[Iaskedbetter]

@luiscuevasii I am sure all of the senior/experienced chemists on this forum have, at one point or another, come across a something that inexplicably worked really well. Conversely, we all come across formulas that are supposed to work, but for some reason don’t. A big part of the formulation process is experimentation. Figuring out what works and what doesn’t and using the results to progress the development of a product.

With that said, I can’t tell you if you have the necessary materials for a stable emulsion (especially because I don’t know what processing equipment you have). The formula I gave you is where I would start if I was in your shoes trying to accomplish what you are asking for (although I do not know how that formula would cost out for you).

In addition to what @Vitalys said regarding TEA, it is a strong base (pH) and it is necessary to neutralize the carbopol in the formula I provided. When you add it, you should notice an immediate increase in viscosity.

Regarding your stability question, 90% of the formula appears “stable” because the free water molecules haven’t had enough time to coalesce. I’m willing to bet that if you give that formula enough time, you will see a complete separation.

[Iaskedbetter]

It doesn’t look like your formula has any emulsifiers at all…

Parrafin Oil - Oil/Humectant (Required HLB)

White Paraffin Wax - Thickener (Required HLB)

Stearic Acid - Thickener (Required HLB)

Cetyl Alcohol - Thickener (Required HLB)

Borax - Buffering agent (Adjusts pH)

The 1 week of stability you’re seeing is likely just steric hinderance (the thickeners are slowing the water droplets movement just enough that they can’t coalesce for ~1 week).

Of your available ingredients, tween 80 is the only real “emulsifier” and it is not suitable to be a primary emulsifier in a cream/lotion (at least not to my knowledge). Carbopol can work wonders for emulsion stability (while not technically an emulsifier) so you will certainly need to include that if you are going to find a solution to your problem. I would try the following and see where this gets you

Phase A

Water - QS

Carbopol - 0.3%

Glycerin - 2.0%

Phase B

Paraffin Oil - 15.0%

Cetyl Alcohol - 3.0%

Stearic Acid - 2.0%

Tween 80 - 1.0%

Phase C

TEA - 0.4%

Looks like you are lacking for any kind of preservatives so any batch you make should be small and last no longer than a week. Also make sure your beakers, mixers, spatulas, etc. are extremely clean before you make anything.

[Iaskedbetter]

I would second Marks observations here. You either don’t have enough emulsifier(s) or you do not have the correct blend of emulsifier(s).

If you haven’t estimated the required HLB for your oil phase, then that would be a good place to start. Also, if you still plan to use that ZnO dispersion, you’ll have to factor in the extra silicone from there as well (D5). 

[Iaskedbetter]

Unless there is a highly effective “SPF booster” in there I am missing, I don’t think you’re going to be able to achieve SPF 35 with that level of actives.

Looks like ~6% ZnO and ~1-1.3% TiO2.  Good rule of thumb for a very rough SPF prediction would be 0.7-1.0  SPF unit per 1.0% ZnO and 2.0-3.0 SPF units per 1.0% TiO2. 

Assuming of course you are using UV grades and not pigmentary grades.

[Iaskedbetter]

Bi-phase makeup removers are fairly popular.

http://www.healthspan.co.uk/products/bi-phase-eye-make-up-remover

I second @milliachemists assertion that syneresis is generally viewed as a negative formula attribute. There are far more formula types that are designed to perform as a uniform systems rather than 2 separate systems.

[Iaskedbetter]

Viscosity would be another good test for the sake of comparison.

@Robert can you elaborate a little bit on the Oil level test (how it works/how it is generally performed)? I haven’t heard of that one before and it seems very useful.

[Iaskedbetter]

You are looking for a good “cosmetic astringent”. “Astringents” are used to get that “tightening” or “tingling” sensation in cosmetic formulas. I’ve never used them myself, but that may help you in finding what you are looking for.

[Iaskedbetter]

I usually think of “emulsifiers” as molecules that are active at the water-oil interface. Materials like Cetyl alcohol, stearyl alcohol, cetearyl alcohol, etc. support emulsion stability typically by increasing steric hindrance and often times get lumped in as “emulsifiers” themselves (even though they are not active at the water-oil interface).

Also, @Belassi I’m not sure what kind of silicone you are using, but I’ve found that applying the HLB system to silicones can be pretty hit or miss. However, I have had more luck with low HLB emulsifiers than with high HLB one’s for dimethicone in particular.. 

[Iaskedbetter]

Eeesh. That’s quite the challenge. If you avoid chemistry definitions, you can really only get a very basic understanding of what those terms mean. 

I think the pivotal concept that cannot be avoided would be “charge” (or “electrical charge” but for simplicity’s sake, lets stick with “charge” for now). A molecule can either have a “charge” or not have a “charge”. If it does have a “charge” it is said to be “ionic“, and conversely if it does not have a “charge” it is said to be “non-ionic“.

Now within this broad definition of “charge” we are working with, there are two kinds. “Positive charge” and “negative charge”. If a molecule has a “positive charge” it is said to be “Cationic“. If a molecule has a “negative charge” it is said to be “Anionic“.

[Iaskedbetter]

@Perry That appears to be the most logical explanation. I imagine the cost for a prolonged legal battle for a small company would be crippling. Some (most?) probably don’t even employ a legal staff for situations like this. Larger companies almost certainly have the wherewithal - both from a monetary standpoint and an ethical standpoint - to combat these clowns.