse-grit sandpaper will remove the wood stain coating and scratch the wood. After sanding, remove dust and debris from the surface with a clean rag.
You can also wet-sand it, but you must wait a few hours for the surface to dry. So, dry-sanding is a faster alternative.
3. Apply The Tung Oil
Once the wood stain coating is clean and sanded, apply the Tung oil:
- Pour Tung oil into a clean bowl.
- Dip a clean lint-free rag into the bowl.
- Use the dampened rag to apply the Tung oil.
- Rub the wood oil over the surface by moving the rag in a circular motion.
- Apply 3 coats of Tung oil over the stain coating.
- Wait until one coat dries before applying the next one.
- Use an angled paintbrush to cover tight spots and corners of the wood.
4. Wipe The Excess
You must wipe the excess from the wood surface. If you don’t wipe it, the finish will turn sticky (or tacky). After you remove the excess oil, allow the Tung oil to dry for 3 days before using the surface. Optionally, you can seal it with a sealant after it dries.
Tung Oil Darkens The Finish
Tung oil doesn’t cause the wood stain to turn dark; it only makes its color appear deeper. Its finish is thick and doesn’t allow light to pass through easily. Since it reflects low light, the stain or wood color appears darker. However, if the Tung oil is removed, the natural color of the wood returns.
The Tung oil finishes develop an amber (gold-like) shade after a while. This is because of the high amount of oil the wood oil has. Once the wood oil starts to dry fully (cure), the oils in the finish get dry and create an amber (or light gold) finish.
To make the finish appear lighter, thin it with mineral spirits (up to 50%). This makes the Tung oil flow lighter, doesn’t deepen the color of the stain, and makes it easier to apply.
Different Types of Stains:
Here are some different types of stains that you can or can’t apply tung oil over:
Water-Based & Oil-based
You can apply Tung oil over a water-based stain, but the coating must be fully dry. Optionally, you must sand the coating to improve the adhesion.
You can also apply it over oil-based stain because it has a high volume of tree oil, so it’s compatible with Tung oil. However, you must sand off (remove) the glossy layer of oil-based stain to allow the Tung to penetrate. If you don’t, the glossy layer will prevent the wood oil from penetrating its coating, and the wood oil won’t stick.
You shouldn’t apply Tung oil over the Miniwax stain. That’s because Miniwax stain is also a penetrating oil finish and will fill the wood pores. So, if you apply Tung oil over it, the wood oil won’t be able to penetrate and won’t stick.
You shouldn’t apply Tung oil over Gel stain. That’s because Gel stain is a penetrating finish that can’t be painted over. When dry, it forms a moisture-resistant coating that repels liquid, including wood oil.
You can apply Tung oil over a regular stain, but the stain shouldn’t be sealed. If the wood stain is sealed (or has a glossy finish), you must remove the glossy top layer before applying it. Also, you must sand the coating to increase the adhesion between both finishes.
Tung oil is a penetrating finish and must penetrate a surface to stick. If it can’t penetrate a surface, it won’t stick.