How to use Laurylamidopropyl Dimethylamine Oxide(LAPO)

Using Laurylamidopropyl Dimethylamine Oxide (LAPO) effectively requires understanding its properties and how it interacts with other ingredients.

Here is a comprehensive guide on how to use LAPO, from basic handling to formulation tips.

1. Key Properties to Remember Before Use

Form: Typically supplied as a viscous liquid or gel (e.g., 30-35% active matter).

pH Behavior: It is amphoteric. It acts as a nonionic surfactant at neutral to alkaline pH (≥7) and develops a mild cationic charge in acidic conditions (<7). This is crucial for its conditioning and thickening effects.

High Compatibility: It is compatible with most surfactants (anionic, nonionic, amphoteric) and salts.

Primary Functions: Thickening, foam boosting/stabilizing, and conditioning.

2. Handling and Storage

Storage: Store in a cool, dry place. Keep the container tightly sealed to prevent contamination and moisture loss.

Handling: Use personal protective equipment (PPE) such as gloves and safety goggles. While considered mild, the concentrate can be irritating.

3. How to Incorporate LAPO into Formulations (Step-by-Step)

LAPO is almost always added during the water phase of manufacturing. The standard method is the "Post-Add" technique.

Standard Post-Add Method:

This is the most common and effective way to leverage LAPO's thickening power.

Create the Base Surfactant System:

In your main vessel, charge deionized water.

Add your primary surfactants (e.g., Sodium Lauryl Sulfate (SLS), Sodium Laureth Sulfate (SLES), Cocamidopropyl Betaine). Ensure they are well-dissolved and mixed.

Adjust pH (If Necessary):

At this stage, you can adjust the pH of your base mixture. Remember, LAPO will thicken best in a slightly acidic to neutral pH range (5.0-7.0). If your final product is meant to be in this range, you can adjust it now.

Dilute and Add LAPO:

Do not add LAPO concentrate directly to the main batch. It will form stubborn, fish-eye-like lumps that are very difficult to dissolve.

Correct Method: In a separate beaker, pre-dilute the required amount of LAPO concentrate with an equal part or more of warm water (30-40°C / 85-105°F). Stir until it forms a clear, homogeneous, low-viscosity solution.

Slow Addition: While your main batch is under moderate agitation, slowly trickle or pour the pre-diluted LAPO solution into the batch.

Final Thickening and pH Adjustment:

After the diluted LAPO is fully incorporated, you will observe the viscosity of the entire batch increasing. Allow it to mix for 10-20 minutes to reach its maximum viscosity.

Now, make your final, precise pH adjustment. Adding acid (e.g., Citric Acid) will further increase viscosity due to LAPO's cationic behavior. Adding base (e.g., Sodium Hydroxide) will reduce viscosity.

Add preservatives, fragrances, and other heat-sensitive ingredients at the end, under light mixing.

4. Typical Usage Levels

As a Foam Booster/Stabilizer: 1 - 3%

As a Viscosity Modifier/Thickener: 2 - 5%

As a Conditioning Agent: 1 - 4%

Note: These are general ranges. Always refer to your supplier's specifications and perform lab tests.

5. Example: Simple Shampoo Formulation

This illustrates how LAPO fits into a typical recipe.

Ingredient Function % Weight

Phase A: Water

Deionized Water Solvent q.s. to 100%

Phase B: Surfactants

Sodium Laureth Sulfate (SLES) Primary Surfactant 10.0%

Cocamidopropyl Betaine Secondary Surfactant/Foam Booster 5.0%

Phase C: Thickener & Conditioner

Laurylamidopropyl Dimethylamine Oxide (LAPO) Thickener, Foam Stabilizer, Conditioner 4.0%

Phase D: Finishing

Citric Acid (50% Solution) pH Adjuster To pH 5.5-6.0

Preservative Prevents Microbial Growth q.s.

Fragrance, Color Aesthetics q.s.

Manufacturing Instructions:

Phase A & B: Add Water to the main tank. With agitation, add SLES and Cocamidopropyl Betaine. Mix until clear and uniform.

Pre-Mix Phase C: In a separate beaker, pre-dilute the 4.0% LAPO with 8% warm water (a 1:2 ratio). Stir until clear.

Add Phase C: Slowly add the pre-diluted LAPO to the main tank with moderate agitation. Mix for 15-20 minutes. Observe the viscosity increase.

Phase D: Use Citric Acid to adjust the pH to 5.5-6.0. This will likely cause a final slight increase in viscosity.

Add Preservative and Fragrance. Mix gently to avoid air entrapment.

QC Check: Final check of pH, viscosity, and appearance.

Key Troubleshooting Tips

Problem: Lumps/Gel Balls Formation.

Cause: Adding concentrated LAPO directly.

Solution: Always pre-dilute with warm water as described above.

Problem: Not Thickening Enough.

Causes & Solutions:

pH is too high: Lower the pH to the acidic range (5.0-6.5) using Citric Acid.

Not enough salt or primary surfactant: LAPO's thickening is synergistic. Ensure your base surfactant system is properly formulated. You can add a small amount of Sodium Chloride (table salt) to further boost viscosity.

Insufficient mixing time: After adding LAPO, allow enough time (15-20 mins) for viscosity to build.

Problem: Over-Thickening.

Cause: pH is too low, or too much LAPO/salt was used.

Solution: Slightly raise the pH with a mild base (e.g., Sodium Hydroxide solution). Alternatively, dilute the batch with a small amount of water.

By following these guidelines, you can effectively harness the thickening, foaming, and conditioning benefits of LAPO in your personal care and cleaning formulations.