Gel Cream Liquefies After Adding Plant Extract

Based on the ingredients and the problem you described, the most likely reason your gel cream became liquid after adding the Wakame Extract is an incompatibility between the extract and the gelling agent, Carbopol 940.

Here's a breakdown of why this happens and how to fix it:

Why it happened:

1. Carbopol 940 is pH-Sensitive: Carbopol polymers thicken by forming a gel network when they are neutralized to a slightly alkaline pH (typically pH 5.5 to 8.5) using a base like TEA (Triethanolamine). In your formula, TEA is used to neutralize the Carbopol and create the gel base.
2. API (Wakame Extract) Likely Lowered the pH or Contains Electrolytes: Many natural extracts, including plant extracts, can be acidic or contain salts (electrolytes).
   • If the Wakame Extract is acidic, adding it would lower the overall pH of your gel base. If the pH drops below the effective range for Carbopol (especially below pH 5.0), the gel structure collapses, and the mixture becomes liquid again.
   • Even if the pH doesn't drop significantly, high concentrations of electrolytes (salts) in the extract can also disrupt the Carbopol gel network, causing a loss of viscosity.

How to fix it:

The primary solution is to adjust the pH after adding the API.

1. Check the pH: Before adding the Wakame Extract, measure the pH of your gel base. Then, after adding the extract and observing the liquefaction, measure the pH again. You will likely see a significant drop in pH.
2. Add More TEA: Slowly add more TEA (Triethanolamine) drop by drop to the mixture after you have added the Wakame Extract. Stir well and check the viscosity as you add the TEA. Continue adding until the desired gel cream consistency returns. Be careful not to add too much, as excessively high pH can also cause issues. Aim for a final pH in the range of 5.5 to 6.5, which is generally suitable for skin products and within Carbopol's effective range.

Which ingredients are incompatible?

It's not necessarily that specific ingredients are "incompatible" in a harmful way, but rather that the chemical properties of the API (Wakame Extract - likely its pH or electrolyte content) interfere with the function of the gelling agent (Carbopol 940). The emulsifier system (Polysorbate 80, Span 80, Squalane) might also be affected by significant pH changes, but the primary cause of the sudden liquefaction is almost certainly the breakdown of the Carbopol gel.

Should you adjust proportions or change ingredients?

• Adjusting Proportions: The most direct adjustment is adding more TEA to counteract the effect of the API on the Carbopol. You might also consider slightly increasing the initial Carbopol concentration in your base if the API consistently causes a significant viscosity drop that is hard to recover with pH adjustment alone, but pH adjustment is the first and most important step.
• Changing Ingredients: If the Wakame Extract is highly problematic (e.g., very acidic or very high in electrolytes) and pH adjustment is difficult or results in an undesirable texture, you could consider using a different gelling agent that is more tolerant to pH variations and electrolytes, such as Acrylates/C10-30 Alkyl Acrylate Crosspolymer or certain types of modified cellulose gums or natural gums (like Xanthan Gum, though it has a different feel). However, try adjusting the pH first, as it's the simplest solution with your current formula.

In summary, the liquefaction is most likely due to the Wakame Extract lowering the pH or introducing electrolytes that disrupt the Carbopol gel. The solution is to adjust the pH back up using TEA after adding the extract.