Does Glycerin Work as a Retarder for Acrylic Paints?

Glycerin May Not Be the Best Extender for Your Acrylics

Full Frame Shot Of Colorful Acrylic Paints

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Acrylic paints will often dry faster than you like and that is why painters often turn to retarders or extenders. These additives can keep your acrylics workable for a longer period of time because they slow down the drying process.

While you can buy retarders specifically for acrylic paints, many artists look for shortcuts or items that they may already have in their paint box. One of those that is commonly brought up is glycerin. It's useful for restoring dried up watercolors, but is it a good choice for acrylics?

Glycerin May Not Be a Good Retarder for Acrylics

There are a number of suggested 'alternative' retarders for acrylics circling on the internet. One of those recommends diluting glycerin with water then adding it to the paint. In theory, this should slow down the drying process and it will be okay to use because glycerin is already part of the paint. But is this really a good idea?

First of all, every painter must consider that all acrylic paints are not created with the same recipe. You will notice this if you switch from one brand to another and pay attention to the drying times of each. Glycerin may be in your acrylics, but by adding more, you're actually altering the manufacturer's 'recipe' for their paint.

This might not be a bad thing depending on the paint you use. Yet, as with all things artistic, the choice is yours, though you do run the risk of your painting's longevity. This means that your colors may not remain as vibrant and the paint may not remain stable for as long as it would with an 'approved' extender.

Acrylics may not seem like it, but they can be quite sensitive to chemical additives. You might not notice it today or this month, but the negative effects can appear over your painting's time.

What the Pros Say

Though the company also sells extenders, the tech support team at Golden Artist Colors does not recommend glycerin as an acrylic retarder. In testing, they have found that "glycerin will take a very long time to escape the paint film, especially thicker paint layers, and will allow the paint to remain tacky (not workable) for quite some time possibly for weeks or months."

This leaves your artwork vulnerable to dust that will permanently be stuck on the surface. You might also encounter unwanted mixing of colors when layering paints.

Besides, according to that statement, Golden notes that the acrylic is 'not workable,' it simply stays wet longer. This defeats the purpose of using a retarder so you can work with the paint longer. 

How to Better Extend the Working Time of Acrylics

Your best bet with quality acrylics is to purchase an acrylic retarder medium for acrylic paints. You spent the money on good paints, so why would you degrade them with an inferior product? The best part is that these mediums will not change the integrity of your paints. You simply get more time to work with them.

Consider your palette as well. It's often best to use a moisture-retaining palette with acrylics. You can also lightly mist your palette with water regularly. 

The alternative is to purchase paints that have a naturally slow drying time. Golden Open Acrylics, for instance, were designed for this purpose (and plein air acrylic painting) and can stay wet for up to two days. That's extreme though and most of the 'slower' acrylics will remain workable for around 30 minutes without an extender (or the breezes of plein air).