How to Adjust the Viscosity of Lotions, Creams, and Conditioners

Why adjust viscosity?

Viscosity (thickness) is one of the main differences between a fluid lotion, a richer cream, and a dense conditioner. It affects how a product pumps, spreads, and feels on skin or hair, so being able to systematically thicken or thin an existing base is useful in both R&D and small production tweaks.

If you'd like some guidance on how to fix the viscosity of a body wash or shampoo, check out these instructions.

Or for more on natural thickeners, check out this blog.

Thickening lotions, creams, and conditioners with Xanthan Gum

For finished emulsions that are a bit too thin but otherwise stable, one of the simplest lab‑friendly approaches is to use Xanthan Gum as a rheology modifier.

Typical usage considerations:

• In emulsions, Xanthan Gum is usually used around 0.1–0.5% of the total formula; higher levels can lead to a very gel‑like or stringy texture.
  
• When formulating from scratch, xanthan is normally dispersed into the water phase before emulsification. For existing bases, it can be post‑added carefully as described below.
  

Step‑by‑step method for post‑thickening with Xanthan Gum:

1. Weigh and record the amount of Xanthan Gum you plan to use as a starting estimate.
2. Weigh your lotion, cream, or conditioner and record the weight.
   
3. Begin mixing the product with suitable shear (for example, a stick blender or overhead mixer).
   
4. While mixing, slowly sprinkle in the Xanthan Gum, allowing it to hydrate and distribute before adding more.
   
5. Continue until you reach the desired viscosity, then stop mixing.
   
6. Weigh the remaining Xanthan Gum; subtract this from your starting amount to determine how much you actually added.
   
7. Calculate the Xanthan Gum percentage relative to the total product weight. This becomes your working usage level for this specific base, and you can incorporate that percentage into your formula if you are reformulating from scratch.
   

After any significant adjustment, check the product for signs of instability (for example, separation, excessive aeration, or undesirable stringiness) over time.

Still feeling a little unsure? Follow along with our video tutorial here!

Thinning lotions, creams, and conditioners with water or distillates

If a lotion, cream, or conditioner is too thick, the usual approach is to add more aqueous phase, such as either preserved deionized water or a suitably preserved distillate/hydrosol, all while maintaining an effective preservation system.

Key points before thinning:

Adding water or distillate dilutes the original preservative system; the finished formula must still be adequately preserved. We love utilizing our Cucumber Distillate for this purpose.

Many cosmetic distillates are supplied with their own preservative, but the overall product still needs to be evaluated as a whole.

If you are using deionized water, it should be preserved before addition or added in a way that you can calculate the final preservative level in the complete formula. Phenoxyethanol is commonly used up to a maximum of 1% in finished cosmetic products, often supported by a chelator such as Tetrasodium Glutamate Diacetate (GLDA) at around 0.1–0.5% as a booster.

Example approach for pre‑preserving added water:

• Prepare a preserved water phase using a Phenoxyethanol‑based system plus GLDA, keeping in mind that the final Phenoxyethanol level in the finished product should not exceed 1%, and GLDA is typically used around 0.1–0.5%.
  

Step‑by‑step method for thinning with preserved water or distillate:

• Weigh and record the amount of preserved deionized water or preserved distillate you expect to need.
  
• Weigh your lotion, cream, or conditioner and record the weight.
  
• Begin mixing the product with gentle to moderate shear.
  
• Slowly add the preserved water or distillate while mixing until the desired viscosity is reached.
  
• Weigh what remains of your water or distillate and subtract from the original amount to see how much was actually added.
  
• Calculate the percentage of water or distillate relative to the total product weight.
  
• Use this percentage as your reference if you need to repeat the adjustment on the same base, and integrate it into your formula if you are reformulating at the development stage.
  

Any time you significantly change the water phase, plan to re‑evaluate the finished product’s microbiological and stability profile, especially if the product is intended for market.

Final checks and best practices

When you adjust viscosity on an existing base:

• Document all weights and percentages so that successful adjustments can be reproduced at scale.
  
• Recheck pH, viscosity, and appearance over time; thickening and thinning can subtly influence emulsion stability and sensorial properties.
  
• For commercial products, confirm that the adjusted formula still meets your internal preservation, stability, and performance standards, and consider challenge testing if the water phase has changed meaningfully.
  

Check out our great stock creams, lotions, and conditioners! The options are limitless when you customize one of our stock products. Plus, we love knowing how you alter and customize our bases to suit your brand! Please don’t hesitate to share your story with us or reach out with any questions.