How can I slow down the drying time for acrylic paint?

Acrylic paint is widely used by hobbyists as it offers many advantages. It is water soluble which removes the need for hazardous and flammable thinners and cleaners, also it is produced by a wide range of manufacturers and so is relatively abundant and cheap. For those modellers who are new to acrylics its fast drying time may come as a bit of a surprise. This can be problematic, especially when painting large areas as tonal and textual variations can occur as a result of its rapid drying time.

As a result, there are a few ways to slow down the drying time for acrylic paint:

Add a paint extender or retarder to the paint: These products are specifically designed to slow down the drying time of acrylic paint. They can be added in small amounts to the paint to give you more working time. This is especially relevant to airbrush users, as the airflow that delivers the paint to the subject further increases the drying rate, resulting in the paint drying on the airbrush needle. This can disrupt the airflow and result in an uneven paint job. Adding a flow retarder or extender allows the paint to self-level on the model before drying, thus ensuring more even coverage.

Use a humidifier: Acrylic paint dries faster in dry air, so by adding humidity to the air with a humidifier, you can slow down the drying time.

Keep your paint in a cool, shaded area: Acrylic paint dries faster when it's hot and in direct sunlight, so keeping your paint in a cooler and shaded area can help to slow down the drying time.

Cover the paint with a wet cloth or plastic wrap: Covering the paint with a wet cloth or plastic wrap can help to slow down the drying time by keeping the humidity level high.

Keep your brushes and palette wet: If you're using acrylic paint, it's important to keep your brushes and palette wet. This will help to slow down the drying time by thinning the paint slightly and increasing its water content. This additional water will take a little longer to evaporate, thus slowing down the drying time and making your paint easier to work with.

It's important to note that some of these methods may affect the final result of your paint job.  It is a good idea to test them out first on scrap material to see what works best for you before entrusting them to your model.