Cationic & viscosity troubles

Meemcha

Dear chemists, I desperately need your guidance
I have been playing with cationic emulsifiers and trying to make a fancy hair mask, but there is some weird hocus-pocus going on in my concoctions. I have tried a gazillion of knock-outs and formula variations, but been facing more or less the same viscosity issue - my product goes from thick cream to fluffy milk as soon as I add anything that contains sodium benzoate. At least that is the only repetitive pattern so far. Here is the last formula variation:

4%         Oil (tried several)
5%         Isopropyl myristate
3%         Behentrimonium chloride
2%         Stearamidopropyl dimethylamine
7%         Cetyl alcohol 
68.65%  Water
5%         Propylene glycol
1%         Polyquaternium 7
0.5%      Hydrolized keratin
0.25%    Cetrimonium chloride
1%         Citric acid
0.2%      Sodium phytate
0.9%      Euxyl PE9010 (Phenoxyethanol&Ethylhexylglycerin)
0.8%      Geogard 221 (Dehydroacetic Acid & Benzyl Alcohol & Water)
0.7%      Fragrance

I started at 3% fatty alcohol and tried cetearyl, both together and brassica alcohol. Brassica was a complete watery fail. With cetyl alone at 7% the viscosity change is from thick cream to fluffy cream. I was initially going to use P. Sorbate and S. Benzoate blend instead of Geogard, but, upon addition the cream first becomes thicker and grainy, then goes fluffy and runny within seconds. I tried adding citric acid to the water phase and in cool down and I found the texture much thicker and nicer with the latter (pH 4.5-5). Silk proteins turn it watery, rice proteins too but to significantly lower  extent, whereas Polyquaternium 7 slightly kind of softens it. These three only have sodium benzoate in common.  Red algae extract (preserved with Naticide) turns a perfectly shiny cream to a grainy pile of c*ap and all mixers of this world are helpless. 
I see these ingredients on LOIs all the time and sodium benzoate is almost always there. Fragrance addition also affects viscosity in a similar manner. Tried with polysorbate 20, even worse. I have been measuring pH between every addition and the change was +-0.5. What is wrong with this formula? 

Obviously, I can eliminate all the culprits, and will probably end up doing so, but why is this happening? 

Perry

It's probably an electrolyte problem. Anionics (sodium benzoate, sodium phytate) and cationics (behentrimonium chloride, cetrimonium chloride) shouldn't be used together. The problem is easily solved by using DMDM Hydantoin instead of sodium benzoate.

Meemcha

Perry said:

It's probably an electrolyte problem. Anionics (sodium benzoate, sodium phytate) and cationics (behentrimonium chloride, cetrimonium chloride) shouldn't be used together. The problem is easily solved by using DMDM Hydantoin instead of sodium benzoate.

Thank you @Perry! I have been thinking of that, but I decided to give it a try as I am seeing them all the time with BC and CC and was wondering how others overcome this issue. Do you have any suggestions for a suitable chelate here?

Perry

EDTA perhaps

Meemcha

Perry said:

EDTA perhaps

Thought so. Thank you Perry!

ngarayeva001

It would be much better if you swap those oils to silicones (not 10%, like 3-4)

Meemcha

ngarayeva001 said:

It would be much better if you swap those oils to silicones (not 10%, like 3-4)

@ngarayeva001 I am testing both versions, oils vs. silicones and was planning to compare results. Just ordered EDTA and DMDMH, and will continue testing when I get them. I remember reading your posts about your attempt at a hair conditioner/mask. Have you done any formula updates recently?

Gunther

Is that a hair conditioner or a skin cream?

If it's the former, then why it contains oil, isopropyl myristate, propylene glycol, Sodium phytate and keratin?
They do nothing in a rinse off product, increase cost and may destabilize the product.

Why so much citric acid?

You can try some cetyl + cetostearyl alcohol instead of just plain cetyl, it makes the emulsion more stable, albeit the texture is slightly different.

Meemcha

Gunther said:

Is that a hair conditioner or a skin cream?

If it's the former, then why it contains oil, isopropyl myristate, propylene glycol, Sodium phytate and keratin?
They do nothing in a rinse off product, increase cost and may destabilize the product.

Why so much citric acid?

You can try some cetyl + cetostearyl alcohol instead of just plain cetyl, it makes the emulsion more stable, albeit the texture is slightly different.

It's an attempt to create a sort of 2in1, rinse off detangling conditioner and anti-frizz leave-in product. I did some research on some existing popular similar products and built the ingredient list around them. I was planning to make a version with silicone and compare them.
That is roughly how much CA it took to keep the pH in 4.5-5 range.
Already tried cetyl-cetearyl combo in various ratio and I still find the texture with cetyl only nicer and smoother. But I will try this combo again with EDTA and DMDMH. Thanks Gunther

Bill_Toge

if you want to use sodium benzoate you'll need a secondary, non-ionic emulsifier (e.g. ceteareth-20), both for increased electrolyte tolerance and for stability

Meemcha

Bill_Toge said:

if you want to use sodium benzoate you'll need a secondary, non-ionic emulsifier (e.g. ceteareth-20), both for increased electrolyte tolerance and for stability

Switching to DMDM Hydantoin

ngarayeva001

@Meemcha, I have been working on a conditioner for a while. I had an idea to make it in W/Si format (for a leave-in product) but it wasn't a very realistic exercise. Currently, I am trying to reverse engineer https://incidecoder.com/products/wella-professionals-invigo-nutri-enrich-mask. In my opinion, silicones add a lot to any conditioner (rinse-off and leave-in), so I always add them. My favourite for conditioners is amodimethicone. D5 is nice as well, but I am trying to be environmentally friendly when it's possible, so I use D5 for leave-in serums only. Phenyl trimethicone is also great for leave-in hair products. It's light and adds shine more than others

Vnnil

Propylene glycol tends to reduce viscosity of conditioners. Depending on its function, you could substitute it for glycerin.
Also, hydrolyzed keratin and Ethylhexylglycerin tend to destabilize conditioners.

Meemcha

@ngarayeva001 ; Thanks for the suggestions. Will get amodimethicone. Have you tried cyclopentasiloxane&dimethiconol blend? 

@Vnnil I've already tried that and had same issues. But anyhow, I will have 
repeat the same tests with DMDMH as the only preservative. And I tried adding keratin alone to an unpreserved sample and was okay at 0.5%, but I did notice change in viscosity at >1%.
I also tried adding only Euxyl before any cool-down phase ingredients and it didn't affect viscosity. Will post update here how it went with DMDMH.

ngarayeva001

@Vnnil, thank you very very much for this information! I know that Cetrimonium Chloride reduces the viscosity of conditioners quite significantly, but I had no idea PG can cause this too.

Dr Catherine Pratt

Maybe use some well known emulsifiers primary and secondary. If the ingredients lists use no go ingredient like Na Benzoate like Perry was talking about, these ingredients could have come from ingredients they have used that already were preserved with that ingredient. Does that make sense? Like a hydrosol for example.

Meemcha

@Dr Catherine Pratt that makes perfect sense and I did take it into consider. However, in one of the knock-outs with this formula, I added 1% Polyquaternium 7 preserved with sodium benzoate before any other cool-down phase ingredients and preservatives and it still affected viscosity. And a few days ago I was at the local dm store reading conditioners' LOIs and saw one containing behentrimonium chloride, cetrimonium chloride and sodium benzoate as the only preservative. It got me even more confused

Gunther

Adding more fatty alcohols (like cetyl, stearyl, cetostearyl), usually increases viscosity and emulsion stability.

ngarayeva001

But careful with this, because conditioner should be slippery and too much of fatty alcohols change the texture and make it draggy as if you apply a body lotion on your hair. I am still looking for that perfect balance, but it seems to me that 5% of Cetearyl alcohol is an absolute maximum.