Acid Blue 90, also known as Acid Blue AS, is a synthetic acid dye typically used in the textile industry for dyeing and printing. Here are some of its basic properties:

1. Chemical Formula: Acid Blue 90 does not have a specific chemical formula as it is a mixture of different dyes. However, it usually consists of sulfonic acid groups, azo dyes, and various aromatic compounds.

2. Molecular Weight: The molecular weight of Acid Blue 90 varies depending on the specific dye composition within the mixture.

3. Color: Acid Blue 90 is a blue dye, and the shade can vary depending on the concentration and application process.

4. Solubility: Acid Blue 90 is highly soluble in water, which makes it suitable for dyeing and printing applications.

5. pH Sensitivity: As an acid dye, Acid Blue 90 is generally used in acidic pH conditions. It exhibits good color fastness and lightfastness properties when used within its recommended pH range.

6. Application: Acid Blue 90 is primarily used for dyeing protein fibers like wool, silk, and nylon, as well as synthetic fibers like acetate and polyester. It can also be used for dyeing leather and paper.

7. Fastness Properties: Acid Blue 90 generally demonstrates good to excellent color fastness properties, including lightfastness, wash fastness, and perspiration fastness.