[Pharma]

Dang, my notes said high HLB… re-looked it up and turns out, we’re both right (CLICK). Okay, you have a low HLB quality and that really should be fine with Tween 80.

I know what you mean but I don’t understand why it’s not working (and I was confused you didn’t understand me because you mentioned 15 minutes like I did but in a different context).

Polyglyceryl-4 oleate alone does work, no? It’s cold processable and should do really fine. I’m not sure if Tween 80, although liquid and usually cold processable, might require heating and mixing during cool-down like other PEGs do. Not that it’s a problem of preparation rather than incompatibility.

Oh shuuush, I just re-read your first post: 20% emulsifier and 80% oil? Really? You don’t need that much for an oil bath, that’s complete overkill and probably the issue of separation!

[Pharma]

As a rule of thumbs, use 1/10 anionic with regard to non-ionic. The non-ionic does most of the work, the negative charge simply adds to stability (negative charge of oil droplets causing repulsion and hence reduced coalescence).

[Pharma]

Do you know “Henleys Twentieth Century Book of Recipes, Formulas and Processes”?

A real treasure filled with old formulas and it’s readily available online as PDF (for free if you know where to look)!

[Pharma]

Is there a reason why you didn’t try adding a standard oil thickener/gellant?

[Pharma]

UsmanAli said:

How can we remove slippery and sticky feel after washing with face wash or hand wash…

If it’s caused by a quat, your best option is alcohol or acetone . Sorry for being a bit sarcastic but quats stick tightly to your skin and even as a molecularly thin film will feel slippery. Removing such trace amounts isn’t easy and your best bet is to use a product which doesn’t contain anything quat-related. Even some fatty alcohols and non-ionic detergents have this effect, though less pronounced. It’s a bit like a rinse aid in dishwasher detergents which ultimately stick to the dishes; super annoying if doing precision lab work. Rinsing with a solvent is the only feasible option other than using detergents free of such rinse aids in the first place.

[Pharma]

Conversion of °B seems to be not fully regulated but depends a bit on the author/country and is also temperature dependent. But it should be just minor differences and still give you a fair idea on what’s happening.

Let’s assume you were to use the following amounts in mM (for me, it’s simpler to calculate with that for defined molecules):

NaOH: 58 mM

KOH: 240 mM

Stearic acid: 180 mM

Water is in excess and glycerol doesn’t contribute to any reaction whereas coconut oil can not be calculated in mol but we’ll use saponification value afterwards.

For simplicity, we first react NaOH with stearic acid so we use it up completely. Then we use KOH to neutralise the remaining stearic acid. This leaves us with 118 mM excess KOH. Since saponification values are in mg alkali per g fat, I do a switch between % and g per 100 g product: In other words, 49,17% of the added KOH is left for saponification of coconut oil = 6.61% total weight KOH. 14.84 g (for 100g product) coconut oil requires ~3.8 g KOH for 100% saponification. In the end, you have 2.81% excess KOH or a very alkaline soap!

This excess might be a result of quality or conversion inaccuracy. I’d assume your recipe is for a fully saponified product and if I were you, I’d do the proper maths with your products for a perfect 100%. Depending on your requirements/options/visions, you might want to use a tick too much or not enough alkali as it’s common practice in soap making.

If you want to keep the same “feel” of your recipe, it’s a 20:80 ratio (on a molar basis) of NaOH/KOH or in other terms a 20:80 mixture of soda soap to potash soap (again, on a molecular basis). This allows for a simpler calculation with just one of the alkalis and you calculate the alkali ratio last. Given that weight differences between Na and K in a soap molecule are minor, mixing 20 parts of soda soap with 80 parts potash soap (on a weight basis this time!) should give a product fairly similar to what you’re looking for. It might be easier, case you do a hot process, to do a batch of soda and potash soap apart and mix them afterwards (by melting them together). This gives you more flexibility in finding the right consistency/foaming/etc. because you can successively add more of one or the other whereas mixing all in the beginning requires you to run an entire batch for every ratio you want to try .

Hope this helped!

[Pharma]

Don’t go by HLB requirement of the oil. Since you have no water there’s no point in considering it . Out of curiosity, what was the HLB you calculated and how much did you add to the oil? Polyglyceryl-4 oleate has a high HLB, no? Mixing that with Twen 80 is obviously too much hydrophilicity. But it just doesn’t sound right that sorbitan oleate and Tween 80 wouldn’t work… they’re supposed to work. Well, another demonstration that cosmetic chemistry is an empirical science and doesn’t care too much about theory.

[Pharma]

Jamjar said:

@Pharma thanks for the formula. I do know how to work out HLB but have found Stearic Acid particularly confusing. 

How would one balance the HLB when using a coemulsifier like Ceteareth 20 which has a high HLB? 

What is confusing about stearic acid? You don’t have to determine its HLB but simply look it up. The maths afterwards is the same for all.

What do you mean by balancing HLB? BTW HLB doesn’t care about high or low or co-emulsifier or primary or whatever definition we print on them. HLB is just numbers.

[Pharma]

Bill_Toge said:

you don’t - salts of stearic acid are ionic, and HLB is only relevant to non-ionic emulsifiers

Says how? Sure, with SLS & co. having apparent HLB values of 20-40 it doesn’t make much sense but salts of weaker fatty acids with HLB between 15 and 20 it does make sense depending on what you’re going to formulate.

[Pharma]

(primary emulsifier)/(primary + secondary emulsifier)*HLB primary emulsifier + (secondary emulsifier)/(primary + secondary emulsifier)*HLB secondary emulsifier = HLB of mixture. Primary and secondary emulsifier are in grams or alternatively weight-% of total emulsifier (i.e. % primary*HLB primary + % secondary*HLB secondary = final HLB).

HLB of stearates are around 18-20 depending on counter ion.

[Pharma]

Yup, that’s the job of PG, creating a water phase without water and it has a refractive index similar to oils which turns the droplets in an emulsion “invisible” (the emulsion is not white but transparent).

I guess there’s a small misunderstanding regarding stability: It’s not your product which only has to remain stable for 15 minutes but the 200-300 litres of hot water in your bathtub once you added your bath oil into it .

And you don’t need a o/w system. All you need is a transient emulsion in your bathtub, that’s the trick. A theoretical w/o emulsifier system will not form a w/o emulsion at a dilution of 1:>10’000 but a semi-stable o/w emulsion and that will do as long as the bath lasts, which is between 10 and 30 minutes, probably 1 hour if you feel like being a mermaid or don’t mind soaking in lukewarm water.

If you’re fixed on HLB values: go with an HLB between 7 and 9 (as an example: Eubos uses polyglyceryl-3 palmitate). That’s the range of “maybe w/o and maybe o/w”. This allows for easier solubilisation of the emulsifier (as pseudo-w/o) and an o/w emulsion in your bathtub.

Regarding cheap: You might want to add 10-20% octyldodecanol (Eutanol G). It helps keeping oils of different polarities together (or oils and emulsifiers) and, although not an emulsifier per se, it renders the oil easier to emulsify in your bathtub. The advantage is, that it’s not turning your oil opaque and it might make it more fluid depending on the oils you use. For example glyceryl stearate, which is used for the same effects, makes the oil more gel-like and imparts opacity. Another “oil binder” (dunno how a substance which helps mixing oils of different polarity is called, hence I call it unprofessionally “oil binder”) are ethylhexyl stearate (Cetiol 868) and related esters of branched chain alcohols with straight chain fatty acids. These, however, won’t show a benefit regarding easier dispersion of the oil in bath water and aren’t as effective in solubilising high HLB emulsifiers in oil. Or stick with alkyl benzoate 🙂 .

[Pharma]

Well, if you mix magnesium chloride and zinc oxide in water and the two would react, then you’d get magnesium hydroxide and zinc chloride, not zinc sulfate .

Nope, you’re correct, MgSO4 and ZnO don’t react. Just today, a sales rep visited and she said their product is with magnesium sulfate because magnesium chloride did cause itching and often had to be washed off after 5-10 minutes.

And yes, I’m a pharmacist. Maybe try out valerian first. A sack full over the baby muffles screaming very well and you don’t have to change diaper that often either! Seriously, I can feel with you and in such moments I’m happy that we settled with dogs instead of kids.

(Sorry, now I sound like an a***)

[Pharma]

You’re using something closer to detergents than emulsifiers. A high HLB detergent/emulsifier has a larger part of its molecule being water soluble than oil soluble. Hence, it would have to solubilise in itself which in pure oil means inverse micelles, a state it can not achieve.

Either you add a “water” phase (glycerol or the like might do as well) and create an “emulsion” or you use an oil soluble emulsifier. Which means something with an HLB of below 4 if only 1 emulsifier is used and to be on the super safe side (and get very re-fattening bath) or below ~8 if a combination of a high and a low HLB emulsifier is preferred (faster “milk” forming without stirring and probably even some foam).

I made a milk to oil cleanser with 1% Tween 20 (similar to polysorbate 80), 1.5% glyceryl monostearate, and 1.5% sorbitan monostearate in a mix of oils and paraffin and it didn’t separate but turns milky and just slightly bubbly (foam could be boosted easily with some tweaking, I’m sure). You certainly have mixed similar things with success: Their behaviour is similar to a bath oil. Not sure what a blooming bath oil is, though.

If you want to add only a high HLB emulsifier/surfactant: A D-phase might work or add so much emulsifier that you actually have oil-filled micelles swimming in a pool of emulsifier… a stupid thing, because that would be basically a shampoo without water. An oil bath doesn’t need to form a stable oil in water emulsion in your hot tub. An oil bath formula just needs to form an emulsion-like or milky state visually stable for 15-30, at most 60 minutes, depending on how long you’re soaking before the bath water, by then lukewarm, goes down the drain. Medicinal oil baths here in CH have an emulsion stability of about 5-15 minutes… not enough time for romance but they’re made for sick people with skin issues. One sales rep was even VERY proud that their product cracked the 10 (or was it 12?) minutes mark and I was like “Dude, what exactly does your R&D team do? Do they hire cause I’ve been dreaming of getting paid for doing nothing….” (I did only think that but temptation was nearly overwhelming :smiley: ).

[Pharma]

Thanks for trying/sharing! I wonder how it changes in the next days. Already great news (IMO) that pH is jumping to 6.

The pH those stripes indicate is only accurate (as accurate as they can manage) instants after wetting. Minutes later, even well before they dry, that value will change to whatever. It’s a bit like pregnancy tests .

ZnSO4? Did you add magnesium sulfate this time?

Regarding toddler: I hear Benadryl works wonders, on both, the parents and the baby. -> Sorry, don’t take that serious, I’m joking! Go with Valium instead… :smiley:

[Pharma]

Propositions by Wiki for lime :smiley: .

BTW it still might be an issue with low pH.

[Pharma]

Upps… I thought you added lime aka chalk and not essential lime oil!

Forget what I said (& can’t help you then, sorry) .

That’s the problem with colloquial language and the reason why INCI names and/or proper chemical/botanical names should be used.

[Pharma]

Chlorophyll is soluble in nearly everything and is available in special oil soluble grades .

Green “French” clay aka montmorillonite might be an option which helps to bring out green colouration?

BTW Adding titanium dioxide will inherently turn green hues lighter.

[Pharma]

Very often, methyl- and methylchloroisothiazolidinone are used for such products. Are they good antimicrobial agents? Probably not… Are they good antimicrobial agents? Yes, they are.

[Pharma]

And I “accidentally” replied in “Science” too .

Read there.

[Pharma]

99% chance that it’s due to the addition of lime. Why do you add lime and not sodium or potassium hydroxide to adjust pH? Apropos pH: low pH might be another issue… what is the actual pH of your formulations?

Green tea extract could, at elevated concentration, also pose a problem but I’d still assume that the culprit is lime.

[Pharma]

To my knowledge (which is in this regard over 10 years old): Nobody knows (knew) why or how. It was all speculation to the point where I didn’t really bought into it. At least, it’s a mix of several different factors playing a role.

Probably there’s new knowledge available… Hence, you pose a very good question here!

[Pharma]

tinas said:

I was sure silver ions is good for the skin - like treating acne and sore skin. So that is not true then? If I add 10% of the water phrase as silver iones ( and 90% water) - could that be effective as acne treatment? (I make my own silver water using a battery and pure silver rods.

A battery… what you get with that is a mixture of colloidal silver, silver ions and silver salt (if it works: a grey to dark colour tells you that it does).

For killing bacteria (and that’s about all silver does, except for potentially harmful stuff related to it being a heavy metal), all it takes are 10-20 ppm, probably less.

Could it be effective? According to FB and the like, silver is an organic, all natural antibiotic and miracle substance which imbues the user with magical powers and eternal life. Science says that it kills bacteria on contact (because it’s a heavy metal which reacts with proteins). In most applications, silver is inactivated by proteins.

[Pharma]

That’s what I

MarkBroussard said:

…The hexahydrate of Mg2+ (aq) can form hydronium ions … protonated water.  Since ions in solution are simply charge densities interacting with one another, the dissolved Cl ions will be attracted to the protons … that’s HCl.
…

^^ Exactly the point … if the contaminants do not affect pH, then it is not the contaminants causing the pH drop … it has to be some form of acid.

Jup, it will form oxonium ions but they do not form HCl since HCl is a stronger acid than magnesium hexahydrate. It’s just a mixture of H+ and Cl- and a bunch of other ions as well and not the strong mineral acid required to dissolve ZnO. Mg(H2O)6 is a very weak acid which only has pH drop in water like any other weak acid would. The reaction product of ZnO would be, since there is ample excess of water, Mg(H2O)6 and Zn hydroxides (forms are pH dependent). Since the original acid is not used up but simply acts as catalyst, hypothetically, all ZnO would turn into zinc hydroxides because there would be no neutralisation of the acid. It sounds much like a perpetual mobile machine. Anyway, according to your logic, zinc hydroxides will (and in an isolated model it really would) react with chloride ions to form ZnCl2. Alas, that would leave magnesium hydroxide, a fairly alkaline and poorly soluble product. But, since it has better solubility, it will back-react with zinc chloride to form again magnesium chloride and zinc errr…. hydroxide or oxide? What pH does in the mean time remains speculative. As you can see, it’s an equilibrium which is shifted to one side. The question is, which one. As an educated guess I’d say it’s heavily shifted to the original state (also because ZnO suspensions don’t really show alkalinity). Probably some of the zinc oxide degrades to neutralise pH but it’ll be not much because of exactly the same reasoning you mentioned with regard to stearic acid.

My guts still tell me that acidic magnesium chloride contains an excess HCl in the form of magnesium complexes. They are indeed very likely to react with ZnO but are also very likely to be just present in trace amounts. It doesn’t require much HCl to drop pH of an unbuffered solution.

@Zaf Try mixing some MgCl2, ZnO and water and see what happens! Would be very interesting! And don’t forget to regularly measure pH.

[Pharma]

Let me start breaking it down a little (more help from others will be needed):

Water: it’s just water.

Isoceteth-20: Solubiliser mostly for the essential oils. A more natural alternative might be polyglyceryl-10 laurate.

A lot of essential oils and menthol: Replace menthol with essential Japanese mint oil which consists of mostly (natural) menthol.

A lot of plant extracts: They may or may not show effects but they are natural.

Tocopheryl acetate: Likely doesn’t do anything. Replacing it with (natural) tocopherol could even result in increased formula stability (degradation-wise).

Glycerin: Maybe comes as part of one of the extracts? Likely too small quantity to add much effect. It’s natural, though.

Two polymers: Main “active” ingredients. May be replaced with natural polymers but likely to be less efficient/nice.

Distaryldimonium chloride: A Quat, the other main “active” ingredient. No natural alternative but so called ester-quats (such as Varisoft EQ 65 or Varisoft EQ 100) would at least be biodegradable and from renewable feedstock.

Disodium EDTA: Chelate, might be replaced by phytic acid or add more citric acid.

Phenoxyethanol & chlorphenesin: Preservatives. There are eco-friendly/sustainable and even natural alternatives available.

[Pharma]

I tried Dermofeel Viscolid, it works similar to other saturated oils/fats i.e. turns oil into something like vaseline (or more liquid at lower %). But in my trials, it renders, like other saturated triglyderides or waxes, the oil somewhat opaque. Probably a tick less but that might just be a biased observation.