Making Watercolor Medium: The Clean, Natural Way
Medium is the name of the liquid we watercolor artists make so the ground pigments will stick to the watercolor paper. I have been changing my art studio over from the toxic commercial paints to ones I make myself.
In my latest video, "Making Watercolor Medium," I show you how to mix your own binder from scratch using food-grade, natural ingredients. If you’ve ever wondered what is actually inside commercial watercolor tubes—and why making your own is a game-changer for a non-toxic studio—let’s pull back the curtain.
What’s Inside: Your Handmade Binder vs. Store-Bought
While high-end commercial paints still use gum arabic, many modern mass-produced or student-grade paints rely on synthetic substitutes, petroleum-derived moisturizers, and harsh preservatives to survive years in hot warehouses and on store shelves.
Here is how a natural, handmade recipe compares to what is often hidden in commercial tubes:
1. The Glue (The Binder)
Commercial Paints: Many brands (especially student-grade) swap out pure gum arabic for Dextrin, a cheap processed starch made from corn or potato. While it works, dextrin can dry with a dull, matte, or slightly chalky finish.
Your Handmade Way: Pure, natural Gum Arabic—the hardened sap of the Acacia tree. It is completely non-toxic (it's actually used in food and candy!) and rewets like a dream.
2. The Moisturizer (Keeping it Soft)
Commercial Paints: To keep the paint from drying into rock-hard, un-brushable bricks, commercial paints often use Polyethylene Glycol (PEG), a synthetic, petroleum-based liquid.
Your Handmade Way: Natural Vegetable Glycerin combined with real Honey. Honey is nature's perfect humectant; it keeps the paint moist, adds a beautiful natural gloss, and helps the paint flow smoothly across the paper.
3. The Preservative
Commercial Paints: Because wet paint in a tube can easily harbor mold or bacteria, factories use powerful synthetic biocides (like parabens or phenoxyethanol). These can be harsh on sensitive skin.
Your Handmade Way: A couple of drops of pure Clove Oil. Clove oil is naturally rich in eugenol, a powerful organic fungicide that prevents mold and bacteria from growing in your paint. Plus, it makes your studio smell absolutely amazing!
Comparison at a Glance
| Ingredient | Your Handmade Binder | Modern Commercial Binder |
| The Base | Pure Gum Arabic (Acacia sap) | Dextrin (processed starch) |
| The Humectant | Natural Honey & Glycerin | Synthetic Glycols (petroleum-based) |
| The Preservative | Natural Clove Oil | Synthetic Biocides (harsh chemicals) |
Is Making Your Own Paint Better for You and the Earth?
Absolutely. When you control your medium and choose to paint with natural earth pigments and clays rather than heavy-metal-based paints, you are making a massive difference.
Avoiding Toxic Heavy Metals
Many traditional commercial colors rely on heavy metals to get their bright hues. Paints like Cadmiums, Cobalts, and Chromiums carry warnings because they can be harmful if inhaled as dry dust, and they accumulate in your body over time.
By mulling your own paint, you can choose to work exclusively with safe, natural earths—like Yellow Ochre, Raw Sienna, and Terre Verte. These are simply natural clays and iron oxides dug directly from the ground. They are completely safe to handle and contain zero heavy metals.
A Note on Studio Safety: Even when working with safe, non-toxic earth clays, dry pigment powder is incredibly fine and easily airborne. Always wear safety goggles to protect your eyes and a simple mask (like an N95) when scoop-measuring your dry powders, so you don't breathe in the dust or get it in your eyes before it gets wet!
Know Your Source: When sourcing natural earth pigments, only buy from reputable suppliers who third-party test their pigments for heavy metals and contaminants. Because earth pigments are dug out of the ground, they are only as safe as the soil they came from. Look for companies that certify their pigments pass strict heavy metal safety standards (like the EN71-3 toy safety certification, which ensures they are free from toxic metal migration). Never use random, untested raw dirt or cheap industrial pigments in your home studio!
The Environmental "Sink" Problem
Whenever we wash our paintbrushes, the leftover paint goes down the drain.
The Food Chain Connection: Heavy metals like cadmium do not biodegrade. In 2013, Sweden actually attempted to ban cadmium in artists' paints. A scientific study submitted to the European Chemicals Agency (ECHA) showed that when artists wash brushes under the tap, those heavy metals end up in wastewater treatment sludge. Because that sludge is often used as fertilizer on agricultural fields, those metals can slowly leach into agricultural soil and enter the food chain.
The Biodegradable Solution: When you use a handmade binder (sap, honey, glycerin, water) mixed with tested, natural earth clays, your leftover paint water is 100% biodegradable. It can go down the drain—or even be poured out on your garden flowers—with absolutely zero harm to the environment.
References & Further Reading:
On Paint Chemistry & Ingredients: Handprint: Watercolor Materials and Chemistry (Bruce MacEvoy) details the use of synthetic glycols, dextrin fillers, and traditional gum arabic solutions.
On Clove Oil as an Art Preservative: Natural Pigments / Rublev Colours documentation on the properties of Eugenol (clove oil) as a historical and non-toxic watercolor preservative.
On Cadmium & Wastewater Impact: Scientific dossier: Significance of cadmium from artists' paints to agricultural soil and the food chain (ECHA / PubMed Central PMC5044963), detailing how brush rinsing impacts sewage sludge and agricultural soils.
Ready to start making your own?
Check out my video "Making Watercolor Medium" to watch the exact steps, and grab your natural ingredients to start building a safer, cleaner, and more eco-friendly art practice today!
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