Improving Serum Absorption and Texture: Resolving Sticky Rainbow Film and Foaming Issues

Based on your formulation and the issues described (shiny/rainbow appearance, poor absorption, and foaming), here is an analysis and suggested adjustments:

1. The "Rainbow" and "Crinkly" Appearance

The shiny, rainbow-like (iridescent) film and the "crinkly" sensation are likely caused by the high concentration of WaterSil™ 8/12 (3%) combined with AnyGel™ (0.6%).

• WaterSil™ 8/12 is a blend of water-soluble silicones. While excellent for detackifying, at the maximum usage rate (3%), it can form a very thin, continuous film on the skin. This film can cause light interference (the rainbow effect) and may feel "strange" or "crinkly" as it sets if the polymer network from the AnyGel™ is also quite rigid.
• Recommendation: Reduce WaterSil™ to 1.0–1.5%. This is usually sufficient for detackification without creating a heavy film.

2. Switching to WaterSoft™

Switching or blending with WaterSoft™ is an excellent idea.

• WaterSoft™ (PEG/PPG-17/6 copolymer) provides a silky, soft skin feel without the "filmy" characteristic of silicones. It is also completely water-soluble and helps with the "absorption" feel by making the water phase feel wetter and more lubricious.
• Suggested Change: Use 1.0% WaterSil™ and 2.0% WaterSoft™. This will likely resolve the smell issue and improve the visual finish on the skin.

3. Adding Carbomer U21 and the Foaming Issue

The slight foaming during application is a common trait of natural gums like AnyGel™ (Dehydroxanthan Gum) when they are rubbed into the skin.

• Carbomer U21 is highly recommended here. It acts as a defoamer in gel systems. Adding just 0.1% to 0.2% will significantly reduce the foaming and improve the "break" of the gel, making it feel like it "melts" into the skin faster rather than sitting on top.
• Note: Carbomer U21 requires neutralization (e.g., with Triethanolamine or AMP) to reach pH 5.5–7.0 to thicken properly.

4. X-Glycerin (Polyglycerin-10)

At 3.0%, X-Glycerin is within a good range, but since you have many other humectants (Betaine, Propanediol, Panthenol), the formula might be "over-hydrated," leading to the slow absorption.

• Recommendation: Try lowering X-Glycerin to 1.5–2.0% to see if the "heaviness" subsides.

5. Increasing SNAP-8

You can safely increase SNAP-8 (Acetyl Octapeptide-3).

• The recommended usage rate is 3% to 10%. Increasing it to 8% or 10% will enhance the anti-wrinkle efficacy.
• Since SNAP-8 is water-based, it will not negatively impact the texture or the "rainbow" issue; in fact, increasing the active water-phase components while decreasing the film-formers (WaterSil) will likely help the serum feel more "active" and less "filmy."

Suggested Formula Adjustments:

• WaterSil™ 8/12: Reduce to 1.0%
• WaterSoft™: Add 2.0%
• Carbomer U21: Add 0.1% (and ensure pH is adjusted to ~6.0)
• X-Glycerin: Reduce to 1.5%
• SNAP-8: Increase to 8.0% (adjust water q.s.)

These changes should result in a serum that absorbs quickly, has a matte/natural finish, and does not foam during application.