Throughout the long history of soap manufacturing, urea has been a frequent ingredient in the formula, and was highly favored by manufacturers. However, as time went by, urea's presence in soap products has become increasingly rare, gradually distancing itself from soap. The reasons behind this transformation are complex and involve various aspects such as economy, technology, and market.

I. The Past When Urea Was "Favored" in Soap

In the past, soap production relied heavily on urea. The primary reason for this was its excellent moisturizing properties. Urea is a natural moisturizing agent that can absorb moisture from the air and lock in the moisture of the skin, keeping the skin soft and moist after using the soap, greatly enhancing the user experience. Especially in dry climate areas, soaps containing urea can effectively alleviate problems such as dry skin and peeling. At the same time, urea is inexpensive and widely available, ensuring the moisturizing effect of the soap while significantly reducing production costs and increasing the profit margin of the enterprise. This is highly attractive to manufacturers who pursue economic benefits.

Furthermore, urea also has the ability to soften the keratin. It can dissolve keratin proteins and reduce the adhesion between the cells of the keratin layer, helping to remove the aged keratin layer on the skin surface, making the skin smoother and more delicate. This property not only enhances the cleaning power of the soap, but also endows the soap with certain skin care functions. Moreover, when urea is added to the soap, it can improve the appearance and texture of the soap, making the soap texture more uniform and the color brighter, thus making it more competitive in the market.

II. The Current Situation of the "Gradual Separation" Between Urea and Soap

Nowadays, the application of urea in soap formulas has significantly decreased, and the risk of allergies is one of the important factors. Some people have allergic reactions to urea. After using soap containing urea, their skin may experience symptoms such as redness, itching, and rashes. With the improvement of consumers' health awareness, the requirements for the safety of skin care and cleaning products have become increasingly strict. To avoid triggering consumers' complaints of allergies, many manufacturers have chosen to abandon the use of urea. 

Meanwhile, with the advancement of technology, numerous new moisturizers have emerged. For instance, glycerin, as a classic moisturizing ingredient, has excellent moisturizing effects and high safety, and is widely used in various skin care and cleaning products; hyaluronic acid, which can absorb hundreds of times its own weight in water, has outstanding moisturizing effects; and synthetic moisturizers such as propylene glycol, have stable performance and prominent moisturizing effects. These new moisturizers outperform urea in multiple aspects and have gradually become the new favorite of soap manufacturers. 

The innovation in production processes has also provided soap manufacturers with more options. Modern production technologies can enhance the moisturizing and cleaning properties of soap by optimizing the formula and improving the production process, without relying on urea. For instance, by adding natural vegetable oils, extracts, etc., it not only strengthens the moisturizing effect of the soap but also meets consumers' demands for natural and gentle products. 

The changes in market demand cannot be ignored either. Currently, consumers' demand for soap is trending towards diversification and personalization, with a greater focus on whether the products are natural, organic, and environmentally friendly. "Natural ingredients" and "no additives" have become selling points for the products, while urea, as a chemically synthesized substance, contradicts consumer preferences. To meet the market demands, manufacturers have adjusted their formulas, reducing or eliminating the use of urea. 

Urea, which was a common ingredient in soap formulations, has become less frequent. This is the result of a combination of factors such as technological innovation, changes in market demand, and enhanced consumer health awareness. This shift not only reflects the development and progress of the soap manufacturing industry but also demonstrates the strong guiding role of consumer demands on product research and development. In the future, as technology advances and consumer demands evolve, soap formulations will continue to undergo innovation, providing people with more high-quality products.