Choosing a Thickener for Nano Colloidal Silver Serum

Question

I made the solution and all good but if I wanted to turn this into a more substantial serum to make it thicker what thickener do you suggest I could use?

I have a number of thickeners in my stock including:

Sepimax Zen
Xanthan Gum
Xanthan Gum Clear
Polyacrylamide and C13-14 Isoparaffin and Laureth-7
Aristoflex AVC
Acacia Gum
Guar Gum
and probably a few more.

Can you please help me with this and also advise on approx % of thickener to use for small test - I am only making this for home use and not to sell.

My current formula:

Distilled Water
Nano Colloidal Silver 2000ppm solution
Glycerin
Panthenol Vit B5
Pentylene Glycol
Liquid Germall Plus preservative

Many thanks in advance.

Answer 1

To turn your solution into a more substantial serum, you have several excellent options from your current stock. Since your formula contains Nano Silver (2000ppm, Colloidal, Yellow Solution), the primary constraint is avoiding electrolytes (salts) and cationic (positively charged) ingredients to maintain the stability of the silver particles.

Based on your ingredients (Distilled Water, Glycerin, Panthenol, Pentylene Glycol, and Liquid Germall Plus), your solution is currently non-ionic and low-electrolyte, which gives you good flexibility.

Recommended Thickeners from Your Stock

Sepimax Zen (Polyacrylate Crosspolymer-6)
- Best for: A professional, elegant "serum" feel with high clarity.
- Why: It is an anionic polymer that is extremely robust. Even though your current formula is low-electrolyte, Sepimax Zen is famous for its ability to handle challenging ingredients. It creates a beautiful, non-sticky gel.
- Test Usage: 0.5% to 1.0%. Start with 0.5% for a fluid serum; 1.0% will give a thicker, more substantial gel.
- Mixing: Sprinkle onto the water surface and allow it to hydrate, or use high-speed mixing.
Xanthan Gum (Clear Gel Type)
- Best for: A natural, very stable, and cost-effective option.
- Why: It is highly compatible with almost all ingredients and pH levels. The "Clear" version will ensure your serum remains transparent (though it will still be yellow due to the Nano Silver).
- Test Usage: 0.5% to 0.8%. Over 1% can sometimes feel a bit "slimy" or "stringy."
- Mixing: Pre-mix the Xanthan Gum with your Glycerin first to create a slurry. This prevents "fish-eyes" (clumps) when you add it to the water.
Aristoflex AVC
- Best for: A very fresh, quick-breaking skin feel.
- Why: It creates beautiful clear gels.
- Caution: It is extremely sensitive to electrolytes. While your current list looks safe, if you ever add botanical extracts or certain actives (like Sodium PCA or Aloe), the gel will instantly turn back into water.
- Test Usage: 0.5% to 1.0%.
Easy Cream Maker™ (Polyacrylamide & C13-14 Isoparaffin & Laureth-7)
- Best for: If you want a "milky" serum or a light lotion texture.
- Why: This is a pre-neutralized polymer that works instantly. It will turn your clear yellow solution into an opaque, creamy yellow lotion.
- Test Usage: 1.0% to 2.0%.

Suggested Small Test Batch (50g)

If you want to test Sepimax Zen at 1%:

Distilled Water: 42.5g (85%)
Glycerin: 1.5g (3%)
Panthenol (Vitamin B5): 1.0g (2%)
Pentylene Glycol: 1.5g (3%)
Nano Silver (2000ppm): 2.5g (5%) — Note: The product recommends 1-5% for disinfection.
Sepimax Zen: 0.5g (1%)
Liquid Germall Plus: 0.5g (1%) — Adjust based on your specific preservative's recommended rate.

Important Tips for Nano Silver Stability:

Avoid Salt: Do not add any salt or ingredients containing electrolytes (like Sodium Hyaluronate or certain extracts), as they can cause the silver to precipitate.
pH Range: Keep the final pH between 6.0 and 8.0 for the best stability of the colloidal silver.
Light Protection: Since silver is light-sensitive, store your finished serum in an opaque or dark amber bottle.