Tung oil is known for two things: its highly protective characteristic and its nature of taking forever to dry. Unlike other finishes, tung oil requires a special application to ensure that it will be absorbed by the wood efficiently. However, many woodworkers often face the dilemma of tung oil not drying. It’s frustrating and can be a deal-breaker for those working on a big project.
In this post, I will tackle the problem and give tips on how to make your tung oil finish dry properly.
Why is my tung oil stain not drying?
If your tung oil isn’t drying, the following might be the reasons why:
It just needs more time
Pure tung oil takes about two weeks to fully cure. This means that even if the surface looks dry, the inside will still be wet. Giving your project a few more days to dry should help. If you have a project that uses tung oil, you must dedicate two to three weeks for the finish to dry.
Over-application of tung oil
If it has been two weeks and your tung oil finish still feels tacky, you probably applied too much.
Each wood type has varying absorption levels. Once its pores have been soaked with oil, the rest would sit on the surface to dry. However, applying too much will cause a thick layer of oil to sit on the surface and not dry fully.
This is why you should be modest on every coat of tung oil you use. Keep it thin and let the coat dry first before applying another. This way, the tung oil won’t remain tacky and wet.
High humidity levels
Tung oil is best dried in a warm and dry place. If the humidity in your area is high, the oil won’t cure properly. The same goes for cold weather despite having low humidity levels. As much as possible, you need to avoid damp conditions when applying tung oil to your project.
Slow-drying tung oil
Many manufacturers produce their own tung oil blends. Some dry faster, while others take more time than usual. And since tung oil is a natural finish, it’s normal to expect longer drying periods.
It’s best to check the label of the tung oil before using it. This way, you can prepare for the drying time as well as the proper application to prevent a tacky finish.
How to fix tung oil that’s not drying
If you’re dealing with a tung oil coating that doesn’t seem to dry, the following tips will help:
1. Strip and re-apply the finish
If you have the time, the best way to fix a botched tung oil finish is to redo it.
First, you can strip the tung oil finish by applying a mineral spirit. This will thin the oil and allow you to wipe it out of the wood.
Once the finish is removed, you should dilute equal parts of turpentine and tung oil. Re-apply this finish and let it dry. Unlike pure tung oil, those diluted in other oils and thinners will dry faster. You may need to re-apply a few more coats to achieve the color that you like.
2. Apply a wood restorer
If it’s too late to strip the tung oil and start over, the best option is to use a wood restorer. You can purchase this at almost every supply store, with most products made for flooring. It’s a convenient option and a less harsh solution if your tung oil finish isn’t drying.
To apply this solution, you should use extra-fine steel wool to rub it into the wood surface. The fine steel wool will create minuscule abrasions on the stain to allow the wood restorer solution to penetrate the wood and oil.
This method will help blend away tacky and gummy tung oil spots on the wood. If you’re also dealing with uneven stains, this is an effective fix.
If this is your first time using a wood restorer on tung oil, you should test it on a hidden corner of the wood. This way, you can assess how the product will react to the finish.
3. Use a dehumidifier
If you don’t want to touch or undo the finish, you can try using a dehumidifier to speed up the drying process of the tung oil. You should place your workpiece inside a warm room then run a dehumidifier at the same time.
By keeping the air dry, the tung oil will likely cure faster. However, this solution will have varying results, depending on how thick the coat is and the specific tung oil product you used.
How long does it take for tung oil to dry?
Tung oil will usually take two to three days to dry on the surface. But for the entire curing process to finish, you need to wait for two weeks. Some tung oil blends can cure faster than pure ones.
If you want tung oil to dry faster, consider diluting it with mineral spirits. You can also look for a quick-drying finish to save you from the hassle.
How long does it take for the tung oil smell to go away?
Tung oil has a nutty smell, which is similar to other natural oil finishes. This odor isn’t repulsive, but it usually lingers for up to two weeks after being applied to wood. Depending on the wood type you’re using, the smell may stick for a month.
Nevertheless, the scent of tung oil is harmless and won’t cause irritations the same way as VOCs do.
However, if you diluted the tung oil with mineral spirits, you should expect it to smell stronger. You should aerate it well before using the wood. Remember that surfaces treated with thinned tung oil aren’t food-safe.
How many coats of tung should be used?
For maximum wood protection, I recommend applying at least 3 to 5 coats of tung oil on any wood you’re working on. If you don’t have the time to spare for lengthy drying, 2 to 3 coats will do.
Aside from that, the number of tung oil coats depends on the color you want to achieve. More coats mean deeper colors.
At what temperature do you apply tung oil?
Tung oil is best applied at temperatures between 50F to 90F. It’s the same temperature you need to maintain during drying time. The warmer it is, the better it would be for the oil finish. Still, you should avoid extreme heat as it may cause the oil to react harshly on wood.
In general, you need to apply tung oil above the freezing point since this oil polymerizes fast. Also, the cold temperature will cause the fat in the tung oil to separate from the rest of the substance.
Can you spray tung oil?
Tung oil is thick and should never be sprayed. You should only brush it in or use rags to wipe it into the wood. Trying to spray tung oil won’t just ruin the finish, it will also clog your sprayer. This would apply the same even if you thinned the tung oil.
Can tung oil go rancid?
Tung oil can go rancid if the container is left unsealed. As the oil gets exposed to the air, it hardens and loses its consistency. The same thing will happen if the raw oil is exposed to extreme temperatures. But once tung oil is applied on wood, it won’t go rancid as long as it dries well.
Generally, tung oil finishes have a shelf-life of around two years. After that, you should toss the old cans into the bin and get fresh ones.
A case of tung oil not drying is frustrating, especially if it occurs on a big project. You have several options to fix the botched stain work, but redoing the finish is still the best way to go. Knowing your oil and wood is also crucial to prevent drying problems.