Titanium Dioxide in Cold Process Soap: Complete Guide to Usage, Glycerin Rivers, and Vanillin Discoloration

Titanium Dioxide in Cold Process Soap: A Guide from Di at Wixy Soap

Let's explore one of the most useful ingredients in soap making: titanium dioxide. As someone who has been crafting soaps for years, I find titanium dioxide invaluable for achieving brighter, more opaque bars. In this guide, I'll share my information based on reliable practices, including insights drawn from experts like Anne Marie at Bramble Berry. At Wixy Soap, we stock both oil-dispersible and water-dispersible varieties to suit different preferences. We'll cover what it is, how to use it in cold process soap, tips for avoiding glycerin rivers, and more. I'll also touch on personal preferences for white soaps and considerations for fragrances containing vanillin. Let's get started.

Understanding Titanium Dioxide

Titanium dioxide, often abbreviated as TD, is a naturally occurring mineral oxide (TiO₂) that is refined into a fine white powder. Its primary function in cosmetics and soap is as a whitening agent and opacifier, thanks to its excellent light-scattering properties. This makes it ideal for brightening soap bases, counteracting yellowing from oils, or creating a clean canvas for color designs.

There are two main types relevant to soap makers: oil-dispersible and water-dispersible. The oil-dispersible version is hydrophobic and mixes best with oils, forming a smooth paste that incorporates evenly into soap batter. The water-dispersible type has a coating that allows it to blend readily with water or lye solutions, which can be convenient for certain techniques.

At Wixy Soap, we offer both because each has its advantages. Oil-dispersible TD provides more control and is less likely to contribute to issues such as glycerin rivers when used properly. Water-dispersible is quicker to prepare in some cases. Both are cosmetic-grade, safe for skin contact (including eyes and lips in appropriate formulations), and stable in cold process soap. Always handle the dry powder with care—use a mask to avoid inhalation—and perform patch tests for new formulations.

Titanium dioxide has been used as a pigment for decades and is approved for cosmetic use. While derived from natural sources, the refined product is not considered organic. Responsible sourcing ensures minimal environmental impact.

How to Use Titanium Dioxide in Cold Process Soap

Cold process soap making allows for full customization, and titanium dioxide integrates well when handled correctly. The key is proper dispersion to avoid clumps or uneven distribution.

For oil-dispersible TD, the standard approach is to mix 1 teaspoon of powder with 1 tablespoon of a lightweight oil, such as sweet almond or sunflower. Use a mini mixer or frother to create a lump-free slurry. This prevents speckling in the final bars. Optionally, micronizing the powder in a coffee grinder beforehand can further reduce clumps.

For water-dispersible TD, follow a similar ratio but use distilled water instead. Stir thoroughly until smooth.

Add the dispersed TD to your batter at light to medium trace, when the mixture has emulsified and begun to thicken slightly. Start with 1-2 teaspoons of dispersed mixture per pound of oils for moderate whitening, increasing to 3-4 teaspoons for a brighter white. Incorporate gradually with a stick blender or whisk, monitoring for acceleration of trace—TD can thicken batter quickly.

Work at cooler temperatures, around 100-110°F for both oils and lye solution, to maintain fluidity. If your fragrance accelerates trace, add TD earlier.

Example basic recipe for a 2-pound batch:

- Oils: 10 oz coconut, 10 oz olive, 6 oz palm, 4 oz shea butter, 2 oz castor.

- Lye: Calculated for 5-6% superfat, using distilled water.

- TD: 2-4 teaspoons dispersed in oil.

- Fragrance: As desired.

Combine lye and oils at matching temperatures, blend to trace, add dispersed TD and fragrance, pour into mold, and cure for 4-6 weeks.

Always use a lye calculator for safety and test small batches.

Benefits and Considerations

Titanium dioxide excels at whitening and opacifying, masking natural yellow tones from oils or essential oils. It creates opaque bars suitable for layers, embeds, or vibrant color contrasts when paired with micas. It remains stable over time, unlike some colorants that fade.

However, higher amounts can thicken trace rapidly, requiring quick work. Poor dispersion leads to streaks, and excess may slightly dry the soap feel—balance with moisturizing oils.

A Personal Note on White Soaps

Some soap makers prefer consistently white bars for their clean, classic appearance. It allows the fragrance to take center stage and gives a professional, uniform look that appeals to many customers.

For me, it varies depending on my mood and the project. On days when I'm seeking simplicity or purity, I use more TD for bright white bars—perhaps with a fresh, unscented or lightly scented formula. Other times, especially with fragrances low in vanillin, I use less or none, allowing the natural creamy tone of the oils to show through for a softer, more organic feel.

Fragrance plays a big role here. Vanillin, a compound in many vanilla-based or warm scents, causes browning over time as the soap cures. In those cases, I often add TD to lighten the effect, resulting in a pale beige rather than a deep tan. For high-vanillin fragrances, I might embrace the discoloration intentionally, designing around warmer tones. Checking fragrance descriptions for vanillin content helps plan accordingly—low or none means more flexibility with natural colours.

Glycerin Rivers: Causes and Prevention

One common issue with TD is glycerin rivers—translucent or cracked veins in the soap caused by glycerin (a natural saponification byproduct) separating during overheating in gel phase. These are more prominent with dense pigments like TD, as the particles highlight the separation. Rivers are cosmetic only; the soap remains safe and functional.

Overheating triggers them, often from high temperatures, full water amounts, insulating molds, or accelerating fragrances.

Prevention strategies, informed by established soap-making practices:

- Disperse TD in oil rather than water to reduce moisture that promotes separation.

- Use a water discount of 10-20% (reduce distilled water in the recipe) to lower overall liquid and heat buildup.

- Soap at lower temperatures (90-110°F) and avoid insulating; consider room-temperature soaping.

- Place the mold in the freezer for 24 hours to prevent gel phase entirely.

- Mix colorants thoroughly and add incrementally.

If rivers occur, they can add an interesting textured look—some designs even feature them intentionally for an artisanal effect.

Additional Tips and Variations

For pastel shades, combine TD with micas in divided batter. In vanillin-heavy recipes, extra TD mitigates browning but may require more prevention against rivers.

Troubleshooting: Speckles indicate poor dispersion—micronize or mix longer. Excessive thickening? Reduce TD amount or work cooler.

Safety reminders: Wear protective gear when handling lye and powders. TD is non-toxic in finished soap, but avoid inhaling dust.

While focused on cold process, TD works in melt-and-pour (disperse in alcohol) but settles in lotions.

Final Thoughts

Titanium dioxide is a versatile tool for enhancing cold process soaps, offering whitening and opacity with proper use. Whether aiming for bright white bars or adjusting for fragrance effects like vanillin browning, it provides reliable results when combined with good techniques, such as oil dispersion and temperature control to minimize glycerin rivers.

At Wixy Soap, our selection of both types ensures you have options for your recipes. Experiment thoughtfully, and enjoy the process—it's rewarding to create bars that reflect your style.

Thanks for reading. Feel free to share your experiences with Titanium Dioxide in the comments.