[MakingSkincare]

You might find it useful to look through the 27 preservative reviews here - http://makingskincare.com/preservatives/ to find one that suits

[MakingSkincare]

To create an emulsion you need high shear forces in the liquid, which are necessary to create small particles and therefore stable emulsions. So greater mixing intensity, especially with respect to impeller tip speed, will create smaller dispersed phase droplets, which should help create a more stable emulsion. 

I would go for a saw-tooth disk impeller to emulsify because it can transfer the power to the liquid as shear force with little pumping. The tip speed may need to be 0.5 to 1.5 m/sec.  A tip speed (velocity at the tip of the impeller) of 1 to 3 m/s is common for liquid-liquid dispersion.  At these tip velocities, strong shear gradients are formed in the fluid, resulting is drop break-up and dispersion.  Nominal drop sizes from 20 to 80 microns are possible with these tip speeds, but the physical properties of the fluids have a strong effect on these results. High-shear mixers can be of several types eg saw-tooth disks, rotor-stator devices, colloid mills and high-pressure homogenizers.  A combination of a high-shear saw-tooth disk impeller and an anchor impeller may provide the combination you need.

You can buy these attachments to add to your mixer (or high speed drill) from indco and IKA.

[MakingSkincare]

I would go with a preservative blend such as: 0.5% Phenoxyethanol, 0.3% Methylparaben and 0.2% Propylparaben plus a chelator, for example, disodium EDTA and design your packaging so it minimises contamination during use. 

[MakingSkincare]

Some info - http://swiftcraftymonkey.blogspot.co.uk/2010/06/conditioners-leave-in-conditioners.html and http://swiftcraftymonkey.blogspot.co.uk/2010/06/conditioner-defining-our-conditioners.html

[MakingSkincare]

You can download one from here - http://makingskincare.com/hlb-calculator/

[MakingSkincare]

Some info - http://www.koboproductsinc.com/Downloads/Formulating_natural_sunscreen-March2009.pdf and http://www.creative-developments.co.uk/papers/Factors%20affecting%20sun%20care%20formulations.html

[MakingSkincare]

I presume this is a room/linen spray so my comments are geared towards that.

You will need to add a preservative - preservative choices here - http://makingskincare.com/preservatives/

As a solubilizer, try polysorbate 20 at 12% and if that doesn’t do it keep increasing the % until it does solubilise (different essential oils/combinations need different amounts of poly).

[MakingSkincare]

Sounds like a LOT of actives to me.  Why such a high % ? More is not always better - you only need enough to make a noticeable difference.  If you look at professional formulas you will find that the % of actives is much, much lower than 50%. I would also advise reducing the % drastically for the emulsion to be safe, not cause irritation, be stable and be able to preserve it.

If the ingredient isn’t heat sensitive, it’s best added to the appropriate heated phase for a more stable emulsion.

Re soaping - sounds like the waxes are not solubilized enough. Wax emulsifiers often need to be solubilized to reduce waxiness. One way to do this is by adding polar ester oils so I’d probably add IPM or a solubilizing ester oil. Try dimethicone too.

[MakingSkincare]

Ben, thanks so much for your response.

Re leucidal, that was my conclusion too - in the absence of independent studies confirming that it’s broad spectrum, I don’t recommended it on my preservative review page.  Ditto with the GSE.  Bobzchemist - would be great to see what your testing reveals.

Great point about adding a chelator Bobzchemist.  Reducing the amount of “bug food”, unbound water and adding auxiliary ingredients such as glycols also helps.

[MakingSkincare]

Thanks so much Ben.  

Preservation is such a complex and fascinating area (I’m confessing to being a bit of preservative nerd!).  I’ve written reviews on commonly used preservatives and am always looking for more info.  I’ve got a few more questions - I’ll just concentrate on the key ones here and if it’s OK I will message you a couple of other questions, since I don’t want to hog your post.

Does polysorbate 60 also neutralize substituted phenolics?  A lot of people in my group use ewax which contains it.

The questions below, are obviously formula dependent…

what would be your overall opinion of naticide or leucidal liquid (incl the SF version)? I have been cautious not to recommend them as I have not seen independent studies on their effectiveness. 

Thanks again Ben for your kind help. 

[MakingSkincare]

Thanks for listing the INCI of your other ingredients milliachemist.  I would still say your emulsion is anionic.  

[MakingSkincare]

I think it would depend on the charges of the other ingredients and their function. You mentioned GMS SE which I know is anionic but would be helpful to know the INCI of the other ingredients.

Normally GMS SE is paired up with a high HLB emulsifier for o/w (if your emulsion is o/w).

[MakingSkincare]

the GMS SE is anionic so personally I wouldn’t label the emulsion non-ionic.

[MakingSkincare]

Hi Ben

Welcome back to the forum.  Thanks for offering to help - I would love to have your views on some points made in this article - 

http://www.americanpharmaceuticalreview.com/Featured-Articles/38885-Antimicrobial-Preservatives-Part-Two-Choosing-a-Preservative/ specifically…..

Benzyl alcohol and phenoxyethanol should not be formulated with non-ionic surfactants eg polysorbate 80. They will interact and such interactions may not involve conventional chemical transformation, but concern more subtle phenomena e.g. hydrogen bonding and complex formation. Thus the overall level of preservative in the product may not change, but unless the preservative is available in the “free” form its efficacy may be compromised.

The article also states:-

EDTA can interact with benzoic acid ….and..

Adsorption onto excipients, especially those with large surface areas or on to container / closure systems can also remove preservative(s) from solution for example
- benzoic acid by kaolin
- phenoxyethanol by pvc plastic, cellulose based excipients
- sorbic acid/sorbates by plastics (polyproylene, PVC and polyethylene)

The antimicrobial efficacy of phenoxyethanol is reduced in the presence of the cellulosic suspending agents such as HPMC.

I’m wondering what your experiences are with the above and whether you agree with points raised in the article?

[MakingSkincare]

Try using lotionpro 165 (peg100stearate+glyceryl stearate) as your emulsifier (o/w), as it’s good with acidic ph. 

[MakingSkincare]

dormex.co.uk but you will have to chase them a lot

[MakingSkincare]

Thanks Robert - I’m not on Linkedin but I will join. 

If you’re on facebook we would love to have you (and anyone else who wants to join) (a couple of your cosmetic chemist pals here are also members) - https://www.facebook.com/groups/makingskincare/

[MakingSkincare]

This should help explain - http://cavemanchemistry.com/DreadedOrangeSpot-Dunn.pdf

[MakingSkincare]

looks great Simona. Let us know how the testing goes.

[MakingSkincare]

Robert - what is your group - I’d like to join? and I promise I WILL contribute!!

I also run an active group/discussion forum which incl cosmetic chemists - - https://www.facebook.com/groups/makingskincare/

[MakingSkincare]

Obviously depends on the formula but here’s a run down of some common preservatives and what they cover including those considered “natural” (approved by Ecocert) - http://makingskincare.com/preservatives/

[MakingSkincare]

Crossing my fingers that you can get them back.  Lots of very valuable discussions.

[MakingSkincare]

arctat - yes do experiment with it.  For me, at 0.5% it works if I add it at the very end of the heated water phase. 

[MakingSkincare]

Try it at 0.5% - it should be fine at that level.

[MakingSkincare]

Montel, if you’re looking to learn to create your own cosmetics then swiftcraftymonkey’s blog is a great way to learn and she has formulas on her site too which you can tailor.