Better humectant: urea or sodium lactate

Which do you prefer?

Comments

  • They work in different ways.

    Why choose.

    I use them both in the same product.

  • They work in different ways.

    Why choose.

    I use them both in the same product.

    How do they work differently? Which is molecularly smaller?
  • chemicalmattchemicalmatt Member, Professional Chemist
    Not so sure about humectancy and those two, since urea is generally used as a keratolytic. Place a 40% urea solution on your nail plate and overnight the nail will have dissolved and you'll be ready for toe surgery.  Reason for using sodium lactate-lactic acid with high urea content is that is the best buffering system to stabilize urea at pH 5.0 - 5.5. Urea decomposes (reduces) into ammonia in aqueous solution - just ask any farmer who uses it for fertilizer.
  • DaveStoneDaveStone Member
    edited November 2021
    Not so sure about humectancy and those two, since urea is generally used as a keratolytic. Place a 40% urea solution on your nail plate and overnight the nail will have dissolved and you'll be ready for toe surgery.  Reason for using sodium lactate-lactic acid with high urea content is that is the best buffering system to stabilize urea at pH 5.0 - 5.5. Urea decomposes (reduces) into ammonia in aqueous solution - just ask any farmer who uses it for fertilizer.
    Urea can dissolve healthy nail too? Or just fungal-infected nail?
    Isn't sodium lactate keratolytic as well over 10%?
  • 40% Urea is one of the strongest keratolytics, as @chemicalmatt mentioned, but at the concentration of 5-7% it becomes one of the most powerful humectants ( I would say the best one). 
    @DaveStone Yes, 40% Urea will dissolve a healthy nail too.
  • I use sodium lactate on its own but I never use urea (in o/w) without sodium lactate (because buffer). As per my anecdotal experience nothing saves dry hands quicker than urea + sodium lactate.
  • PerryPerry Administrator, Professional Chemist
    @vitalys - better than glycerin? I doubt it
  • @Perry Actually, they are comparable in their effect, but still different. These two substances can apparently complement each other in different preparations. It also depends on a formulation and its purpose. However, there are plenty of formulations where Urea shows more pronounced and prolonged effect. For example, the special formulations for hand and foot care. I completely agree with @ngarayeva001 that urea is the best component to improve dry skin conditions. I can say the same about feet, atopic skin conditions, severe ichthyosis, hyperkeratosis, etc
Sign In or Register to comment.