A major regulatory shift is coming to the European cosmetics market—and it’s time to act.

Starting June 6, 2027, the European Union will enforce a new restriction on Cyclopentasiloxane (D5), limiting its concentration in leave-on cosmetic products to 0.1%. This change, part of REACH Annex XVII, is designed to reduce the environmental impact of volatile cyclic silicones. While the goal is sustainability, the impact on formulation is significant—especially for hair serums and oils that have long relied on D5 for its lightweight texture, smooth glide, and shine-enhancing properties.

For formulators and brands, this presents a clear challenge: How do you adapt your hero products to meet new regulations—without sacrificing the performance your consumers love?

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High-Performance Alternatives

At Momentive, we understand that performance is non-negotiable. That’s why we’ve developed Harmonie™ Soft fluid and Harmonie™ GB-2301 blend—two innovative ingredients that offer a compliant, sensory-rich alternative to D5.

These ingredients are:

• 100% D5-free and compliant with upcoming EU regulations
• Offer a high natural origin index
• Designed to deliver shine, frizz control, and heat protection
• Lightweight and volatile
• Suitable for a wide range of hair types and textures
• An ideal replacement to existing formulations

Whether you’re reformulating a best-seller or developing a new product line, these solutions help you stay ahead of regulatory changes while maintaining the luxurious feel and performance your customers expect.

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Formulating leave on hair treatments with D5 alternatives

Harmonie Soft fluid and Harmonie GB-2301 blend can be used to either replace the cyclic silicones in existing formulas or developing entirely new ones.  These volatile D5 alternatives are lightweight enough for use in hair leave-on hair treatments, and can be used individually or in combination. It is possible to use as much as 60%  C9-12 Alkane in the final formulation.

Their performance has been validated through various formulation prototypes, demonstrating consistent efficacy and adaptability across a range of viscosity and sensory profiles

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Why It Matters

Consumers are increasingly aware of ingredient safety and environmental impact. Brands that act early to reformulate with sustainable, compliant alternatives will not only avoid regulatory disruption—they will also strengthen consumer trust and brand equity.

With over 80 years of expertise in cosmetic science, Momentive is your trusted partner in navigating change. Our ingredients are already used by some of the world’s leading beauty brands.

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