[Robert]

PhilGeis said:

To pharma’s excellent post - I’ve limited experience with phytic acid, esp. titrating levels.  It does work.  Agree re. cap hydroxamic acid - like pyrithione (ZPT - another hydroxamic acid) it might have some efficacy vs fungi but nothing for bacteria.
Chelate free systems do work - my experience in these includes ironically antidandruff ZPT products (EDTA screws up ZPT), products with some physical aspect (gels) and shampoos that added divalent cations for foam characteristic.  
I try to design the best system and my bias in that is always EDTA.

you mean even some products have zinc oxide can be interrupted by EDTA?
Also on the same issue we can not add EDTA in selenium Disulfide Antidandruff shampoo? 

[Robert]

Pharma said:

Robert said:

Regard Azelaic acid do you think suspended particles will be effective, I tried glycols to dissolve and then add it to the cream base but always same results grainy and sandy cream

Skinoren, a pharmaceutical product, contains micronized azelaic acid and they showed skin resorption… a not so great one, honestly… Anyway, micronized particles do slowly dissolve on skin, then penetrate skin leaving the solvent ’empty’ and ready to dissolve some more crystals and so on. To obtain such sink conditions, the trick is to have an okayish solubility in the carrier (cream/gel) but keep it lower than solubility in skin . Alternatively, use a solvent which penetrates skin easily but that will require the use of an excess activce and result in lots of active ingredient remaining on skin (likely the case with Skinoren).

Thank you I appreciate your comment a lot, I am already using micronized pure Azailic acid from Corum, I mix 10% butylene glycol with 10% Azailic acid and disperse it in a cream base, I hope it can give reasonable effect 

[Robert]

Pharma said:

Phytate is a polyelectrolyte, worse than citric acid (theoretical 12 negative charges!). GLDA and EDTA just carry up to four… still, if you’re encountering issues with salting out effects try using ingredients with a low amount of trace metals so you can safely use the bare minimum of a chelate. As alternatives, caprylyl hydroxymic acid might work (personally, I don’t trust that guy) and, theoretically, nordihydroguaiaretic acid might too. Depending on the ingredients and the overall preservative system, you might get away without using any chelates at all. Maybe @PhilGeis has some experience with atypical and/or nonionic/monoionic chelates?

Regarding azelaic acid: if it isn’t micronised, then a suspension will easily feel sandy/grainy (and possibly irritating where there are too large crystals sitting and dissolving on the skin). Heating can speed up dissolution but you should only add as much azelaic acid as your system can dissolve at room temp (better even slightly below that), else it will always crystallise out once cooled down (because solubility of it increases with increasing temperature and vice versa). Also, recrystallisation will easily lead to even larger crystal needles than before.

50°F? Are you an Inuit? Cause for all others, 50°F (=10°C) isn’t considered heating but cooling :smiley: !

To my current knowledge and experience, azelaic acid can not be properly dissolved in anything acceptable at an effective concentration unless you want to go anhydrous and/or gooey/sticky. You’ll likely have to come to terms with a life full of compromises.

As mentioned in another thread on salicylic acid, neutralising such an acid will render it water soluble but also utterly useless and ineffective (though you can still claim ‘contains XYZ%’).

Regard Azelaic acid do you think suspended particles will be effective, I tried glycols to dissolve and then add it to the cream base but always same results grainy and sandy cream

[Robert]

I have the same problem, I solubilize it at proylen glycol with heating and it turns transparent liquid and include it in cream but after cooling the day later it recrystalized again, should we just suspend the powder in creams? by this way I am not sure it will be effective on skin

[Robert]

ketchito said:

@Robert It seems there is a problem with your emulsifying system, but it’d be better if you write down your formula.

it is a general problem there is no specific formula 

[Robert]

@Abdullah @ketchito 
Do not you think that anionic surfactants lower than 9% as an active material is un acceptable as a shampoo?
Also 1501 will definitely separated, 
as a suggestion i am adding cetrimonium chloride combined with SLES in the shampoo some how is good on hair but not perfect, I am disappointed with shampoos becuase I tried everything to make shampoo for soft and smooth effect on hair but all the time failed

waiting any suggestion