How to slow drying time of acrylic paint?
Summer is coming, and that means one thing – the already fast-drying acrylic can start drying even faster. I’ll tell you what to do about it in this article.
Acrylic paints dry mainly by evaporation of water. The hotter and drier the room you are painting in, the faster the water leaves the paint layer and moves into the air. And the faster this happens, the less evenly the acrylic dries, which can lead to cracks in the paint layer if you are dealing with liquid acrylics. If you are painting with a paste technique or your idea requires a thick acrylic, the rapid drying of the paint can be a real challenge for the artist. What can be done about it?
1. Increase the humidity of the room
suitable for: heavy body/soft body/fluid acrylics
In my studio there is a small thermometer-hygrometer, with which I monitor the humidity of the room, especially in winter, when the central heating literally dries the air to desert values (20%-25%).
By increasing the humidity readings to 50-65%, even at slightly higher air temperatures, the acrylic will slow its drying, allowing the paint to dry more evenly. You can increase the humidity by using a humidifier.
In my studio, both winter and summer, the humidity stays around 50% due to the large number of plants.
2. Use additives to slow drying time
suitable for: heavy body/soft body/fluid acrylics
The second way to slow the drying of acrylic is to add certain specific mediums or retarders to it. I work mostly with liquid acrylics, and usually they don’t need additional drying retarders. But if the weather is hot for a long time and I notice that my liquid acrylics start to behave differently already at the pouring stage, I make sure to add a small amount of drying retarder. In addition to a commercial drying retarder, you can add glycerin to your acrylic.
The instructions for each additive usually state how much can be mixed with the acrylic. I usually add no more than 5% of the total volume of liquid paint. For example: in a 200ml cup of acrylic mixed with pouring medium on a hot day, I add about 5-10ml, depending on the air temperature and humidity.
If too much retarder is added, the acrylic will not form a strong film resistant to moisture or will not dry at all.
How do I use glycerin as a retarder? The easiest way is to mix it with a small amount of water, about 1 to 4, where 1 is glycerin and 4 is water, and then add a few drops to the acrylic. This way you are less likely to add too much glycerin.
3. Experiment with different brands and formulations
Different brands and formulations of acrylic paint have varying drying times. Explore different options to find paints that naturally dry more slowly. An example of such paints, which can be bought almost everywhere, is Golden OPEN acrylics, Winsor & Newton acrylics.
The drying time of Golden OPEN acrylics varies from 30 to 60 minutes when used straight from the tube. It is currently the longest drying acrylic paint on the market. Winsor & Newton acrylics take on average 20% longer to dry than other acrylic paints.
These tips are universal and apply to all techniques, whether you are working with thick colours that hold their shape like butter or liquid colours.
Adjusting the drying time of acrylics may take some experimentation and practice. Play around with these tips to find the methods that work best for your painting style and the conditions in which you paint.
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