[ccchem]

I got this from an Italian place a few weeks ago. There’s no scent right out the bottle. I am using it in a fragrance-free cream, in combination with other esters and d350. Nothing stands out in the final product.

[ccchem]

Look into cetrimonium chloride, it’s a great detangler and also reduces static. You can use it up to 0.25% in leave on products. Cetrimonium chloride is typically purchased as an aqueous solution with approximately 30% concentration, so you would have to consider that when determining the correct maximum amount for your formula.

Guar hydroxypropyltrimonium chloride will help with the slip from 0.01 to 0.15% in leave in products.

[ccchem]

I have had success with glycol content of around 25-35%. I have used both 1, 3 propanediol and propylene glycol with a final pH of 3.8.

@MarkBroussard I finally got my hands on some methylpropanediol and butylene glycol. What ratio would you recommend for this combination of glycols? I’m not sure if this is normal but the butylene glycol has a strong alcohol scent, and I would prefer to minimize what comes through the final product. I am aiming for stability at pH 3.2 - 3.6.

[ccchem]

@Abdullah thank you. Yes, this is what the supplier recommended. I am now wondering - if this is indeed due to the presence of iron, will the long-term stability be affected?

[ccchem]

@MarkBroussard @chemicalmatt @ngarayeva001

Thank you very much for your suggestions. I was able to resolve the clouding issue. 2 months later, the sample is still clear.

In my quest to try out different solvents I found 1,3 propanediol from a local supplier. However, during my experiment the propanediol turned reddish purple as soon as I added SA to it. My research tells me that SA will form a red/purple complex in the presence of iron. Has any of you experienced this?

[ccchem]

@MarkBroussard Thank you for your comment. Unfortunately, I do not have Cocamidopropyl Dimethylamine on hand, so the polysorbate will have to do for now. Apart from Cocamidopropyl Dimethylamine, are there any others you recommend - that are better than Polysorbate 20 or 80?

Thanks for the tip on Sodium Citrate and preservation, I’ll go with the citrate alone and switch to Phenoxyethanol/EHG.

On the glycols - I was really hoping to get good stability at <30% input. Looks like there’s no way around this!

I’ll be back with results once I test another sample with these tips.

Thank you all

[ccchem]

Thank you all for your responses!

@chemicalmatt the polysorbate 20 is in there for two reasons; 1. To lower surface tension to make the solution more readily wetten skin, and 2. As @ngarayeva001 mentions to reduce the chance of recrystallization.

@toketsu, yes that’s right! that’s the approach I was going for. 

An update on how the samples are looking - I increased the pH of both samples to closer to 4. Sample 1 with 25% glycols is clearer but still a little cloudy, pH 3.8. Sample 2 with 30% glycols is completely clear, I actually got this one to pH 4.1.

I am going to do two more trials - one with sodium citrate and the other with t.edta . I’m trying to get my hands on some butylene glycol so that I can use propylene/butylene mix.

@ngarayeva001 how much polysorbate do you recommend? I would like to minimize ingredients as much as possible. Also, what’s your ideal pH for stability and do you use NaOH as a buffer?

[ccchem]

GeorgeBenson said:

I make a shampoo with the same surfactants. it’s a very nice combo. Salt is not going to help you here, you will have to use a thickener of some kind, as you have found out. Where do you live? 

ketchito said:

@ccchem PEG 150 Pentaerythrityl Tetrastearate is part of Crothix Liquid, which can be easily found. You could also try with Versathix or Genapol LT. Also, you can avoid polymers and add Cocamide DEA (or MIPA or MEA), and increase your Betaine. You’ll have a better salt response.Ichlas said:

 Thanks for sharing this. I was hoping for a cheaper option than crothix and polymers. I will definitely give the Cocamide DEA a try. 
I am doing a few more experiments and will be back with feedback. Thank you!

Ichlas said:

Take out salt, use Acrylates Polymer/Cellulose/Gum or any other polymeric thickener

Thanks for this suggestion. Unfortunately, these are a bit difficult to find for me due to the hefty courier and import charges!

[ccchem]

evchem2 said:

You can try deoplex from carrubba for odor masking

Thank you! I’ll definitely look into this!

[ccchem]

justaerin said:

Used in larger proportion it can change how a fragrance is perceived by altering the rate of evaporation in alcohol-based perfumes.

Thank you for sharing this. What would you define as a “larger proportion”?

[ccchem]

Pattsi said:

@ccchem - It’s not as simple as deeper is better.
There’s issue with ensuring consumer safety.
And then even if you can manage to go to Stratum Basale, how will you determine it not cross through to Dermis.

I understand this. Thanks

[ccchem]

suswang8 said:

@ccchem:
I would be interested in knowing what you learned about these two topics:

• Type of formulation; Polymeric, O/W emulsions, solution, etc.
• Choice of emulsifier

Unless I am mistaken, the only way one knows for certain what is penetrating the skin is through tests on cadaver skin or some sort of equivalent model, but this is quite a “black box” of a topic.  For example, I stumbled upon one recent journal article that was outside my comprehension but seemed to suggest that liposomes do not actually deliver ingredients through the epidermis, as many would have us believe.

@suswang8 You’re right - it certainly is a black box. That’s why I’m calling on people’s experience here.

In this example the researchers assessed the influence of the formulation type in the delivery of Glycolic acid and Glycerol. They compared an aqueous solution, a 30% propylene glycol (PG) aqueous solution, an oil-in-water (O/W) emulsion, a water-in-oil (W/O) emulsion, and two nonionic liposomal systems. You can read more about it here

For the choice of the emulsifier read more here and here (page 9)

Let me know what you think.

[ccchem]

vitalys said:

@ccchem I would have added to the list you posted the following aspects:
- Molecular weight of an active
- Hydrophilicity/ Lipophilicity of an active substance
- Condition of the Stratum Corneum and its barrier system
- Understanding what an active is going to do when it reaches a particular layer in the SC/the mode of action/biochemical transformation or utilization
All these factors along with those that you have mentioned above will have an impact on penetration and the delivery. 
I can not tell any rule of thumb, because the system of the delivery will highly depend on a particular substance that you want to include in your formula. 
For instance, keratolytic formulations with Urea are going to be more efficient in the presence of acids and polyols.

@vitalys Thank you so much for this response! This is the kind of information I was looking for. I have noticed keratolytic formulations with Urea usually include Salicylic acid - thanks for this nugget.

[ccchem]

Pattsi said:

watch Perry and Belinda

Latest Q&A session >>>>

Thanks for your suggestion. I actually attended this Q&A

[ccchem]

Thank you very much for this feedback, it’s very helpful. I did not pay for the formula so there’s a possibility that they did not disclose the complete formula.

[ccchem]

Most likely due to different melting points of fatty acids in the butters. If this is the case, you can fix it by melting your balm - making sure the granules are completely melted, and then freezing it. The point is to cool it very fast. This always works when I have grainy butters. Hope this helps

[ccchem]

@sweetflakes I am not sure what caused the clouding but with both versions, increasing the pH closer to 4 resolved it. Both of them are still stable today, almost 6 months later.

@Trng1122 I ended up switching solvents to methylpropanediol and butylene glycol and I have a stable formula at pH <3.2-3.5. I dropped the citrate and a maintained T.EDTA.

@PhD.Pharm.EM I tried it with propylene glycol only, but it left an unsightly shiny appearance and a somewhat tacky feel. I still use some heat (about 40-50c) to reduce stirring time when dissolving the SA.

[ccchem]

This worked, thank you!

[ccchem]

@suswang8 apologies for the late response. I was having trouble logging in. I used that temperature based on advice from this board. I didn’t go as high on my last sample about 8 weeks ago, I got it to around 60c I think, and my sample is still stable. What’s the lowest temperature have you used to get a stable SA toner?