Comparison of Lactic Acid Grades

Based on the product information, the three grades of Lactic Acid you inquired about have the following key differences:

• Lactic Acid (AHA) Neutralized: This grade has its pH adjusted to a higher level (pH 4.0-4.5 at 10% concentration). This significantly reduces irritation compared to the 90% grades, making it easier to incorporate into formulations without extensive pH adjustment. It still provides exfoliation and moisturization, maintaining an optimal exfoliation level while being less harsh.

• Lactic Acid (AHA) 90% (ordinary grade - smells): This is a 90% concentration of L(+) Lactic Acid. It has the characteristic sour smell. Its effectiveness in exfoliation and increasing ceramides is dependent on the final product's pH. For optimal efficacy, the formula pH should be between 2.5 and 4.0 (not lower than 3.5 for consumer products according to FDA guidelines). Using it at a higher pH (above 4.0) greatly reduces its effectiveness. This grade offers full potency but requires careful formulation to manage both efficacy and irritation.

• Lactic Acid (AHA) 90% Deodorized (odorless): Similar to the ordinary 90% grade, this is a 90% concentration of L(+) Lactic Acid. The main difference is that it has undergone a process to reduce its natural sour smell, resulting in a very mild odor. In terms of efficacy and pH requirements for optimal results and minimal irritation, it is the same as the ordinary 90% grade.

Conclusion:

The primary differences are indeed irritation potential (significantly lower in the Neutralized grade due to higher pH) and odor (present in ordinary 90%, reduced in deodorized 90%).

While the 90% grades (ordinary and deodorized) have the potential for stronger exfoliation results if formulated at their optimal low pH (2.5-4.0), they also carry a higher risk of irritation if not formulated correctly. The Neutralized grade offers a balance of reduced irritation and ease of use, providing effective exfoliation and moisturization without the need for significant pH adjustment in the final product, though its exfoliation power might be slightly less intense compared to the 90% grades used at their lowest effective pH.

Therefore, the results can be different depending on how the 90% grades are formulated. If budget is a concern, the ordinary 90% grade is typically the most cost-effective, but requires careful pH control in your formulation to achieve desired results and manage irritation. The deodorized version offers the same efficacy potential with less odor, at a potentially higher cost. The Neutralized version offers ease of use and reduced irritation, which can be beneficial but may come at a different cost and potentially a slightly different efficacy profile compared to a low-pH 90% formulation.