Solutions for White Residue

• Increase Humectants: Adding more humectants like Glycerin, Propanediol, or Butylene Glycol to your formulation can help keep the ingredients hydrated on the skin for longer, reducing the chance of them precipitating and leaving a residue as the water evaporates.
• Improve Dispersion: Ensure the Hydrogenated Lecithin and other powders are very finely and evenly dispersed in the water phase. While Hydrogenated Lecithin is typically dispersed in oil, ensuring thorough mixing in your water-based system is crucial. You might consider using a high-shear mixer if available.
• Consider a Dispersant/Solubilizer: Although Hydrogenated Lecithin is not water-soluble, a suitable dispersant or co-solubilizer compatible with both the water phase and the lecithin's nature might help keep it suspended more effectively. However, finding the right one might require experimentation.
• Adjust Concentration: The total concentration of solid ingredients (3% Hydrogenated Lecithin, 5% Niacinamide, 4% N-Acetyl Glucosamine) is quite high at 12%. If the above methods don't fully resolve the issue, you might consider slightly reducing the concentration of one or more of these ingredients to see if it reduces the residue while still providing desired benefits.
• Alternative Form of Phospholipid: While you are using Hydrogenated Lecithin powder, other forms of Lecithin or Phosphatidylcholine might be available that are easier to incorporate into water-based formulas without residue, although they may have different properties or intended uses.

Experimenting with increasing humectants or improving dispersion are good starting points to address the residue issue with your current formulation.