Washing clothes in vinegar, especially on the first wash, does not "set" the color in the traditional sense. Vinegar is commonly used as a laundry additive for several reasons, but its main effect on colored clothing is related to helping to preserve the color and prevent fading over time, rather than immediately setting the color during the first wash.
The acetic acid in vinegar can act as a mild natural fabric softener and has some other beneficial effects on laundry, including:
Color preservation: Vinegar can help lock in the colors of dyed fabrics and prevent them from bleeding or fading prematurely. This effect becomes more noticeable over multiple washes, rather than just the first one.
Removing detergent residue: Vinegar can help remove detergent residues from clothing, which can contribute to dulling or fading colors. By removing these residues, the colors may appear more vibrant after washing.
Softening fabrics: Vinegar can make fabrics feel softer and more comfortable to wear, which is particularly useful for items like underwear and bed linens.
Reducing odors: Vinegar has natural deodorizing properties, which can help neutralize odors that may be trapped in the fabric.
However, it's important to note that while vinegar can be beneficial for colored clothing, it is not a miracle fix for all color-related laundry issues. If your goal is to preserve the color and prevent fading, using cold water for washing, turning clothes inside out before washing, and using a gentle cycle can also help maintain the vibrancy of colored garments.
Additionally, some fabrics and dyes may react differently to vinegar, so it's always a good idea to do a patch test on an inconspicuous area of the garment before using vinegar in your laundry routine. If you're unsure about using vinegar or other laundry additives, it's best to follow the care instructions on the clothing label or seek advice from the manufacturer or a professional cleaner.