Oil Paint is one of the most widely used mediums for artists to use. It takes much longer to dry than other painting mediums such as watercolour, acrylics or gouache paints.
The benefit of such a slow drying time means that artists have much longer to manipulate paint and blend colours giving the paintings a much smoother, buttery appearance.
There are many questions that people have regarding the drying time of oil paints, but firstly, does oil paint actually dry? The short answer is yes oil paint does dry eventually but there are many variables that effect the drying time of oil paints.
In this post I will be covering the main factors that affect the drying of oils and some ways in which you can change the drying time of your paints.
Does Oil Paint Dry?
Oil Paint does dry eventually but it can take years for an oil painting to be completely dry. The surface of an oil painting may become touch dry after a few days but the paint underneath may still be wet. For complete drying some paintings may take months to dry whilst others can take many years. This can be due to many reasons such as;
- The temperature
- The amount of light
- How thick each layer of paint is
- How much and which medium was used
- The quality of the paint
- The colour of the paint
- The brand of paint
Why does oil paint not dry?
Oil paints do not dry like regular paints. Acrylics and watercolours dry because the water inside of them evaporates. Oil paints ‘Dry’ through a chemical reaction known as oxidation. When the wet paint gets exposed to oxygen in the air the drying reaction happens.
The surface layer of paint is in contact with the air so the oxidation process happens relatively quickly and the surface of the painting can be ready to work on again after around 24 to 48 hours.
For most oil paintings it is important that you wait for the layers to be completely dry before you start painting on top of them. If you do not wait long enough you run the risk of lifting paint off the canvas and damaging the layers underneath.
How to check if an oil painting is dry
There is a simple test to check if your oil painting is dry all the way through. Run your fingernail gently across a small section of your painting. Don’t press too hard you don’t want to go through to the canvas with your nail!
If the small bits of paint that come off are powdery or dust then the painting is dry enough to work on top of. The painting is still wet underneath if the paint comes off like a thread.
Can you dry oil paints with a hairdryer?
It may seem to be a good idea to use a hair dryer to dry oil paints. But it will not work very well.
As oil paints dry because of oxidation reactions the evaporation of water caused by the heat of the hairdryer will not speed up the drying time and may even cause your painting to crack.
The hair dryer may work a little bit as the heat will increase the temperature and the oxidation reactions will happen faster and so the painting will dry a few minutes faster however it would not be enough to really impact the drying time.
The hairdryer may also cause mineral spirits and paint thinners to evaporate faster. The actual oil paint that is left will not dry much quicker because of the hairdryer. This could lead to the release of excess solvent fumes in the air which could be hazardous to your health.
Do different oil paint colours dry faster?
The straight forward answer is yes, the colour of the oil paint you are using will influence how long it takes your painting to dry.
The different colours have different drying times. Oil paints are made of a pigment which gives it colour, oil and a binding agent mixed together. Different pigments, binding agents and oils can be used that effect the drying time of each paint.
The earthy browns are some of the fastest drying paints. They can sometimes take less than a day to dry if applied thinly to the surface. Raw umber is a perfect example of this.
Umber is a pigment that also contains a natural oxidising agent known as manganese which helps speed up the drying time of this particular colour as the oxidation reaction happens much faster.
Raw Umber is commonly used for under-painting sketches and block ins because it is one of the fastest drying oil paints.
Some other fast drying colours are
- Burnt umber
- Cobalt blue
- Raw sienna
- Burnt sienna
Why do some oil paint colours take longer to dry?
The reasons why some of these paints take longer to dry is because of the amount of pigment or the amount of oil present in each paint. It is a complicated matter and is influenced by many factors but the general rule is that the more oil present the more time it takes for the paints to dry.
The paints that take the longest time to dry are
- The reds such as cadmium red and alizarin crimson
- The yellows; cadmium yellow, Naples yellow
- The blacks; Mars black, lamp black, Ivory black
- Titanium white
Basically any oil paint that is transparent, cadmium or a hue will contain lots of oils and as such have a longer drying time. And as such aren’t often used in the base layers of a painting in very large amounts.
How to speed up the drying time of Oil paint
When oil painting there are a number of things that can be done to speed up the drying time. Some are in our control others are not.
Leave your painting in a warm environment this will increase the rate of the oxidation reactions and your painting will dry faster.
You could also use Oil mediums, Alkyd mediums or paint thinners.
Which Paint thinner is best?
When painting in oils you will need to use a solvent to thin your paints and clean your brushes afterwards. Some common thinners that artists use are turpentine and Mineral spirits.
Turpentine is the more historically used thinner. It is made from the resin of trees. It is incredibly flammable and emits vapours that can be hazardous to skin, eyes and lungs.
I believe a better alternative are mineral spirits made from distilled petroleum. It is important for painting that you use an Artists mineral spirit and not just white spirit from a DIY shop.
Mineral spirits are less flammable and the vapours are less toxic than those released by turpentine.
They do still release fumes that can cause headaches and nausea so it is best to use them very sparingly in very well ventilated studios.
One of my favourite Spirits on the market is Gamsol. It is a low-odour solvent and I have had no problems with it causing headaches or irritating my skin. I do still recommend using nitrile or latex gloves when painting in oils though just in case.
Which Oil medium is best for drying?
There are many different oil mediums available when oil painting that you can mix with your paint to make it more malleable and fluid.
Some of the most common are Linseed oil, Poppy and Walnut oils, Stand oil and Safflower oil. All of the oils will slightly extend the drying time but linseed oil is the fastest drying oil medium.
Oil mediums can be used to increase the transparency of the paint. This means that the paint can be used for glazing colours and details. This medium is used in the final layers of a painting.
It is recommended that you do not use oils in the initial stages of the painting instead save them for the final layers and use mineral spirits at the start to thin your paints.
What are alkyd mediums?
Alkyds are an alternative medium that you can use when oil painting instead of using oil mediums like linseed oil. The oils slow down drying time but Alkyd mediums make oil paints dry faster.
Alkyds are made from modified resin and treated with alcohol and acids which is where the name comes from.
Alkyd mediums are very fast drying they can reduce the drying time for a layer of oil paint to 18-24 hours meaning the work can be ready to paint on the next day.
Alkyd mediums do not yellow paints whereas some oil mediums like linseed oil can yellow paler colours. Alkyds are used very similarly to the oil mediums for glazing purposes. They speed up the drying time whereas the oils slow it down.
One of the most common alkyd mediums available is liquin or Liquin original. Liquin is a Semi-gloss medium that speeds up the drying time of the paints. It is great for glazing and detail work as it improves the flow of the paint and reduces visible brush strokes.
As it dries the surface becomes a hard enamel which can be pleasing to view. The alkyds cause the paint to dry darker and give it a plastic like finish similar to acrylic paints.
How to dry oil paint faster
So we now know that using different colours of paint, different oil mediums and alkyd mediums can affect the drying time of an oil painting so choosing the correct paints and mediums is the biggest and most important step when trying to decrease your drying time for a painting.
Here are a few final tips that you can do to help speed up the drying time of your oil paintings.
- Paint on an even surface, cracks and crevices can cause paint to build up and take longer to dry
- Start your paintings with faster drying paints like raw umber.
- Start your paintings with thin layers using solvents instead of lots of thick oil paint.
- Use fewer layers the more layers you use the longer it will take for them all to oxidise.
- Dry your painting in a room with good air circulation or a fan so plenty of oxygen can reach the paint
- Make sure the room is not too humid use a dehumidifier if you have one
- Make sure the room is warm a higher temperature means faster oxidation reactions.
- You could also use a UV light or leave your painting in the sun however this can lead to bleaching of the painting causing it to turn whiter.
Thank you for reading and I hope you find this useful for your next painting. If you have any questions please leave a comment below and we will get back to you!
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