Pigment Dispersion - Lab Scale

klangridge

Hi all,

I was wondering if anyone has tips for dispersing pigments in the lab? I am making a concealer (W/O) and just can't seem to get my TiO2 and iron oxides to disperse completely - when I try out the finished formula I end up with white dots and yellow / black / red smears on the skin!

I have been adding my pigments to the oil phase before homogenising with the water phase. I have added VP/Hexadecene Copolymer which is a pigment dispersant, but I don't think it's effective enough to help with the large amount of pigment used in a concealer/foundation formula. I have also tried a high shear stirrer impeller with cog-like zig-zag edges which they use in the paint industry and it doesn't seem to have helped.

Does anyone have any tips for dispersing in the oil phase? Any suggestions appreciated!

ngarayeva001

I spent a lot of time and money to come to the conclusion that it's a terrible idea. You will not be able to do it in a small lab setting unless you are happy to spend a lot! on equipment. You have two options: 1) Buy coated and pre-dispersed TiO2 and Iron oxides separately 2) Buy coated and predisperced blend for foundations. The innovation company has the creasperce range. 
https://theinnovationcompany.fr/products/creasperse-bb/

Their MOQ is 5kg but I know two repackagers in the EU where they sell smaller amounts if you need it. I only buy them for my own use, and what I end up doing is buying two neutral colours (light and dark) and mixing them to colour match.

ngarayeva001

https://www.glamourcosmetics.it/it/gc-base-bb-cream-creamy-nude
https://www.glamourcosmetics.it/it/gc-base-bb-cream-warm-beige

https://www.manischemicals.com/en/inorganic-colors-oxides/1826-2962-creasperse-bb-vs-30gr.html#/736-color-light_fair_beige (they also have dyes and other colours)

More expensive and tricky option:

https://trulux.com.au/kobo-mt-500b-nje5/
https://trulux.com.au/kobo-black-fand60bsi/
https://trulux.com.au/kobo-red-fand55rsi/
https://trulux.com.au/kobo-yellow-fand45ysi/

Or, if you feel adventurous and really want to make it from scratch, get coated! pigments from glamourcosmetics or tkb trading, disperse in something like hydrogenated polyisobutene, add polyhydroxystearic acid and disteardimonium (low polarity oils)/stearalkonium (high polarity) hectorite and hope for the best. Been there, tried it is better than uncoated but not on the same level as a premade blend. I strongly advise against it.

ngarayeva001

By the way, get disteardimonium hectorite and polyhydroxystearic acid anyway. They make a difference.

klangridge

Hi @ngarayeva001, Thank you for that! I honestly wasn't expecting such a detailed answer.

I do have disteardimonium hectorite in the formulation as well, but you're right - it seems that even with the right ingredients (or some of them) I'm not getting far and would probably have to buy some expensive equipment to do so!

I'll have a look into the Creasperse range and Kobo as well - I think I'd rather do the colour mixing myself if I can purely for experience.

Thank you so much for your help!

lewhitak

First try grinding down the native pigment to the finest you can by using a coffee or spice grinder from Amazon. After this, you can disperse the dry pigments using a glass muller or other paint tools (like this) in your oil phase to wet out the pigment properly. Use high shear to add to your formula. You would need to characterize your grind to make it reproducible with a grind gauge or similar. 

You will likely need to fiddle around with the mix times to find how you can achieve the best grind. 

Orrr as @ngarayeva001 suggested you purchase pigments where the work has already been done and make your life a heck of a lot easier.

ngarayeva001

@klangridge, I spent so much time and effort trying to make it myself that I think I have to at least share my experience with someone who is in the beginning of this journey. I understand that you want to mix from the scratch for the sake of experience. Have a look at what is included in creasperse except for the pigments. I recall it’s polyxydroxystearic acid and some of the hectorites. Try to make your own liquid blend from coated dry pigments (I am sure there’s coated TiO2 on tkb, not sure about oxides) and dispersing agents before adding it to your concealer (making all at once is challenging) Dry pigments can be mixed together in a coffee grinder as @lewhitak suggested above. I noticed that anhydrous concealers are a little more forgiving when it comes to quality of pigment.

Shams

Pre-grind your pigments using a coffee grinder. And then disperse them in your oil phase and complete the rest as usual. You will need to homogenise your formula as well using a stick mixer while the product is in a paste-like consitency while cooling down(not too hot, not room temperature) to ensure it is grinded well and completely dispersed in the formula. This is how I usually do it on lab scale and it comes out perfect . And this is not with pre-treated pigments

ngarayeva001

@Shams , 
‘Perfect’ is a very vague definition. Perfect for what? Try to make a w/si foundation with untreated oxides and get it through a stability test. You are inviting a variety of problems by doing this. Untreated oxides will break the emulsion after a while, red oxide will start bleeding  out of the emulsion, they will precipitate, separate in all possible ways and forms. You probably can make not too terrible anhydrous balm with such blend but it won’t be close to commercial quality. Maybe ok for personal use if you aren’t picky. Pigments are tricky beasts.

ngarayeva001

I am not discouraging anyone from experimenting. At the end of the day it’s not a sunscreen or some low ph acid peel where you have no room for error. It’s good to know how to blend your own. It’s a cool feeling to know you can recreate color of human skin by mixing 4 colours that look nothing near to human skin. Just be prepared for wasting some materials and time.

klangridge

@lewhitak @ngarayeva001 @Shams ; Thank you all for your inputs - really useful to have a few different options. For now, I have some coated pigment samples on order and will try to disperse those myself, and will look at the coffee grinder. If I have trouble with that I'll look into pre-dispersed pigments.

ngarayeva001

Good luck and let us know how it goes