Scent Science: Why Did My Product Change Colour?

Let's set the scene. You spent hours perfecting your latest product batch. You poured a bright-white candle, a crystal clear lotion, a pale bar of soap. Your product looked perfect on the curing rack. Then, weeks later, disaster. That pristine white or soft blue has transformed into a muddy tan, a dull yellow, or a strange green. You panic, and you blame yourself.

But take a deep breath, maker. What you're witnessing isn't your mistake, it's chemistry. Understanding the science behind fragrance colour shifts will help you troubleshoot formulations, manage your customers' expectations, and master your creative craft. Ready for a science lesson?

 CAN'T STOP THE CHEMISTRY 

We often think of pouring a candle or mixing soap as the final step in production. In reality, your product is a living chemical environment. Fragrance oils are a delicate blend of dozens of distinct aromatic compounds. These can include natural essential oils, synthetic aldehydes, esters, ketones, and alcohols. Even after blending these compounds into your wax, base, or emulsion, they don't remain static. They actively respond to catalysts in your environment. The most common of these catalysts are...

Oxygen: Exposure to air can trigger oxidation, altering chemical structures in your fragrance oil.

Light: UV rays can break chemical bonds and fade or alter pigments.

Heat: Warm storage temperatures can accelerate natural chemical reactions in your product.

Your product base: The pH of your soap, the fatty acids in your oils, and the type of wax you use can all react with fragrance compounds.

 OH VANILLIN 

lf you ask experienced makers about discolouration, they'll probably talk to you about vanillin. Vanillin is the primary chemical compound that gives vanilla beans their sweet, comforting aroma. It's used in many bakery, gourmand, amber, and floral fragrance oils.

It's also notorious for being a little temperamental. When exposed to air and light, it undergoes a predictable chemical reaction. It oxidizes, darkens, and shifts your product colour from white to tan.

It's for this reason that reputable fragrance suppliers explicitly list vanillin percentages on their product pages. This information can help you predict exactly how a specific oil might alter the look of your product. If you want snow-white products without relying on chemical stabilizers, we suggest using vanillin-free fragrances.

 HIDDEN CULPRITS 

Vanillin takes most of the blame, but it's not the only compound responsible for colour changes in your products. If you avoided vanillin and still ended up with a green, yellow, or blue-grey product, we'd point the finger at one of these culprits...

Citrus oils and limonene: Fragrances with heavy citrus notes (think lemon, bergamot, grapefruit) are packed with terpenes like limonene. These compounds quickly oxidize when exposed to light and air, causing a colour change from clear or white to yellow or dark amber.

Indole: Indole is naturally found in many floral fragrances, like jasmine, honeysuckle, and orange blossom. It can cause a product to turn, pink, deep red, or even a purplish-tan. Who doesn't love pink?

Eugenol: Found in clove, cinnamon, nutmeg, and all-spice fragrances, eugenol is highly reactive (we've all been there), and can turn your white products a deep yellow or warm tan.

Patchouli and oakmoss: Earthy, woody, and resinous fragrance oils often contain natural compounds with dark pigment. These pigments can settle or react with your product base, shifting its colour to a murky green or blue-grey.

 YOUR OPTIONS

Yay science! Now that you know why your products are changing colour, you have three options. You can prevent colour changes chemically, design around them, or embrace them.

The first option involves using vanillin stabilizers, incorporating UV inhibitors, or switching to amber or opaque packaging that protect your formulations from light.

You can lean into colour shifts and make them intentional details in marketing your product. If you know your product will turn brown, create a coffee scented product and enhance the colour change by adding coffee grounds, cocoa powder, and dark brown micas. Incorporate dyes or pigments that will mask or complement colour shifts. Don't fight it makers.

One of the best strategies: transparency. Explain on your labels, in your product descriptions, or on your social media that colour changes happen, and that they're proof of high-quality fragrance oils. Let your customers know that colour shifts don't affect a product's safety, performance, or scent and that they're part of the unique beauty of natural, handmade items.

Another tip from us: test, test, and test again. Every fragrance oil is unique. The only way to master colour shifts is to keep records and test every batch. By understanding the chemistry happening in your bottles, jars, and ceramics, you can transform an unexpected surprise into a manageable part of your creative process.

Thanks for participating in today's chemistry lesson from Team LARK. If you made it to the end, congratulations, you get an A+ from us. Now go forth and make, makers.