Home Cosmetic Science Talk Formulating General Dishwashing liquid is too acidic

  • Dishwashing liquid is too acidic

    Posted by Stephanara on March 14, 2022 at 10:05 am

    Good day everyone. I am glad to be in this forum. Thanks to Perry for accepting my application. 
    I have been working on formulating dishwashing liquid, i can up with this formulation which gave me, desired viscosity although not too transparent..But my challenge is when I finished the preparation, my son said” mum, I love this your liquid but it’s hurting my hands” I did a pH test on it, behold the reading was around 2-3. I checked the commonest one in the market, the pH was around 5. 
    LABSA= 16.4%
    SLES =16.4%
    Magnesium sulfate= 1.3%
    Water= 65.9%
    Please kindly help look into the above formulation and make necessary corrections. Thank you all

    Stephanara replied 2 years, 6 months ago 5 Members · 24 Replies
  • 24 Replies
  • Chemist77

    Member
    March 14, 2022 at 11:31 am

    You need an alkali like a sodium hydroxide to neutralize the acid to form a soap. Adjust the pH around 7 & and above, should be fine. 

  • Abdullah

    Member
    March 14, 2022 at 12:44 pm

    Agree with @Chemist77 + 16% labsa will not be very gentle to hands when you are washing your hands everyday for several minutes. 

  • ketchito

    Member
    March 14, 2022 at 12:57 pm

    @Stephanara After adding sodium hydroxide, check for any instability (put a sample in the fridge). I think you’re using a bit too much salt for that level of LABSA, and that ingredient is a salt-phobe, so to speak.

  • PhilGeis

    Member
    March 14, 2022 at 1:04 pm

    You’ll not form a soap per se - but dishwashing detergents are typically alkaline.  Suggest adjustment to ~ 8-9 with NaOH.   You might also consider a preservative.  Look at Dawn https://dawn-dish.com/en-us/how-to/what-dawn-is-made-of-ingredients
    Why mag sulfate?   for viscosity adjustment?  

  • Stephanara

    Member
    March 14, 2022 at 4:38 pm

    Chemist77 said:

    You need an alkali like a sodium hydroxide to neutralize the acid to form a soap. Adjust the pH around 7 & and above, should be fine. 

    Thanks @Chemist77 , will do that ASAP and give the feedback

  • Stephanara

    Member
    March 14, 2022 at 4:44 pm

    Abdullah said:

    Agree with @Chemist77 + 16% labsa will not be very gentle to hands when you are washing your hands everyday for several minutes. 

    Thanks @Abdullah. You suggest I should reduce the LABSA or I should just go ahead and neutralize as suggested by @ chemist77 while maintaining the formulation

  • Stephanara

    Member
    March 14, 2022 at 4:46 pm

    ketchito said:

    @Stephanara After adding sodium hydroxide, check for any instability (put a sample in the fridge). I think you’re using a bit too much salt for that level of LABSA, and that ingredient is a salt-phobe, so to speak.

    Thanks @Ketchito. Will do as you advised
     But what should I watch out for and what percentage of salt do you think I should try out

  • Abdullah

    Member
    March 14, 2022 at 4:50 pm

    I would say remove it

  • Stephanara

    Member
    March 14, 2022 at 4:52 pm

    PhilGeis said:

    You’ll not form a soap per se - but dishwashing detergents are typically alkaline.  Suggest adjustment to ~ 8-9 with NaOH.   You might also consider a preservative.  Look at Dawn https://dawn-dish.com/en-us/how-to/what-dawn-is-made-of-ingredients
    Why mag sulfate?   for viscosity adjustment?  

    Thanks @ PhilGeis. Ok. Suggesting I should adjust to between 8&9. As per preservative, I have been on the look out to see an acceptable by one that is readily available. Going to check the link you posted right away. Thanks so much

  • Stephanara

    Member
    March 14, 2022 at 4:55 pm

    PhilGeis said:

    You’ll not form a soap per se - but dishwashing detergents are typically alkaline.  Suggest adjustment to ~ 8-9 with NaOH.   You might also consider a preservative.  Look at Dawn https://dawn-dish.com/en-us/how-to/what-dawn-is-made-of-ingredients
    Why mag sulfate?   for viscosity adjustment?  

    Thanks @ PhilGeis. Ok. Suggesting I should adjust to between 8&9. As per preservative, I have been on the look out to see an acceptable by one that is readily available. Going to check the link you posted right away. Thanks so much

    Lest  I forget, I added the magnesium sulfate to adjust the viscosity

  • PhilGeis

    Member
    March 14, 2022 at 5:41 pm

    Dawn uses isothiazolinone and phenoxyethanol - with the apparent head fake that the latter is “solvent.” 

    Viscosity - would NaCl work ?  Might be cheaper  and less prone to soap formation with food fatty acids

  • Stephanara

    Member
    March 14, 2022 at 7:11 pm

    PhilGeis said:

    Dawn uses isothiazolinone and phenoxyethanol - with the apparent head fake that the latter is “solvent.” 

    Viscosity - would NaCl work ?  Might be cheaper  and less prone to soap formation with food fatty acids

    Thank you @ PhilGeis. I have gone through the Dawn’s formulation sheet at the attached link. The two reagents are not readily available. Do you think EDTA can suffice?

    Yes, I have tried NaCl before and it worked, but I observed it impaired the stability of the product

  • PhilGeis

    Member
    March 14, 2022 at 7:34 pm

    EDTA won’t work - tho’ a builder would be a good idea for cleaning.  It’s just a booster to preservative efficacy.    Your objective for household products is to make them clean - unlike cosmetics for which micro safety in use is an issue.
    Can you heat (pasteurize) product as final manuf step?

  • Stephanara

    Member
    March 14, 2022 at 7:53 pm

    PhilGeis said:

    EDTA won’t work - tho’ a builder would be a good idea for cleaning.  It’s just a booster to preservative efficacy.    Your objective for household products is to make them clean - unlike cosmetics for which micro safety in use is an issue.
    Can you heat (pasteurize) product as final manuf step?

    I appreciate your inputs and suggestions @ PhilGeis. I will make a trial as per the pasteurization

  • ketchito

    Member
    March 15, 2022 at 12:35 pm

    ketchito said:

    @Stephanara After adding sodium hydroxide, check for any instability (put a sample in the fridge). I think you’re using a bit too much salt for that level of LABSA, and that ingredient is a salt-phobe, so to speak.

    Thanks @Ketchito. Will do as you advised
     But what should I watch out for and what percentage of salt do you think I should try out

    If you put a sample in the fridg, the product should remail clear. If on the contrary it starts getting turbid, and then this turbidity settles, that’s probably your sulfonate salting out (you’ll notice it’s quite some amount of material that settled at the bottom).

  • Stephanara

    Member
    March 15, 2022 at 5:40 pm

    ketchito said:

    ketchito said:

    @Stephanara After adding sodium hydroxide, check for any instability (put a sample in the fridge). I think you’re using a bit too much salt for that level of LABSA, and that ingredient is a salt-phobe, so to speak.

    Thanks @Ketchito. Will do as you advised
     But what should I watch out for and what percentage of salt do you think I should try out

    If you put a sample in the fridg, the product should remail clear. If on the contrary it starts getting turbid, and then this turbidity settles, that’s probably your sulfonate salting out (you’ll notice it’s quite some amount of material that settled at the bottom).

    Thanks @@ketchito. So thoughtful of you to have followed up. I have actually neutralized with sodium hydroxide as advised yesterday, I will put in the fridge right away and observe

  • PhilGeis

    Member
    March 15, 2022 at 8:02 pm

    btw - NaOH and Mg sulfate will likely precipitate some Mg hydroxide

  • Stephanara

    Member
    March 16, 2022 at 12:50 pm

    PhilGeis said:

    btw - NaOH and Mg sulfate will likely precipitate some Mg hydroxide

  • Stephanara

    Member
    March 16, 2022 at 1:02 pm

    PhilGeis said:

    btw - NaOH and Mg sulfate will likely precipitate some Mg hydroxide

    @PhilGeis, do you mean I shouldn’t expect  a stable product after neutralizing and adjustment with Mg sulfate. I have kept some samples on the fridge as suggested by @ketchito, although I have not been able to do the one of warming up

  • PhilGeis

    Member
    March 16, 2022 at 3:21 pm

    Mg hydroxide is pretty insoluble.

  • Chemist77

    Member
    March 17, 2022 at 5:05 pm

    As @Abdullah pointed out, way too much LABSA and SLES. Cut down to half and then do what has been suggested. Mg Sulfate might help in clarity but this happens where certain polymers are used to build viscosity. I don’t use polymers or Mg sulfate. For preservative, I stick with Aqucar IG 50. 

  • PhilGeis

    Member
    March 17, 2022 at 5:36 pm

    Aquacar IG50 - glutaraldehdye - is good chemically.  At alkaline pH , it’s a good biocide at alkaline pH but degrades rapidly.
    Not sure it has necessary EPA registration to be used in household product context so may not be legal for this in US.

  • Chemist77

    Member
    March 17, 2022 at 6:14 pm

    Aqucar GA 50 could be the alternative then, still not sure about USA though.

  • Stephanara

    Member
    March 19, 2022 at 8:39 am

    Kudos to everyone on this forum, especially those that have made great suggestions and comments on the topic being discussed. I took some time off because i ran into problem with.”bad” LABSA. Nevertheless, this is the third day I have kept the samples in the fridge, no precipitate observed yet with the two materials in question. I also subjected the samples to heat, no precipitate too. Does it mean am good to go? Also still checking out for a good , economical and compatible preservative. Thanks all.. Hoping to hear from you

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