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Foamable emulsion
Hi, does anyone have tips on making my o/w emulsion into a foamable product using an airspray foam pump? I was able to make a stable emulsion using tween 80 and span 60 in my oil phase. The concentrations of these surfactants/emulsifiers were determined by the oil’s Required HLB of 8. My aqueous phase has ethanol, glycerin, lactic acid and water. The problem is that this formulation produces absolutely no stable foaming. I added DSCAD as a foam booster, but that didn’t help, either.
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7 Replies
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My first observation, is that you have no surfactants in there, unless there’s something you’re not telling us. Ingredients such as ethanol and glycerin are anti-foaming so it’s hardly surprising the results you describe. A better approach might be to use a polyoxyethylene/surfactant type emulsifier such as Emulgin which does contain a surfactant.
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hmm, that’s a difficult one; foaming products and emulsions usually work against each other
however, you can by adding a little bit of a foaming surfactant to the water phase, e.g. SLES, and a suitable protective colloid to stabilise the emulsion - I’ve done this with cream hair dyes so they wash out more easily
be careful not to add too much of the foaming surfactant, or else it’ll compete with the emulsion for the available water and cause separation
and @Belassi is right, alcohol will kill the foam completely
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Are there any high foam surfactants with low hlb that you would recommend? Since the surfactant will be mixed with my water phase, does its’ hlb matter? I would prefer non-ionic surfactants.
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Perhaps sodium lauroyl lactylate as co-emulsifier and hydroxypropyl methylcellulose as foam stabilizer?
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try an alkyl glucoside (decyl glucoside, lauryl glucoside, coco-glucoside etc.)
low HLB surfactants don’t foam, and because foaming surfactants are generally not effective as emulsifiers, their HLBs are irrelevant
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Get rid of the alcohol if you can. Then try adding SLS in 1% increments.
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In addition, ionic surfactants (SLS, SLES, sodium lauroyl lactylate) do not have an HLB (or do not adhere to the HLB system).
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