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Could I be adding too much citric acid to reduce PH
HiApologies if this question has been raised before, I have looked at previous comments but could not find an answers.I am formulating a day cream, and adding citric acid to reduce the pH down but I am worried I am using too much citric acid, all previous comments suggest using citric acid at 0.5% but I am having to use 1.35% to reduce the ph to 6.35 - Ideally I would like the day cream to have a pH closer to 5.5. but reluctant to use more citric acid - I have calibrated my pH meter (twice to make sure it was reading correctly) - my formula is below. Any suggestions would be greatly appreciated. ThanksWaterRice Bran Oil 4Chia Seed Oil 3Grapeseed Oil 4Shea butter 2Coco-caprylate 3Cetearyl Glucoside 3GF e-wax 3Cetyl Alcohol 2Glycerine 2Sodium Lactate 2Vitamin B3 4Glucosamine Powder 2Eco silk 3Honeyquat 2.5Zinc Oxide 2Hydrolyzed Oat Protein 1Bearberry in Propylene Glycol 1Licorice Root Extract 1Epidermis & Sebum Balancer 1GF Preserve 1Hyaluronic Acid 0.01Citric acid ?Allantoin Powder 0.5Xanthum gum 0.3Vitamin E 0.2sweet orange (t) x 4 drop 0.25lavender 0.2Rose Geranium 0.2Neroli 0.16Roman Chamomile 0.04 -
27 Replies
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What do you think is wrong with adding more than 0.5% Citric Acid?
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You could try a different acid like Lactic Acid. Or even Hydrochloric acid.
What is the pH of the formula without any Citric Acid? -
Hi Bob,
adding Citric at 1.35% affects the viscosity of my cream, it becomes quite stringyadding more than 0.5% might cause sun sensitivity, and would I need to label my products accordinglyI can’t find any info to suggest that adding more than 0.5% is ok, so adding 1.35% is ok, all I can find suggests reducing ph using citric acid. -
Hi Perry
The starting pH is 7.96,I have also used lactic acid but used a high % too, and this altered the viscosity in the same way as using citric acid. -
I agree with @Perry. Use a stronger acid, like HCl. Or, you could reduce the amount of basic material in your formula.
Also, you are not using enough suspending agent to keep 2% Zinc Oxide stable for very long. You’re going to need something with a higher yield value than Xanthan Gum.Last but not least, there’s a bunch of “active” ingredients in there at extremely high levels that are unnecessarily complicating your formulating efforts. Get rid of them all, make a stable emulsion at the pH you want, then you can try adding them back (preferably one at a time, so you can isolate the effect thy have on stability) -
Thanks Bob for your comments, would you mind if I ask a few questions on issues you raised with my formulation:
you suggest removing “amount of basic material” please could you clarify what you mean as “base” should I lower the %Re zinc, what would you suggest I use as a suspending agent (I am trying to keep my formula as “natural” as possibleRe active materials - do you mean the Vit B3 and Glucosamine? what % levels would you suggest?Re the plant extract, I can add them at the end at your suggestion, but the B3 and glucosamine are added to heated water phase so difficult to add them at the end.I appreciate you are busy but would be very grateful of your comments.Thanks -
I think the sodium lactate is the cause of you problems with pH reduction. Do you really need it at 2%? Sodium lactate comes from a strong base and a weak acid, so when dissolved in water will give you a basic pH.
Also you have protein, which may be buffering your formula and making it even more difficult to reduce the pH. -
The sodium lactate may be involved in a replacement reaction producing sodium citrate.
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Thank you for all your comments, I am very “amateur” so your responses have been very helpful, I might have sorted it out by:
removing Sodium Lactate - having read from other posts that it could be the problemreplaced sodium lactate with panthenol at 1% and increased glycerin to 3% (no tackiness felt)replaced citric with lactic acid at 1.1% I got the pH down to 6 - I read another post that a formula with zinc should not go below pH 6 as this could cause the zinc to drift. I am ok with a pH at 6.Increased Cetyl Alcohol to 3% to help with the Zinc suspension and have reduced the zinc to 1% and dispersed in the Eco-silk (Isoamyl Laurate, Isoamyl Cocoate) before homgenzing - seems to be ok. -
Building on what Bob said the following ingredients are likely superfluous and could be significantly reduced or removed without any significant impact on your formula.
Vitamin B3Glucosamine PowderEco silkHoneyquatHydrolyzed Oat ProteinBearberryLicorice Root ExtractEpidermis & Sebum BalancerHyaluronic AcidAllantoin PowderVitamin Esweet orange (t) x 4 droplavenderRose GeraniumNeroliRoman Chamomile -
I have to agree. I see these ambitious ingredient lists all the time in Product Development. They almost always get revisited once the pricing occurs.
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@Perry although I partly agree and know what your point is I think that at the levels B3 and some other ingredients are used here I don’t think they have no effect- on the contrary - they contribute to a large part of the formulation properties -another question is - do we need this? probably not - so in this case - I would start from scratch and not trying to get the pH right. formulating is a bit like cooking - you can’t just put a lot of good ingredients together and hope it will taste good! better nice & easy adding ingredients one by one and testing - feeling-that is how you make a good recipe!
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I agree that many ingredients in the formula aren’t necessary and are in a amount much higher than the usual. But 4% of niacinamide +2% glucosamine is a interesting combination:
Reduction in the appearance of facial hyperpigmentation after use of moisturizers with a combination of topicalniacinamide and N-acetyl glucosamine: results of a randomized, double-blind, vehicle-controlled trial.
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@David - of course you are correct and removing/reducing all the ingredients I said could significantly change aspects of the formula.
I just think it is incredibly difficult to demonstrate a difference with and without an active in the lab and even more difficult for a consumer to notice any difference. Formulators should limit themselves to things in which they can prove an effect.My philosophy is this…If you can’t show a consumer perceptible difference between when an ingredient is present or absent then you should only use the ingredient at claims levels (0.1% or less).When you have over a dozen “active” ingredients the chances of you being able to show a difference with the removal of half of them or more are slim to none. -
@David and @Perry,
I think that there’s an argument from a technical standpoint here as well. None of the ingredients Perry listed will enhance stability. Since we are trying to solve a technical/stability problem, I think it’s usually a good approach to strip the formula down to the ingredients that are essential to making a stable product, make sure it works and that it fits the parameters you’re after, and only then evaluate each supposed “active” ingredient separately, and in combination with the others.Additionally, there are a lot of very expensive ingredients at high levels in the formula @juliap3 listed. Even if the formula is just for personal use, I think it makes sense to evaluate their use levels to keep from wasting money. -
Again, many thanks for time on this formula, I have revisted this formula and have removed a few of the ingredients but have kept some too - please don’t shoot me from above.. but wanted to keep some of the actives - the cream has a lovely feel, it appears stable will put it through a freeze / thaw to double check (I don’t have a lab to do anything too specific)Vitamin B3 + Glucosamine Powder - Bulkactives have reasearch to suggest this is a good combination and have read other studies too.Eco silk (a natural silicone replacement - it does give a very nice feel and in combination with coco-caprylate gives a very smooth silcone feel to the product)Honeyquat - have removed / Hydrolyzed Oat Protein - I am might remove this - supposed to provide film forming properties?? not sure if it does at 1% / Bearberry & -Licorice Root Extract have reduced - have read that it can provide “skin brightening & lightening ” properties - more for label appeal I think.Epidermis & Sebum Balancer - studies have suggested that it is good for sebum balancing (again good label appeal) / Hyaluronic Acid - have removed / Allantoin Powder - have kept / Vitamin E - have kept - antioxidant at 0.1%sweet orange + lavender + Rose Geranium + Neroli + Roman Chamomile - fragrance and it smells divine!!
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It’s definitely your 2% Zinc Oxide that raises pH, but it will also protects against AHA induced photosensitivity at a ~1:1 ratio.
I agree with @Bobzchemist s strategy of building your formula from the ground up, particularly if you’re having stability issues.
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It would appear you are trying to create a moisturizing day cream with skin brightening properties. If that is your objective, cut out all of the ingredients you have in there that do not directly contribute to that objective.
KISS (Keep It Simple Stupid) is the best approach while you are still learning how to formulate.
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This thread dates back to June 2015.
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Oh! … someone’s got too much time on their hands digging up old threads. This has been happening a lot lately
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I do have the ability to close off old threads but if the comments are still relevant then I don’t see a problem with it. Maybe other people see it differently?
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@Perry:
I think the issue is more relevant to the fact that you spend time answering questions to help someone out only to later learn the the OP who was looking for help, was seeking advice over a year ago and the issue they were trying to resolve is probably no longer relevant.
If someone is going to resurrect an old thread, and that someone is not the OP, it would be nice if whomever is resurrecting the old thread made note of that. But, I guess I’ll just start looking at the dates before I spend time offering advice that may no longer be relevant to the OP.
It would be better if whomever resurrects these old threads, just posted a new thread if they want to further discuss a technical topic.
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I’m going to try out a new plugin that will warn people with a big red box when they are responding to a really old post. Maybe that will help alleviate the problem.
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Apart from the antiquity of the thread, I should have pointed out that the recent response from Zink has no relevance whatsoever to the the original enquiry.
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@johnb no it does, zinc oxide will raise pH towards 7 and it’s worth pointing out as the goal was to lower pH of the formula and nobody had mentioned this.
Otherwise I was aware it was an old thread, but threads here serve as useful resources for others who find them through google (as I did) and work as wiki pages in a sense.
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