Many artists have an issue with acrylic paint because it can become watery and thin. There are a few reasons for this which are explored here. I have had that happen from time to time and have found the following reasons and solutions.
There can be several reasons why your acrylic paints are watery. It could be because you haven’t used them in a while and the paint has separated. The type of paint you are using as some are more watery than others. The quality of your paint. Or even how you are mixing the paints with water.
I have explored each of the reasons given above in more depth along with some solutions where they are needed to give you a better idea of where your problem lies so that you can fix it.
Why Is My Acrylic Paint Watery & How To Sort It
If you are using a tube of paint and you open the tube and squeeze out the paint and find it is watery. Don’t worry there’s nothing to worry about most of the time.
This simply means that your paint has separated while it’s in the tube. This can be for different reasons. It could be the age of the paint. Acrylic paint does have a life of around 2 to 5 years once they have been opened. So if you have old paint that has been opened it may be time to get new paint. Try to sort it out before you throw it out. If it hasn’t been opened you should have approximately 8-10 years in which case it is more likely to be savable.
If you paint isn’t old or faulty there’s not a lot you can do with a tube other than squeeze out more and either ignore the watery bit or mix it back together again. I’ve done that in the past but find the first paint squeezed out is runny. Usually, the rest of the paint is fine.
If you have a bottle rather than a tube, shake the paint before use. This will work if you haven’t left the paint too long. The longer you leave it the harder it is to get the paint back to its original state.
Again if your paint is older this may be the issue.
How you store the paint also makes a difference in how well it keeps. You are supposed to keep them in an airtight container. This should be at a temperature of around 65-75F (18-24C). And do not keep the paints in a wet or damp location. (Source).
The quality of the paint makes a difference in how likely it is to separate. Cheaper paints are more likely to separate than better quality ones.
A note of caution though. I read somewhere that cheaper paints are the ones in the bottles. I have to admit I very much feel that this is true. In the past, I have avoided them because I think of them as school paints. However, this is not necessarily the case. I noticed that in some countries bottles seem to be the norm.
Also, a while back I took some courses with a US art school. They had created all their own range as they had a specific method that was difficult to do with normal acrylics (believe me I know, I tried). All of these paints were in bottles. They are artist quality paints. So please don’t assume that your paints are watery because they are in bottles and cheap. It may be for one of the other reasons mentioned here.
For example, the type of paint also makes a difference to how watery it is. Airbrushing (acrylic ink) paint is thinner than normal paint. So is acrylic craft paint. These are also in bottles and often look very similar to artist paint. It would be easy to get the wrong ones.
Why Is Your Acrylic Paint Runny
If you have runny paint and it is from the tube or bottle it could be one of the reasons given above under why your paint is watery.
If it is happening while painting it could be due to adding too much water while mixing your paint. Or you could have not wiped out your brush enough thus increasing the amount of water you are using. You should not use more than 50% of water to acrylic paint. Not only does using too much water or other diluting medium make the paint thinner and runny it weakens the paint’s integrity. This means that you could have trouble with peeling and flaking of your painting later on.
It could be your paint. Acrylic paint comes in different thicknesses or viscosity. It may be that you have a thinner viscosity paint. Some are very thick while others are liquid. Check the tube or bottle or if it doesn’t say there should be a write up about it online.
Can You Thicken Acrylic Paint? If So How?
If you are having issues with runny or watery paint and simply want to thicken your acrylic paint you can easily do this.
You can leave your paint out on the palette for a few minutes. Acrylic paint is extremely fast drying so the water will start to evaporate and your paint will thicken up. Be warned though this will reduce your painting time which is already short.
You can also get pastes and gels that can thicken your acrylic paints. You can buy these where you normally get your art supplies. You can also make them yourself. Although, I’d advise against it for beginners as if you have any issues you won’t know if it is the homemade mixture or something you have done that caused them.
To use pastes and gels to thicken your paint simply add them to your paint while painting.
What To Do If Your Acrylic Paint is Thin
When your acrylic paint is thin because you have added too much water (or other medium) it is easy to correct.
While thin and transparent paint is often the desired effect, when it isn’t and you want to thicken it, it is easy to correct.
The easiest way to thicken your acrylic paint back up is to add more paint to it. This will thicken and add some opaqueness to it. However, if you have not thinned it too much (more than 50%, manufacturers state 30%) you could also leave the layer to dry and then paint another layer of paint over the top.
You don’t have to add anything to acrylic paints to use them if you don’t want to. Use them from the tube or bottle this way this shouldn’t be an issue.
Again, the quality of your paints can be an issue. Some student paints do not have the strength of the artist ones. Student paints lack the viscosity and opaqueness of artists paints because they use more filler. This may be noticeable while painting. This is more noticeable with the cheaper student ranges. Either buy better student brands or go to artist paints.
If the paint is also transparent it could be not only because it is thinner but because most of the acrylic paints are not opaque which adds to the “thinness” of your paint. Most are semi-transparent or transparent. Check your tube color. It should have some indication of how transparent or opaque the paint color is.
Two ways to help with transparency is to add one of the opaque colors to your mix or to add a gel medium or paste. This not only helps with thin watery or runny paint but can help with adding some opaqueness to it.
Can You Water Down Acrylic Paint?
You can water down your acrylic paints. You can do this either by using water or an acrylic medium. You can use up to a 50/50 ratio of water to acrylic paint. However, the manufacturers recommend only 30% of water. Any more and you start to lose the paint’s integrity and it won’t bind together which can cause peeling of the paint on your picture.
There can be issues with this as shown above. You don’t have to water down acrylic paints to use them.