Oil finishing problem with linseed oil and tung oil
In this article, you will find several linseed oil tips and tricks that can prevent potential problems.
What sometimes goes wrong?
Occasionally, however, something goes wrong, which is annoying for you, so we want to prevent this as much as possible.
Below you will therefore find an overview of the problems that we occasionally encounter and what the solutions are.
Oil drying time problem
almost all cases reported that oil needs a (much) longer drying time than we indicate.
The cause of this problem is again in almost all cases that customers have applied the oil as if it were varnish and did not polish the surface, assuming that a layer twice as thick will probably be twice as good.
Nothing could be further from the truth. The purpose of an oil finish is to bring oil into the wood, not to put an oil film onto applying the wood.
With some products from other brands, it is no problem to apply a thicker layer or not polish the oil because they contain a serious proportion of solvents that evaporate during drying, resulting in a thin film Staying behind.
For oil that contains little or no solvents, a layer of oil is applied to the wood; the part of the oil that is no longer absorbed by the wood will remain behind on the surface as a kind of varnish layer.
If the top of that oil film starts to dry (which happens pretty quickly), a sealing layer is formed on the surface that you can compare with a kind of plastic bag.
This sealing layer makes it very difficult for the oil underneath to absorb oxygen, severely delaying drying.
As the dried layer thickens, the “plastic bag” during drying makes it harder and harder for the bottom oil molecules to dry.
So the effect is that an oil film twice as thick needs four times or more to dry, three times as thick oil film nine times, and so on.
The general procedure is therefore as follows:
Apply thin
soak in for about 30 minutes, so the wood has time to absorb what it can absorb.
Then, wipe the surface with a clean, dry cloths polish.
Please note: The 30 minutes mentioned here and on our cans are based on normal temperatures of approximately 20 degrees.
At higher temperatures, the oil dries considerably faster and should therefore be polished off much faster; at significantly lower temperatures, the oil can remain in place for longer.
Therefore, it is important to process the oil under normal conditions and set up a test piece at the start of the work to determine the best time to start polishing.
For that reason, DO NOT apply the oil IN THE SUN and, as mentioned, always make sure that NO OIL STAYS ON THE SURFACE.
If your cloth becomes saturated during polishing, you will, of course, take a new, clean cloth.
So you start polishing while the oil is still wet; do not wait until the surface has begun to form a skin as that does not make polishing easier and quickly gives an irregular surface.
When you work in this way, you create an even oil film on the surface, which is the intention.
Problem with oil residues drying up
We occasionally hear that people have an opened can left, and when they want to use it again, after some time, they find that the remaining content has dried up in whole or in part and has become unusable. Of course, it is a waste of the product and the money.
The cause of the drying up is the fact that the remaining oil in the Can will react nicely with oxygen, as we have taught the oil.
If there is enough oxygen in the Can, the oil can form a neat film as intended, but you will probably be less enthusiastic about as long as the oil is still in the Can.
To somewhat reduce this shortcoming, we have included a “skin-firming preventive agent” with some products.
This is not solving the problem, but it does reduce it somewhat. If we were to absorb too much of that, the oil would no longer dry in the wood, and that is, of course, not the intention.
Old-fashioned solutions to prevent oil residues from drying out are to pour them into an empty jar or bottle that is so large that the oil comes almost to the edge and there is very little room for oxygen in the bottle left.
No oxygen? No drying! However, the best solution is to pour it into a StopLossBag immediately after opening a new can.
Those who feel more comfortable with the old-fashioned solutions can choose from the following alternatives:
- Squeeze the Can so that the oil is just below the cap to remove the excess air.
- Fill the Can with marbles or other non-absorbent materials to fill the free space above the oil space.
- Pour the remaining oil into wine bottles and draw a vacuum with a Vacuvin vacuum pump.
- Store the oil in a harmonica bottle such as those mostly used by photographers.
- Pour the oil into a cleaned milk carton that can be squeezed shut before screwing on the cap to expel the oxygen.
Reactions with other products
linseed oil that has been developed to be applied to untreated wood. While oil finishes do not normally react with each other, occasionally, products from other manufacturers will react, causing the finish to shrivel, wrinkle, or peel.
If your surface has already been treated with another product, first do a test piece at an independent place to see whether or not the previous product likes each other.
This will prevent possible problems and the associated work.
Reactions with ingredients
One piece of wood differs from another in many ways, and two pieces of oak, for example, do not always react the same.
It also applies here that it almost always goes well. Still, that mother nature sometimes apparently has a crazy mood in which she makes wood that reacts spontaneously with finishing products so that the result can, for example, turn out darker than usual.
The following also applies here: make a test piece before treating a large surface. You can then get used to the products and the working method yourself and be sure that nothing crazy happens.
How many layers do I need?
You will often find a text in which you are told to apply it on the cans, for example, 2, 3, or 4 layers of the product in question.
You will not come across such a concrete text in our eyes, but at the most, we will tell you that “in general, one layer is sufficient.”
This is because it is impossible to give a concrete answer to how many layers you should apply. After all, it depends on the desired degree of protection and the specific piece of wood.
The purpose of an oil finish is to saturate the wood with oil. Once the wood is saturated with oil, it can no longer absorb new oil, and if it can no longer absorb oil, it can no longer absorb rainwater, coffee, or vegetable soup, so we have the protection in order because wood cannot.
Getting wet will not stain and will not rot. The aim is, therefore, to apply as many layers until the wood no longer absorbs anything.
The general method of processing oil is:
Apply the oil thinly: let it soak for about half an hour. Places that easily absorb the oil during that time should be treated again immediately.
After half an hour, but in any case, before the oil starts to dry, wipe the surface with clean, dry cloths so that no oil remains on the surface
Let the sheets dry spread out to prevent overheating.
If necessary, apply subsequent layers after waiting a day and apply as many layers until the wood no longer absorbs anything and is therefore saturated.
So there will come a moment when you are polishing it that you think: Well, I could have left this layer behind; I am now polishing everything I just smeared on it.
And that is precisely the intention because when the wood is full, it can no longer absorb oil and therefore no longer absorbs water and other misery.
- You do not apply 1, 2, or 6 layers, but as many layers as are necessary to complete to saturate.
- Neatly sawn with the grain of a dense wood will probably have enough with one layer.
- A cutting board made of end-grain wood may need 15 layers before it is completely saturated.
The number of layers depends on the desired protection.
The protection for a TV cabinet that is only a little cozy and looks good in a nicely heated living room does not have to be as solid as the protection of a garden set that can be used outside in all kinds of weather.
We immediately process the proverbial TV furniture with undiluted oil and will typically need a layer or 2 to become saturated.
We naturally want to pump as much oil into the wood as possible for the outdoor furniture because the thicker we can make the oil film in the wood, the more robust the protection becomes and the longer the wood will last.
We often start with either Impregnation Oil or a diluted variant of the oil for those applications.
- Apply first coat of Improved Wood Oil diluted with approximately 30% Turpentine Oil
- Apply a second coat of Improved Wood Oil diluted with approximately 10% Turpentine Oil
- Apply subsequent coats of Improved Wood Oil undiluted until the wood is fully saturated
Diluting the oil or not is an exact science. Still, it simply works as follows:
The more diluted, the deeper the oil will penetrate, the thicker the final oil film, and therefore, the better the ultimate protection will be.
More layers will be needed to saturate the wood fully, and, therefore, more work and material are required.
Fabric and patches
When drying natural oils such as linseed oil and tung oil, heat is released, which can cause rags and fabric to heat and ignite spontaneously.
So always make sure that you spread out rags with which a natural oil has been polished out to dry and are not crumpled up in a wad.
In addition to the rags, heating can also occur in sanding dust, especially if an oil layer has been sanded with a machine, releasing a lot of heat.
So also make sure that the sander’s dust bag is emptied immediately and disposed of appropriately to prevent fire. Anyone who takes these simple measures can work happily and safely with natural oils.
Surface discoloration
Linseed oil products are yellow in the short term and turn black in the long term, clearly visible, especially with light woods.
Tung oil does not know this yellowing and blackening. Because a high-quality oil penetrates deep into the wood, this makes the fibers transparent so that the wood always becomes darker.
How much darker the wood gets depends on the type of wood. In addition, the wood can become darker because the surface is not sufficiently dust-free after sanding.
The remaining dust then absorbs oil, making each dust particle slightly darker and thus giving all dust particles together with an extra darkening effect. In short:
If you are working with new products for the first time, always make a test piece first to see the effect.
Make sure to clean the surface thoroughly after sanding and before applying the oil. This gives a less messy surface, works more pleasantly, and prevents unnecessary darkening.
How to prevent a problem with oil finishes?
For example, if you want to oil beams above a beautiful floor, it is wise first to cover the surface with plastic foil.
If oil does get on somewhere where you did not think so, it can be removed immediately with linseed oil soap or turpentine oil.
Do not let the oil dry out because then only physical removal is possible. The oil that has been diluted with Turpentine oil penetrates even deeper.
So do not be too frugal with the Turpentine oil and make sure that the oil is completely gone before leaving the accident site and allowing the oil to dry through.
But as mentioned, prevention is, of course, much better than cure.
