Problem Analysis: The question asks for a method to prevent color bleeding or bleaching from cotton fabrics during the washing process.

Preventing Color Bleaching in Cotton

To prevent cotton fabrics from losing color during washing, Common Salt (Sodium Chloride, NaCl) is often used.

Mechanism of Action

• Common Salt (NaCl): Salt acts as an electrolyte. When added to the wash water, it helps the dye molecules to bind more effectively to the cotton fibers.
• It increases the ionic strength of the water, which reduces the solubility of the dye in the water and promotes its absorption and fixation onto the fabric. This makes the color more resistant to washing out.

Why Other Options Are Less Suitable

• Vinegar: While sometimes used in laundry for specific purposes, its acidic nature may not be universally effective for preventing color loss in cotton dyes and could potentially affect certain dye types.
• Sodium Carbonate: This is an alkaline substance (washing soda). Alkaline conditions can sometimes cause certain dyes to bleed or fade, and can also damage cotton fibers if used in high concentrations or for prolonged periods. It is not typically used to *prevent* color loss during washing.
• Lissapol: This is a type of detergent or wetting agent used for cleaning. Detergents are designed to remove stains and dirt, which involves dissolving substances, and would therefore be counterproductive for preventing color loss.

Conclusion

Using Common Salt during the washing of newly dyed or brightly colored cotton garments is an effective way to help set the dye and minimize color bleeding.