Humectants compatible and incompatible with Carbomer?

Formulating

Humectants compatible and incompatible with Carbomer?

Posted by Zink on June 21, 2014 at 12:40 am

I was making a formula tonight and used 4% sodium lactate + 0.5% sodium carbomer (pre neutralized) in my water phase, I let the carbomer wet for 20 minutes and used a staff blender to mix it into the rest of the water phase.

My end lotion did unfortunately not thicken, come to think of it, it should have thickened with the emulsifier alone, perhaps Ewax NF doesn’t work well with Alkyl Benzoate C12 - C15 added?

Anyways, what humectants are good with Carbomer? Sodium Lactate, Sodium PCA, Hyaluronic acid?

Chemist77 replied 9 years, 10 months ago 4 Members · 8 Replies
8 Replies

Chemist77

Member
June 21, 2014 at 1:27 am

Though Sodium Lactate is a humectant but eventually it is an electrolyte and it is definitely not going to let the carbomer work to maximum.
Secondly I guess you could check some polarity index re the oil phase, might come handy on this one.
nasrins

Member
June 21, 2014 at 4:40 am

carbomer isnt enough to thicken ur lotion.
MakingSkincare

Member
June 21, 2014 at 5:51 am

Yes as milliachemist says sodium lactate is an electrolyte and unless you have the carbopol ultrez 30+ version, I would use glycerin as your humectant instead.

You could use a fatty acid/alcohol to thicken eg cetyl alcohol and that will also help stabilise your lotion. Ewax NF should work fine with C12-15 alkyl benzoate.
Chemist77

Member
June 21, 2014 at 7:11 am

Try making the same formula without the salt and see where you stand, shall clarify the things in one single step. You would know if the oil phase too is a problem or just the salt.
Zink

Member
June 21, 2014 at 5:43 pm

So the lotion thickened to a good thickness overnight, not at all runny. Will add 2% cetyl alcohol to the next test batch. Will do acc. stability on both and see how they hold up.
Chemist77

Member
June 21, 2014 at 9:28 pm

@Zink OK the lotion thickened up, but what corrective measures you took???
Zink

Member
June 21, 2014 at 11:06 pm

Nothing, it took 12 hours to thicken, possibly the carbomer gelling up further.
Chemist77

Member
June 22, 2014 at 12:33 am

Auto correction of pH I suppose and which was not possible during the initial stages because of the strong presence of electrolyte (4% you mentioned). With the overnight hydrolysis (dilution of electrolyte), guess the solution has attained optimum pH and electrolyte concentration for the thickener to regain its thickening efficiency.

Could this be the reason or is it entirely something else???????