Eosin 10 %, aqueous is a highly concentrated eosin solution that can be used both as a stock solution for the preparation of diluted working solutions and for direct application when very rapid and intense staining is required. Eosin is a synthetic dye from the xanthene dye group and has the property of selectively staining basic structures such as proteins. In histology and cytology, these structures are typically shown in pink or red.

The 10% aqueous eosin solution results in rapid and strong staining due to its high concentration. Compared to alcoholic eosin solutions, the aqueous solution has slower diffusion into the tissue, which may result in a longer staining time. However, there is less risk of overstaining with an aqueous solution because dye binding is kinetically controlled.

The use of a 10% aqueous eosin solution may be advantageous in special applications where particularly rapid or intense staining is required. However, it is important to monitor the staining carefully to achieve optimal results and minimize the risk of overstaining.

In addition, the 10% aqueous eosin solution can also be used with an addition of acetic acid to modify the staining properties of the dye and improve the staining of structures with weaker basicity. Acetic acid can improve the staining properties of eosin by partially protonating the dye, thereby facilitating dye binding to tissue.