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Neutralizing carbomers
I am making a lubricant product that will be used in the vagina. Vagina pH is 3.8-5.0 (generally).
I am using Ultrez 30 at 0.5%. What is the best course of action? Should I neutralize Ultrez 30 with NaOH at 0.5% which would bring my pH pass 5.0? At the end of the batch than adjust pH with a citric acid solution?
or
Could I just neutralize my Ultrez 30 till the pH is with my 3.8-5.0 range?
I am having to reformulate several formulas because the final pH range are above 7.
Thanks! -
25 Replies
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If you use Ultrez 30 at PH 5 you are likely to get instability in storage as the former is borderline unless you buffer but even then anticipate stability problems.Why not use a Simugel INS with xanthan gum-no ph worrries.?:
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@DRBOB@VERDIENT.BIZ
“If you use Ultrez 30 at PH 5 you are likely to get instability in storage as the former is borderline unless you buffer but even then anticipate stability problems.”
—so in the above example would I need to definitely pH 8.0 for stability? Ultrez 30 is suppose to work at lower pH per the vendor.
I don’t have a lot of room to be creative and use different chemicals. R&D on a shoe string budget make me very limited in my options.
“Why not use a Simugel INS with xanthan gum-no ph worrries.?:”
If you don’t mind explaining why wouldn’t there be any ph worries? I do have xanthan gum at my disposal. Is there anything else I can use besides Simugel INS?
Thank you for your input! -
Could I use Sepigel 305 in place of Simugel INS?
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yes you can use Sepigel 305 which is based on an amide (see INCI below) and stable over ph range of 3-10.Carbopols are acrylic acid terpolymers which have to to be neutralized above 5 to remain in solution to build viscosity and stabilize the emulsion. ;if ph drops in storage below 5 the Carbopol reverts to acid form again which drops out of solution causing loss in viscosity and destabilizes emulsion.
INCI Name:Polyacrylamide (and) C13-14 Isoparaffin (and) Laureth-7
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makes sense… I am trying a few lab batches before I go home… let you know next week what happens! thanks for the tip.
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My bad! I forgot to mention I need a “clear” product!
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changes things ! Can you get cellulosics like Natrasol 250HHR (hydroxyethyl cellulose) ? what else do you have in formula?
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@DRBOB@VERDIENT.BIZ
Thanks for answering me!
I am reformulating this…I have lots of Natrosol 250HHR. I have made a few changes from the original formula but this is what I am working with…water-63.3
carbopol Ultrez 30-0.2%
NaOh -0.5%
Hydrovance - 1.5%
Covafresh IV -1.0%
water -22.3%
carboxymethyl cellulose -0.09%
Propanediol -7%
Extracts (chamomile, aloe, ginseng) - 0.009%
Ascrobic acid - 0.003%
preservative - 1.0%
DC-3901-2.0% -
Rather than patch up some pre-existing mix, you may be far better off starting afresh - without the fairy dust (in this instance any ingredient below 0.1%).
I have always found that Hydrovance is very difficult to stabilise and I don’t think that, at that level, it is doing much good.
Another thing - are you sure that the rheology of Carbopol type materials is what you want? OK, they are fine for uses where breakdown of their gel structure is of little or no importance but these materials very quickly lose viscosity when subjected to more than minimal shear and, in the presence of ionic substances (such as might be found in the vagina - lactic acid, salt etc) a competely liquid product can be formed.
I have noted previously that a lower viscosity grade of Natrosol may be advantageous, if that is what you decide to go with. It will certainly be more stable than carbomers.
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@johnb
the final product is a viscous gel that doesn’t readily flow but can be squeezed out of the container. I am changing the ultrez 30 to Natrosol. And do a pH adjustment to 4-5 with 50%citric acid solution at the end.I have ordered the other grade of Natrosol…enroute as we speak. I am learning so much from doing all the lab batches and this site. Thanks so much!
I was going to take out the hydrovance out what do you suggest as a moisturizer? I was going to keep the DC-3901 to help with the slip and feel.
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Now you’re rid of Carbopol there are a number of moisturisers that would be compatible. What I suggest is a lactic acid/lactate combination - lactate being sodium or ammonium lactate. You adjust the ratio of the two in order to achieve the desired pH. The best thing about lactic/lactate is that it is a normal component of the vaginal secretions.
In addition, a lactate buffer/moisturiser will offer the best compatibility with the menthyl lactate in the Covafresh IV - that is if you feel this ingredient is necessary. I am not blessed with a vagina but I shudder (figuratively) at the thought of an icy cold body cavity - the figurative qualification could well become real in actual users.
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Just use glycerin.Do you do the cheek test for pseudoplasticity?
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Are you really going to put CovaFresh in a product designed to be used IN the vagina? I’d re-think that … I mean, what’s the purpose?
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Glycerin is not a good choice for a product to be used in the vagina … can promote yeast infections … many women will avoid a lubricant that contains glycerin.
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Re-reading my post above, I can see a cause of confusion.
What I suggest is a lactic acid/lactate combination - lactate being
sodium or ammonium lactate. You adjust the ratio of the two in order to
achieve the desired pH.What I mean there is adjust the ratio of lactic acid and lactate, not the two lactate salts.
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I included Lactic Acid in a vaginal lubricant development project and it was ultimately rejected by the client and it caused a slight burning when used. It sounds like a good idea given the vaginal environment, but in practice did not produce acceptable results. Sodium Lactate alone as a moisturizer did perform well.
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What I meant in using lactic acid was have that as the pH adjuster if necessary.
I am still concerned, as is Mark, about the advisability of menthyl lactate in an intra-vaginal product. Are there specific claims/reasons for its inclusion? Are we getting involved in “kinky” products here?
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@MarkBroussard
I must commend you on your dedication to answer my question at 3am!
The earlier formula is a cooling lube from a previous chemist and has to be revamped. The product is one of the our best sellers! I have to take out glycerin, PG, parabens, to make it nicer to the vagina.
Covafresh IV is being used as the cooling agent at 1.2%. Suggested use is between 2%-10%.
This is my formulation tell me what you think:
Water-66%
Natrosol 250 HHr - 1.20%
NaOH (10% soln) - 0.05
Propanediol - 26.5%
Covafresh IV - 1.2%
Panthenol Liquid - 0.01%
Chamomile Extract - 0.01%
Aloe Vera Extract - 0.01%
Water - 2%
Potassium Sorbate - 0.2%
Phenoxyethanol -1.0%
citric acid 50% soln - 0.1%
spheres(decoration) - 1% -
I don’t think the use of either methyl lactate or lactic acid is advisable for a vaginal product, one cools and the other irritates/stings.
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What is the purpose of the NaOH now that you have removed the Carbomer? I don’t see the point of the citric acid either.
What is the constitution of the spheres? If plastic, have a rethink. They are to be banned (if not already).
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citric acid is obviously for Ph? Agree with John as why the need for decorative spheres which if plastic can only be deleterious to the product.Can you tell us reason for cooing gel?
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most of the formulations for this company have products for the vagina that are pH 6 and above. Vagina pH is normally 3.8-5.0. I am staying with in this range for all of my formulations.
The beads readily dissolve when rubbed. The purpose is just like in cosmetics…. to add something different to a product line and see if it sells. If warming lubes doesn’t work why not try a cooling effect. Somebody likes the beads b/c it is one of our best sellers. People like pretty lubes too. What ever works to achieve gratification sexually?
I am not even sure if the concentration of covafresh is high enough to produce an effect at 1.2%
@johnb
I noticed with the natrosol/water premix the pH is normally around 6.3. I neutralize it to above ph 8 to make it more viscous. The lubes I am making should have some “body” and be not be thin/runny. Citric acid at the end is use to bring down to 4.0-5.0. -
I am still of the opinion that lactic acid would be a better choice over citric acid. The amount necessary to lower the pH will be extremely small and I very much doubt that the quantity it would cause the irritation that seems to be of so much concern to others here.
After all, lactic acid is a normal component of the vaginal secretions. I don’t think the same could be said about citric acid.
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Lactic acid is a natural by product of energy expenditure ie metabolism and when produced by the body via exercising /muscle contractions and so on is released via body fluids and as such can be viewed as an inside___outside process which although chemically similar to added lactic acid, which is an outside—inside process, appears to behave differently as the latter promotes irritation while the former does not in so far as we know.
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That’s correct @DRBOB@VERDIENT.BIZ. I can tell you from experience having tried adding Lactic Acid to a vaginal lubricant formulation … it simply irritates what is very sensitive skin within the vagina. It is not an acceptable ingredient for vaginal lubricant products.
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