Milk Paint vs. Chalk Paint: Which Is Greener?

If you’re looking for paint that will beautify your living or working space while treading lightly on the planet, you’re in luck. Milk and chalk paints are fast-drying, water-based paints that are easy to acquire, easy to use, and easy on Mother Earth. 

In contrast to oil- and latex-based paints, neither milk paint nor chalk paint releases volatile organic compounds (VOCs), carbon-containing chemicals associated with increased ozone levels and respiratory illness.

Here, we peel back the layers of paint to decide which one gets our green star of approval.

What Is Milk Paint?

Touted as “paint for the ecologically-minded,” milk paint is made from simple, natural ingredients: casein (a protein found in cow’s milk), calcium carbonate (also known as lime or limestone), pigment, and sodium borate (a preservative, commercially known as Borax). 

This mixture of ingredients is usually sold in powder form to be mixed at home (although you can find it pre-made in an airtight container). Painting on a non-porous surface requires that the milk paint formula include a bonding agent to help with adhesion. 

Adding water to the milk paint powder causes a chemical reaction between the casein and the lime, giving the paint its sticking power. 

Advantages

Milk paint doesn’t require a primer or a sealer, and it applies well to many surfaces. Compared to its oil and latex counterparts, milk paint dries very quickly—in less than half an hour rather than an entire day. 

Best of all, this biodegradable, non-toxic paint faintly smells of cut grass instead of the chemical odor of petroleum-derived paint, making it safer and more enjoyable for painters to work with.

Milk paint is also durable and particularly useful in projects that require intense color saturation with a low-level sheen. Designers who work with the shabby chic aesthetic praise milk paint for its mottled, distressed texture. 

Disadvantages

Milk paint is not designed for long-term storage. Once mixed with water, it can last a few days if refrigerated in a sealed container, but it’s best if used within 24 hours. Because of this, milk paint is most appropriate for small-scale projects rather than large ones, like walls. 

Although milk paint doesn’t require a sealer, an extra layer of protection can prevent dings and discoloration if you’re painting a high-traffic, high-use area or object. The sealant source may include animal products like beeswax, fossil-fuel products like oil or polyurethane, or more sustainably sourced hemp or walnut oil (although those require more drying time). 

Since milk paint comes from dairy, it’s unsuitable for vegans. Environmental vegans point to dairy being responsible for 2% of greenhouse gas emissions worldwide as part of their reason for choosing a plant-based lifestyle.

What Is Chalk Paint?

Chalk paint is a thick, water-based paint also made from calcium carbonate and pigment mixed with water. Like milk paint, chalk paint works on virtually any surface. But unlike milk paint, chalk paint has a more matte finish and requires a topcoat if you’re looking for something other than a lightly gritty texture.

Advantages

Chalk paint is typically sold pre-mixed, saving you time and energy as it can be challenging to get the lumps in milk paint to break down completely. This nonorganic, primarily non-toxic paint also contains no animal products, making it vegan-friendly. 

Chalk paint dries in less than an hour and has no smell whatsoever. It can also be stored for long periods without compromising the quality of the paint.

Disadvantages

Chalk paint is more susceptible to damage than milk paint, so adding a topcoat can help prevent problems from happening in the first place. Because most chalk paint is pre-made, the colors are limited to what is commercially available, unlike milk paint, where painters can easily mix powders to create entirely new hues. 

Some varieties of chalk paint can also contain toxic ingredients and VOCs; check the label before purchasing. Lastly, chalk paint is more expensive than milk paint.

Which Is Greener?

This battle is difficult to call because both of these paints offer many advantages over fossil fuel-based paints. Since we have to choose, we opt for chalk paint because it doesn’t require any dairy products and because zero-VOC chalk paint is commercially available. 

The ingredients in the two paints are so similar that the most significant consequence of selecting chalk paint over milk paint is that the range of colors might be smaller, and the price might be a bit higher than anticipated. 

Whichever you choose, these low-VOC paints are preferable for people and the planet.