What is Stearamidopropyl Dimethylamine (SD)?

Stearamidopropyl Dimethylamine (often called SD) is a cationic conditioning agent used mainly in hair conditioners, hair masks, leave-in conditioners, and co-wash products.Unlike traditional quaternary conditioners, SD becomes positively charged only after being neutralized with an acid such as Lactic Acid or Citric Acid. Once activated, it attaches to the negatively charged areas of damaged hair, leaving it smoother, softer, and easier to comb.One reason many formulators love SD is because it provides excellent conditioning while giving hair a lighter feel compared to some traditional conditioning emulsifiers.

Why Do Formulators Love SD?

Stearamidopropyl Dimethylamine offers several advantages:

1. Excellent Detangling

Hair becomes much easier to comb, both when wet and dry.

2. Leaves Hair Soft

It creates a silky, smooth after-feel without excessive buildup.

3. Reduces Frizz

Conditioned hair is less prone to flyaways and frizz.

4. Improves Shine

Hair looks healthier and reflects more light.

5. Lightweight Conditioning

Unlike heavier conditioning systems, SD gives softness without making hair feel greasy.

6. Suitable for Different Hair Types

From straight hair to curly and coily textures, SD performs well across a wide range of hair types.

Recommended Usage Rate

Lightweight conditioner 2–3%

Regular conditioner 3–5%

Deep conditioner 4–6%

Hair mask 5–6%

If SD is your primary conditioning ingredient, most formulators use:3–6% SDcombined with 4–8% fatty alcohols such as Cetearyl Alcohol or Cetyl Alcohol for stability and thickness.

If you’re combining SD with ingredients like:BTMS-25, BTMS-50, Cetrimonium Chloride, you can usually reduce SD to around:1–3%because the conditioning ingredients work together.

This helps improve slip while reducing formulation costs.

How Does SD Work?

SD works a little differently from many conditioning ingredients.Instead of being permanently charged, it needs to be neutralized with an acid.

Most formulators use: Lactic Acid or Citric Acid

Once neutralized, SD becomes positively charged and deposits onto the negatively charged hair surface.This is what gives hair its soft, conditioned feel.Without proper neutralization, SD will not perform as well.

Beginner-Friendly Conditioner Formula

Steps

1. Prepare the water phase (A) by mixing (Water, Glycerin, Lactic Acid).Do not add SD yet.
2. Prepare the oil phase by mixing Cetearyl Alcohol, Oils and Butters. Heat oil and water phase.
3. When the water phase reaches about 70°C, add the Stearamidopropyl Dimethylamine and stir until it has completely melted.
4. Combine the hot oil phase with the water phase. Blend well until a smooth emulsion forms.
5. Allow the conditioner to cool while stirring occasionally. When conditioner is below 40°C, add fragrance and Euxyl PE 9010. Mix thoroughly.

SD Frequently Asked Questions

Is SD an emulsifier?

Not by itself. SD is primarily a conditioning agent. It works together with fatty alcohols such as Cetearyl Alcohol to create a stable conditioning emulsion.

Which acid should I use together with SD?

Lactic Acid is the most common choice because it is easy to work with and contributes to a hair-friendly pH. Citric Acid is another suitable option.

Is SD suitable for curly or type 4 hair?

Yes. It is widely used in products designed for curly, coily, and textured hair because it improves slip and helps reduce tangles.

Can I use SD in leave-in conditioners?

Yes. Simply reduce the usage level to create a lighter product that won’t weigh the hair down.

Common Formulation Mistakes When Working with Stearamidopropyl Dimethylamine (SD)

1. Not Neutralizing SD Properly

This is the most common mistake beginners make. SD needs to be neutralized with an acid such as Lactic Acid or Citric Acid before it can provide its conditioning benefits. If you skip this step or don’t use enough acid, the conditioner may not provide good slip, softness, or detangling. Emulsion can also separate.

Fix

Always add you acid and ensure the ph is down before adding the SD to your water phase.

Using Too Little Cetearyl /Cetyl Alcohol

SD works best together with fatty alcohols like Cetearyl Alcohol. Using too little fatty alcohol can result in: thin conditioners, poor stability or reduced conditioning performance.

Fix

Use about 4–6% Cetearyl Alcohol when SD is your main conditioning ingredient.

Not Heating Both Phases Properly

If the oil and water phases are at significantly different temperatures, the emulsion may become unstable.

Fix

Heat both phases to approximately the same temperature (around 70–75°C) before combining them.

Tips for Better Results

• Use distilled or deionized water for better product stability.
• Blend thoroughly to create a smooth, creamy emulsion.
• Check and adjust the final pH before packaging.
• Allow the conditioner to mature for 24 hours before evaluating its final thickness.
• Record every batch so you can easily improve future formulations.

If you have been a long-time follower of my Instagram page @formulatorgh_shop, you may have noticed multiple iterations of the EMULSIFIED Hair Butter/curl cream. The effectiveness of the curling aspect depends on your hair texture. For those with extra coarse hair, it provides deep moisture for days. Conversely, for those with lighter, curlier hair, it aids in defining the curls – although it’s important to note that it doesn’t offer a strong hold.

Today, I’ve decided to create a revamped version of the Marshmallow and Oat emulsified hair butter. This time, I’m experimenting with the same or a similar formula, but incorporating different emulsifiers.

Version 1

Th Varisoft Emulsified Hair Butter: made with a blend of Varisoft eq 65, Cetearyl Alcohol, Isoamly laurate, Cocoa Butter, Mashmallow root extract, Hydrolyzed Oat Protein, Cationic guar, D-Panthenol and few more add on.

This is a version I have done quiet a few time mostly changing only the oils or butter all else stays pretty much the same.

Final result was as expected, smooth, light weight, moisturizing and detangling with just the right amout of moisture to last a few days without the need to reapply any other product.

Version 2

Btms MCC Emulsified Hair Butter.

I have tried BTMS MCC a few times before this, so I know from experience that it does not create a super thick emulsion like your regular BTMS 50 or BTMS 25 would. However, since the hair butter is expected to have a thick consistency, my goal was to determine how thick a consistency I could achieve with BTMS MCC.

I had come across a sample formulation online that used 1% HEC in conjunction with BTMS MCC (2%) and cetearyl alcohol (5%). I decided to try that formulation and observe the results.

Everything else in this formulation is the same as the Varisoft version, except I replaced Varisoft with BTMS MCC, increased the cetearyl alcohol amount, and added HEC.

The final result looked and felt more compact ( due to the added gum and higher cetearyl alcohol content, I believe). The performance went beyond what I had expected. I must say that this is my current favorite. It defined the hair much more effectively than version 1 did. The section where I used this butter had far fewer tangles than all the others when I was unraveling my twists after 3 weeks.

Version 3

Btms 25 Emulsified Hair Butter

At this point, I was curious about how the performance of this would be if I switch the mashmallow root extract for cucumber extract and go with regular guar gum in place of HEC in Version 2.

Let’s just say this was my least favourite of all three.

Some Lessons and Observations made

1. Some changes might appear minor, but they have the potential to entirely transform the appearance and texture of your formulation. For instance, making adjustments to emulsifiers can significantly impact the look and tactile experience of your product.
2. Different gums have different textures. The verison with HEC feels different from the one with guar or the one with no added gum.