Proper Procedure for Pigment Wetting — Cosmetic Science Talk

Proper Procedure for Pigment Wetting

edited January 4 in Color and makeup
Hey all,
I'm having some issues with some pigment agglomeration in a hot pour product. I'm using lecithin coated pigments. There are little speckles of coated TiO2 (and just TiO2, no iron oxides) throughout the cooled product. I'm using both Finsolv TN (wetter) and Cithrol PG23IS (disperser) and I noticed significantly less speckling after the addition of both, but it still remains. Finsolv is in at 5% and the Cithrol is in at 2%. Product is poured just above set temperature.

For proper pigment wetting do you mix pigments with the wetter and then introduce the rest of the product into the pre-wet pigments and disperse, or is adding the pigment wetter to the overall mixture and then dispersing pigments with IKA enough?

While during my searching I found a lot of stuff about why you should wet pigments but not the *how*.

I know I'm asking a lot of questions and I appreciate all you guys' help.

Comments

  • edited January 4
    I wanted to add that I tried pre dispersing the pigments in a massive amount of Finsolv and I still got the little speckles. The speckles don't streak at all so I'm wondering if it *isn't* the TiO2... though I never got the speckling when using pigments treated with a silane so I hesitate to say it's anything else in the formula either. I tried a formula without ascorbyl palmitate and it still speckled and I don't think there's enough nylon for it to do that.

    Most recent formula (rounded percent):
    5% cap/cap
    5% DC 556
    1.5% Tribehenin
    6% Ozokerite
    1% Ceresin
    1% Squalane
    1.5% Tridecyl Trimellitate
    .75% polyglyceryl-3 beeswax
    1% soft jojoba ester
    4% hard jojoba ester
    2% Cithrol disperser
    17% Finsolv (like I said, massive)
    0.5% K-82P polyester
    10% Vegelight 1214LC
    0.5% Nylon-12
    0.7% antioxidant
    0.1% ascorbyl palmitate
    rest is pigments. Supposed to be a concealer stick.
  • Try it without the TiO2.
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • edited January 5
    I don't know what your batch size is, but maybe this is an idea:
    - take a mortar + pestle with roughened surface;
    - put a bit of wetting agent and spread it in the mortar (to prevent pigment from adsorbing to surface too much);
    - disperse pigment with same quantities of wetting agent.
    (edit: so don't use a huge amount of wetting agent with a tiny bit of pigment, but in same quantities or you'll never get a homogeneous end result.)

    This is how I used to disperse pigments in the pharmacy.
    Good luck!
  • A note of caution:
    I would always use a wetting agent when dispersing coated pigments in rough mortars (i.e. don't grind/pulverize them as you might damage the coating which could result in a change of colour.) Maybe this warning is for mica's only or all coated pigments, I'm not sure.
  • edited January 5
    @Bobzchemist
    Okay, I'll make a batch without TiO2 to check. If it ends up being TiO2 maybe I can order some NJE pigments from Kobo as the client does not want to go back to silane (wants silicone free product, hence vegelight instead of D5).

    @Doreen81
    Unfortunately anything I do will eventually need to be mirrored by our large scale production crew and I don't think we have anything like that for large batches :( 

    Thanks guys!
  • Confirmed it's the TiO2, gonna try the jojoba ester pigments next. 
  • Sometimes, the treatments are so sticky that the pigments clump up. Try mixing them dry in a blender together with the nylon before adding them to your batch. Also, an IKA homogenizer isn't the best option for dispersing pigments.
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • edited January 10
    @Bobzchemist
    Unfortunately IKA is what we are stuck with, we have IKAs of all sizes including giant ones for production that I'm sure management will be hesitant to replace. What is best for pigment dispersion? I know you are a consultant so feel free to brush the question off if it's too in depth to count as free advice :)
  • When dispersing pigments, you want to use the thickest mixture that your mixers can handle. Particle-to-particle interaction can help improve the dispersion.

    If you were buying new equipment, a ball mill, 3-roll mill or colloid mill would be ideal. Next best would be a Cowles dissolver.
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
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