[jeremien]

I try with Xanthan Gum, but final formulation look more heavy (more dense) compare with carbomer one. I’m looking for a very light effect of the final product

[jeremien]

@Bobzchemist, i have also a sample of permulen, i will try. With only 5% oil, do you really think i need to boost the emulsification?

[jeremien]

@Bill_Toge  yes , i cannot understand the different behaviors, I
guess that it is your second answer, that the material i m using is not really
cetearyl alcohol. I’m using a sample that I received from KAO, the Kalcol
6850. 

Another scientific explanation, is that with the cetearyl  alcohol decreases
more the phase inversion temperature than the cetyl alcohol, and I start to
invert the emulsion at 75ºC with the cetearyl alcohol, but in my case I’m not
using ethoxilated surfactants so it sound highly unlikely.

@ johnb,  thanks, i will try the Carbopol 934 or new versions of carbopol (carbopol smart?)

[jeremien]

@johnb thanks for the recommendation. I use the carbopol 940
only for the viscosity building effect with limited concentration that gives
this very nice aqueous gel aspect (white because of the emulsion but I don’t
care in this case to obtain a transparent gel)
Interestingly, i have repeat the formulation changing the cetearyl
alcohol by the cetyl alcohol, and in this case, i obtain a stable homogeneous
formula. 

[jeremien]

@Perry , i have checked and it is not regulatory banned, only negative image, and comercialy banned in many products (e.g. baby care).

[jeremien]

phenoxethanol could be banned in cosmetics soon  (i guess in France it is already banned)

[jeremien]

cetyl alcool and cetearyl alcohol are both co-emulsifiers. They change the curvature of the surfactant at the interface Oil/water. 
i’m wondering by which mechanism the cetearyl alcohol is thickening the continuous phase?

[jeremien]

@Bill_Toge  I agree with you. Of course the chemical structure of your surfactant is important to understand
the difference in properties (maybe in that example, the PIT (phase inversion temperature) could be the best system to explain the differences).

I guess my comment was confusing, i mean  there is no sense to add a minimum
size (the same as a maximum) to the definition of a surfactant.

[jeremien]

I guess that any amphiphilic molecule can be
considered as surfactant. Of course you cannot stabilize emulsion with short
chain alcohol, but they can be considered as co-surfactants as they have
affinity for the interface.

 I don ‘t know if there is a definition
linked to a specific value of surface tension that have to be reached to
consider a molecule as surfactant. 

In my opinion,  there is no point to describe a surfactant by
its size (unless you want to demonstrate the kinetic of interface adsorption or
for large molecules steric stabilization), HLB or other scales that describe
the amphiphilicity of the molecule are more convenient to describe surfactant
molecules.

[jeremien]

@Bobzchemist you are totally right, and the same comment is valid for the surfactant that many time is overloaded

[jeremien]

@MarkBroussard  I beleive you. I use to put 3 % of pure glycerin  (and you have to add the glycerin of glycerin based ingredients) in most of my products and they are not sticky. Most of the orientative formulas that ingredient suppliers send me (Croda, Dow corning, DrStaetmans, Gattefosse, etc.) have glycerin level between 2-5%  

[jeremien]

Most of the Cream/gel/lotions contain between 3 and 5% glycerin

[jeremien]

Stator/rotor homogenizers, allow to decrease the droplet size and decrease polidispersity, two parameters very important for stability. As many cosmetic formulas contain polymer to give viscosity to the continuous phase, most of the time you don t care about  your emulsion droplet size distribution.

[jeremien]

@Bobzchemist  High-pressure homogenizer unsuitable in cosmetic; except if
 you want to prepare nano-emulsions 

[jeremien]

That’s right Johnb, if you want to scale your batch,
in the industry rotor/stator mixer are not commune as they are voracious
and expensive consumer of energy. So better to tune process/
surfactant system, to emulsify with propeller mixer

[jeremien]

Depends of your surfactant system. If it decreases a
lot the interfacial tension between your oil and aqueous phase (below 10mN.m-1)
you can form your emulsion almost spontaneously.

In case of concentrated emulsions you can also emulsify by
low energy method by stepwise addition of your oil phase to water (O/W emulsion)
like a mayonnaise.by this method and choosing the good surfactant system you
can reach almost 99% of dispersed phase in your emulsion if you want. 

With ethoxylated surfactants you can play with
temperature and prepare emulsion by phase inversion temperature. In this case
you need only weak agitation. This method takes advantage of the change of
curvature of your surfactant with TºC so you can pass from W/O to O/W emulsion
by simple cooling or heating.

All these technique need some phase behavior study of
your surfactant system with oil and water.

[jeremien]

stability tests at 4ºC, 25 and 40ºC, the test depends of your formulation

[jeremien]

Thanks

[jeremien]

It’s not related to emulsion stability, but emulsion formation. Stability is related with zeta potential, steric stabilization, viscosity of your phases, etc. 

[jeremien]

low surface tension for emulsion application (below 30
mN.m-1) and ultralow for microemulsion application (<1 mN.m-1). The lower
the surface/interfacial tension less energy you have to apply to your system to
emulsify. 

[jeremien]

What is your oil phase?

[jeremien]

you are right, i mean strong ionic strenght species such as polycations or ionic surfactants.

[jeremien]

Thanks for your quick answers. Well i’m a bicosome
partner, but i’m not mention on the website (not important enought).

i just want to encapsulate vitamine B3, so normally
no problem with regulation, and still remain in the scope of cosmetic products

I understand that  silicone elastomer gels have to be use to give viscosity to an oil. In my case i would avoid use of oil in my formulation, hydroxyethylcellulose sound good choice

[jeremien]

Dear johnb, 

I’m trying a very innovative ingredient called
bicosome that is loaded with soft anti-acne ingredients, and i would like to
test it in a basic formulation like an hydrogel to test efficiency. 

[jeremien]

Dear zink,

Indeed, the formula you send corresponds to a
simple dispersion. Liposomes are a good option of soft encapsulation, but it
will not give you any efficiency in term of skin penetration. Check the
bicosome technology (www.bicosome.com), soft encapsulation able to target the
layer of the skin where you want your active to be active.

 

Bests,