First, we attempted to verify the efficacy of SESAMULS© OW in a system made of a lipidic phase of different natures and of a large water phase. In all the emulsions made during this experiment, the emulsifier was used incorrectly in order to render critical the stability of the various systems.

A larger dose would have facilitated the formation of a more stable emulsion with superior organoleptic properties, but would have made the search for the most balanced emulsifying system more difficult.

The basic formulae used for the experiments are as follows:

   Oily phase (total) 5 10
   Aqua 91 86
   SESAMULS© OW 2 2
   Diglycerin 2 2
  1st Series internal phase Stability
   1 Hydrogenated Poly-1 Decene 2,5%, Octyl Palmitate 2,5% NN
   2 Hydrogenated Poly-1 Decene 2,5%, Octyl Stearate 2,5% NN
   3 Hydrogenated Poly-1 Decene 2,5%, Octyldodecyl Lactate 2,5% NN
   4 Hydrogenated Poly-1 Decene 2,5%, Isopropyl Myristate 2,5% NN
   5 SILGREEN© C 2,5%, Octyl Palmitate 2,5% S
   6 Hydrogenated Poly-1 Decene 5%, Octyl Palmitate 5% N
   7 Hydrogenated Poly-1 Decene 5%, Octyl Stearate 5% NN
   8 Hydrogenated Poly-1 Decene 5%, Octyldodecyl Lactate 5% NN
   9 Hydrogenated Poly-1 Decene 5%, Isopropyl Myristate 5% NN
   10 SILGREEN© C 5%, Octyl Palmitate 5% S
   11 Octyl Palmitate 5% N
   12 Octyl Stearate 5% N
   13 Hydrogenated Poly-1 Decene 5% NN
   14 SILGREEN© C 5% N
   15 Octyldodecyl Lactate 5% N
   16 Cannabis Sativa (Oil) 1%, Olea Europaea (Unsaponifiables) 1%, Buxus Chinensis (Oil) 1%, Butyrospermum Parkii 2% N

S =stable emulsion – N = unstable emulsion – NN = separation within 24 hrs

The most evident inconvenience of these emulsions is the separation (creaming) of part of the water phase, which occurs after exposure 40°C temperatures. In these applications and when used alone, in very low percentages, SESAMULS© OW shows limited efficacy.

From the analysis of the first series of emulsions, it emerges that the presence of an ester product like Octyl Palmitate improves the polarity of the oil phase and moderates the non-polarity of the hydrocarbon derivatives improving the stability of the emulsion itself.

To improve the emulsifying ability it is necessary to introduce a component that is able to stiffen the structure of the interfacial film.

Let’s prepare a second series of emulsions based on the combination of SESAMULS© OW + Stearic Acid. Obviously, the conditions, method of preparation and components of the various formulations remain the same as the previous experiment.

SESAMULS© OW 2
Stearic Acid (vegetal source) 2
  2nd Series internal phase Stability
   1 Hydrogenated Poly-1 Decene 2.5%, Octyl Palmitate 2.5% S
   2 Hydrogenated Poly-1 Decene 2.5%, Octyl Stearate 2.5% NN
   3 Hydrogenated Poly-1 Decene 2.5%, Octyldodecyl Lactate 2.5% S
   4 Hydrogenated Poly-1 Decene 2.5%, Isopropyl Myristate 2.5% NN
   5 SILGREEN© C 2.5%, Octyl Palmitate 2.5% S
   6 Hydrogenated Poly-1 Decene 5%, Octyl Palmitate 5% S
   7 Hydrogenated Poly-1 Decene 5%, Octyl Stearate 5% NN
   8 Hydrogenated Poly-1 Decene 5%, Octyldodecyl Lactate 5% NN
   9 Hydrogenated Poly-1 Decene 5%, Isopropyl Myristate 5% N
   10 SILGREEN© C 5%, Octyl Palmitate 5% S
   11 Octyl Palmitate 5% S
   12 Octyl Stearate 5% S
   13 Hydrogenated Poly-1 Decene 5% N
   14 SILGREEN© C 5% N
   15 Octyldodecyl Lactate 5% S
   16 Cannabis Sativa (Oil) 1%, Olea Europaea (Unsaponifiables) 1%, Buxus Chinensis (Oil) 1%, Butyrospermum Parkii 2% S

The molecules of stearic acid, shorter than those of the emulsifier, make the system more stable. The organoleptic characteristics of the emulsion are also improved; it appears more shiny and compact and it spreads more evenly and easily. Let’s try to further improve the stability of the emulsion by adding Cetearyl Alcohol.

   SESAMULS© OW 2
   Stearic Acid 1
   Cetearyl Alcohol 1

In this third series of emulsions, no substantial improvement is noticeable over the second. Moreover, in some cases, the stability is worse and the organoleptic characteristics suffer. In view of these results, we shall continue the experiment using the combination of SESAMULS© OW + Stearic Acid.

In the course of the realization of the described emulsions, during the emulsification phase, the fatty phase incorporated the water phase quickly and easily without forming lumps or non-dispersible clumps. A further passage through the turbo mixer created a shiny, homogenous emulsion of cosmetic grade quality every time.

Due to these results, we decided to perfect a base of absorption capable of receiving the oily internal phase substances and emulsifying at room temperature with the external water phase.

As well as the temperature test (30 days at 40°C, indicated with A), we also established a more severe test of stability by centrifuging at 3000 revolutions for 30 minutes. The result of this test is shown in the B column. First we shall try the GH-1 composition thus formed:

   SESAMULS© OW 35%
   Octyl Palmitate 35%
   Stearic Acid 30%
    Stability
    A B
   GH-1 10% Aqua 90% S S
  Octyl Stearate 10%, Aqua 80% S S
  Hydrogenated Poly-1 Decene 10%, Aqua 80% S S
  Buxus Chinensis (oil) 10%, Aqua 80% S S
  Octyl Dodecanol 10%, Aqua 80% N N
  Octyldodecyl Lactate 10%, Aqua 80% S S
  SILGREEN© C 5%, Octyl Stearate 5%, Aqua 80% S S
  Cannabis Sativa (Oil) 5%, Olea Europaea (Unsaponif). 5%, Buxus Chinensis (Oil) 5%, Butirosperm. Parkii 5%, Aqua 80% S S

The combination of SESAMULS© OW + Stearic Acid shows a good emulsifying capability. Only the presence of high polarity esters such as Octyl Dodecanol undermines the performance. In view of the excellent results obtained in this first series, we shall attempt to progressively increase the lipidic phase to 15 and 20%.

    Stability
    A B
   GH-1 10% Octyl Stearate 15%, Aqua 75% S S
  Octyl Stearate 20%, Aqua 70% S S
   GH-1 10% Hydrogenated Poly-1 Decene 15%, Aqua 75% S S
  Hydrogenated Poly-1 Decene 20%, Aqua 70% S S

Even doubling the quantity of the internal phase, the emulsions stability is still very good. The GH-1 system not only performs well with lipids of various polarities, but is also unaffected by the existing relationship between the phases. Even though unsuccessful in the previous series, lets add the cetearyl alcohol to the emulsion system.

The absorption base of the next series GH-2 consists of:

   SESAMULS© OW 2
   Octyl Palmitate 1
   Cetearyl Acid 1
    Stability
    A B
   GH-2 10% Aqua 90% N na
  Octyl Stearate 10%, Aqua 80% N na
  Hydrogenated Poly-1 Decene 10%, Aqua 80% N na
  Buxus Chinensis (Oil) 10%, Aqua 80% N na
  Octyl Dodecanol 10%, Aqua 80% N na
  Octyldodecyl Lactate 10%, Aqua 80% N na
  SILGREEN© C 5%, Octyl Stearate 5%, Aqua 80% N na
  Cannabis Sativa (Oil) 5%, Olea Europaea (Unsaponif.) 5%, Buxus Chinensis (Oil) 5%, Butirosperm. Parkii 5%, Aqua 80% N na

Emulsions prepared with the GH-2 system are extremely unstable and in many cases separate within 12 hours of preparation. The centrifuge test is therefore pointless.

Let us try the combination of Stearic Acid and cetearyl alcohol to make an emulsion system GH-3 thus formed:

   SESAMULS© OW 40%
   Octyl Palmitate 40%
   Cetearyl Alcohol 10%
   Stearic Acid 10%
    Stability
    A B
   GH-3 10% Aqua 90% S N
  Octyl Stearate 10%, Aqua 80% S N
  Hydrogenated Poly-1 Decene 10%, Aqua 80% S N
  Buxus Chinensis (Oil) 10%, Aqua 80% S N
  Octyl Dodecanol 10%, Aqua 80% N N
  Octyldodecyl Lactate 10%, Aqua 80% N N
  SILGREEN© C 5%, Octyl Stearate 5%, Aqua 80% S N
  Cannabis Sativa (Oil) 5%, Olea Europaea (Unsaponif.) 5%, Buxus Chinensis (Oil) 5%, Butirosperm. Parkii 5%, Aqua 80% S N

In comparison with the previous series, the stability has improved, but is still not acceptable. Even if in some cases the emulsion passes the heat test, none gets through the centrifuge test.

Let us try replacing glyceryl stearate as a partner for SESAMULS© OW. We have chosen a product of vegetal origin, with an average mono glyceride content of 60%.
The next series of emulsions based on the GH-4 system is thus formed:

   SESAMULS© OW 40%
   Octyl Palmitate 40%
   Glyceryl Stearate 20%
    Stability
    A B
   GH-4 10% Aqua 90% S S
  Octyl Stearate 10%, Aqua 80% S S
  Hydrogenated Poly-1 Decene 10%, Aqua 80% S S
  Buxus Chinensis (oil) 10%, Aqua 80% S S
  Octyl Dodecanol 10%, Aqua 80% S S
  Octyldodecyl Lactate 10%, Aqua 80% S S
  SILGREEN© C 5%, Octyl Stearate 5%, Aqua 80% S S
  Cannabis Sativa (Oil) 5%, Olea Europaea (Unsaponif.) 5%, Aqua 80% S S
  Buxus Chinensis (Oil) 5%, Butyrospermum Parkii 5%, Aqua 80% S S

With the GH-4 system, formed of SESAMULS© OW + Octyl Palmitate + Glyceryl Stearate, stable and very good quality emulsions are obtained, the best so far. The emulsion forms easily with no particular problems and the resulting product is fluid, of pleasant aspect and particularly stable.

Using as a base the previous results obtained using the GH-4 system, which produced low viscosity emulsions, let’s attempt to formulate a super fluid ‘sprayable’ emulsion, obtainable through a cold process production procedure.

   Hydrogenated Poly-1 Decene 3.0
   Octyl Palmitate 2.5
   Octyl Stearate 1.5
   Glyceryl Stearate 1.2
   Aqua 87.0
  SESAMULS© OW 2.5
   Diglycerin 2.3

The resulting emulsion has a very low viscosity, suitable for our idea of being sprayable. It has an evident ‘Tyndall’ effect and the stability is confirmed through severe and prolonged heat and centrifuge tests. It vaporizes easily, forming a homogenous, impalpable, light and extended mist. Once deposited on the skin it does not give an unpleasant ‘wet’ feel and disappears rapidly leaving the skin soft and dry with a pleasant fresh feeling. This simple formula is an excellent base for the study of sprayable emulsions.

We will base the next series of emulsions on the GH-5 mixture, thus formed:

  SESAMULS© OW 40%
   Octyl Palmitate 40%
   Stearic Acid 10%
   Glyceryl Stearate 10%
    Stability
    A B
   GH-5 10% Aqua 90% S S
  Octyl Stearate 10%, Aqua 80% S S
  Hydrogenated Poly-1 Decene 10%, Aqua 80% S S
  Buxus Chinensis (oil) 10%, Aqua 80% S S
  Octyl Dodecanol 10%, Aqua 80% S S
  Octyldodecyl Lactate 10%, Aqua 80% S S
  SILGREEN© C 5%, Octyl Stearate 5%, Aqua 80% S S
  Cannabis Sativa (Oil) 5%, Olea Europaea (Unsaponif.) 5%, Aqua 80% S S
  Buxus Chinensis (Oil) 5%, Butyrospermum Parkii 5%, Aqua 80% S S

The stability and quality of these emulsions formed with the GH-5 system is similar to those obtained with the GH-4 system. In some cases, the emulsions are whiter, but the overall organoleptic characteristics are the same as the GH-4 system.

The system is therefore not affected by the addition of stearic acid. We can conclude the experiment by attempting to substitute the Stearic Acid with Cetyl Palmitate in the emulsion. We made a last series of emulsions with the GH-6 system, thus composed:

  SESAMULS© OW 40%
   Octyl Palmitate 40%
   Cetil Palmitate 10%
   Glyceryl Stearate 10%
    Stability
    A B
   GH-6 10% Aqua 90% S S
  Octyl Stearate 10%, Aqua 80% S S
  Hydrogenated Poly-1 Decene 10%, Aqua 80% S S
  Buxus Chinensis (oil) 10%, Aqua 80% S S
  Octyl Dodecanol 10%, Aqua 80% S S
  Octyldodecyl Lactate 10%, Aqua 80% S S
  SILGREEN© C 5%, Octyl Stearate 5%, Aqua 80% S S
  Cannabis Sativa (Oil) 5%, Olea Europaea (Unsaponif.) 5%, Aqua 80% S S
  Buxus Chinensis (Oil) 5%, Butyrospermum Parkii 5%, Aqua 80% S S

Compared to the previous two emulsion systems GH-4 and GH-5, the product of this last system have greatly improved organoleptic characteristics. The Glyceryl Stearate proved to be the best partner for the SESAMULS© OW, allowing the preparation of stable and pleasant emulsions even in the presence of a very polar alcohol such as the Octyl Dodecanol.