How does exfoliation from 40% Urea differ from hydroxy acid?

If you have a patch of rough/scaly skin, do both those products remedy that, and in the same way?

Comments

  • Urea and hydroxy acids affect the protein structures differently. Acids coagulates the proteins, so the process of exfoliation is slower (If you use the recommended % of an acid or an acid mixture). 
    You don't need to use 40% Urea solution to exfoliate the callused skin. 25-30% will suffice to remove it quickly and safely. 
    Another option is 3.5-5% KOH solutions, which are also known as " cuticle and callus removers" , manufactured in a form of gels and used in the salon industry and by foot care specialists. If you use the KOH as exfoliating remedy, it is highly recommended to apply efficient moisturizer to recover the skin barriers, because alkaline preparations destroy the skin proteins as well as the skin lipids (cell membranes, etc). 
  • vitalys said:
    Urea and hydroxy acids affect the protein structures differently. Acids coagulates the proteins, so the process of exfoliation is slower (If you use the recommended % of an acid or an acid mixture). 
    You don't need to use 40% Urea solution to exfoliate the callused skin. 25-30% will suffice to remove it quickly and safely. 
    Another option is 3.5-5% KOH solutions, which are also known as " cuticle and callus removers" , manufactured in a form of gels and used in the salon industry and by foot care specialists. If you use the KOH as exfoliating remedy, it is highly recommended to apply efficient moisturizer to recover the skin barriers, because alkaline preparations destroy the skin proteins as well as the skin lipids (cell membranes, etc). 
    If you used 10% urea on your face...what percentage of salicylic acid would have the same effect? 

  • @DaveStone 10% Urea is too much here. Usually, 10% Urea is used for "thick" skin type (palms and soles). Of course, it depends on the purpose of your formulation, but I would employ 3-5% of Urea. 
    The concentration of Salicylic acid also depends on the purpose of the formulation. Usually 0,5 - 2%. The higher concentrations bring your product into OTC category (For example, the preparations against acne) 
  • vitalys said:
    @DaveStone 10% Urea is too much here. Usually, 10% Urea is used for "thick" skin type (palms and soles). Of course, it depends on the purpose of your formulation, but I would employ 3-5% of Urea. 
    The concentration of Salicylic acid also depends on the purpose of the formulation. Usually 0,5 - 2%. The higher concentrations bring your product into OTC category (For example, the preparations against acne) 
    How fast does it take Urea to degrade?
    Say you made a solution of water, 5% urea, 3% niacinimide, and Germall Plus. Would it be okay if used within 1-2 weeks?

  • I don't see any obstacles with this combination if you utilize the mixture within a week. 
  • vitalys said:
    I don't see any obstacles with this combination if you utilize the mixture within a week. 
    Would you still need to include sodium lactate as a buffer? Is that always necessary?
  • The buffer is necessary if you want to extend Urea stability in the water solution. 
  • vitalys said:
    The buffer is necessary if you want to extend Urea stability in the water solution. 

    In the example formulation I provided, would 2% sodium lactate be enough?
  • Would adding a little citric acid (to lower PH) affect the urea?
  • It is very difficult (almost impossible) to tell how much you need to employ in your system - it all depends (water, urea purity, etc). You need to choose the buffing system, which would be able to maintain the pH at the particular level for a long period of time. Urea is most stable at pH 6-6.2, so you need to adjust the pH of your solution manually by adding components of the buffer literally drop by drop and then you will find out the % for your system precisely. 
    Another option is use esters of such acids as Citric, Lactic, etc. - Triethyl Citrate, Triacetin, Ethyl Lactate. They also effectively prevent the pH drift of urea solutions. 
  • DaveStoneDaveStone Member
    edited November 20
    vitalys said:
    It is very difficult (almost impossible) to tell how much you need to employ in your system - it all depends (water, urea purity, etc). You need to choose the buffing system, which would be able to maintain the pH at the particular level for a long period of time. Urea is most stable at pH 6-6.2, so you need to adjust the pH of your solution manually by adding components of the buffer literally drop by drop and then you will find out the % for your system precisely. 
    Another option is use esters of such acids as Citric, Lactic, etc. - Triethyl Citrate, Triacetin, Ethyl Lactate. They also effectively prevent the pH drift of urea solutions. 
    If using a buffer of citric acid and sodium citrate, what is the typical ratio?
    Would you just add the two ingredients until the desired PH is achieved? Or should they be premixed and then added?
  • I doubt the typical ratios exist. 
    Personally, I prefer to use a pure weak acid (e.g. Citric acid) and a pure strong base (e.g. 50% NaOH solution) to create a buffing system in situ and adjust pH to the required level in the system. 
  • @Pharma What's your take on this? You seem to be very knowledgeable of urea.
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