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HLB: calculate or not to calculate?
Hello all!
There are
controversial opinions about HLB system. Some say it’s outdated, only works for
non-ionic emulsifiers and doesn’t respond to questions such as how much
emulsifier to use, thus it makes no sense to use it.Others say it
is an important starting point and should be applied.I guess I have
good “intuition” and none of my emulsions has ever separated (within one month at
least, excluding experiments where I wanted to establish a point where it separates) no matter if I calculated HLB or not.I understand
that it can be ignored when using commercial emulsifiers’ blends but what about
the situations where the formulator is trying to create a custom blend of
non-ionic emulsifiers (Say polysorbates and liquid low HLB emulsifier)?Is there a
reason to apply HLB system or not? All opinions are appreciated.Thank you in
advance.Narmina
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3 Replies
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The times I’ve used a HLB calculator I can count on one hand. It isn’t very useful to me.
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Emulsion science is all about amphiphilicity and how surfactant
behaves at the interface. HLB is very simple system that give a number to the surfactant
and not to the system, without taking into account interaction with other
ingredients of the formulation that interfere with interface such as alcohols,
electrolytes, polarity of the disperse and continuous phase, and phase behavior
components such as composition and temperature (that last condition explain why
HLB fails for ethoxylated surfactants)… that why it will only give partial
indication on the selection of the surfactant, and in many case it fails … This
will be the case if you only calculate the required HLB and match it with the
HLB of the surfactant, nevertheless, there is experimental method to determine
the required HLB that are maybe more accurate. Calculating is a good starting
point when you have no idea.We can start a new study to have a statistical result
to know what give better results HLB or intuition. Since I believe in science, I
believe HLB, even as simple it is, there is science in the concept. I also believe that luckily intuition (you may
refer by intuition to experience?) do a good job because nowadays they is very
great and efficient surfactants system on the marketOther concept take into account more interaction of the system, that
is the case of the HLD (Hydrophilic Lipophilic Difference) developed by Salager
and PIT (for ethoxylated surfactants) developed by Kunieda. Unfortunately the application
of these concepts is more complex, and discourages many formulators in their
daily work. -
I have been formulating with HLB in mind for the first year (after I just started). Then I was told by more experienced people who reviewed my formula that adding glyceryl oleate to bring HLB of the system (glyceryl stearate/PEG-100 stearate that has HLB of 11.5) down to 7-8 (which is HLB of most veg oils) is a bit overkill. But I still see advices of professionals on this forum to calculate HLB.
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